I was taught that you should make your own blacks and dark colors with mixtures.  Donna, Kamloops

A:  If you have seen my paintings you know I like dark colors and you bet I use black!  For those of you who have read my article “light rules” or taken my workshops, you also know that I rarely mix colors.  For hundreds of years great painters, right up to the Impressionists, did their best to avoid mixing colors if they could use pure pigment colors instead.  Rather, they achieved their effects by applying pure colors directly on the canvas, either superimposed in transparent and translucent layers (glazes and scumbles, or veils) or by mixing them minimally directly on the canvas with the brush or palette knife.  All the secondary colors and beyond were done in this way.  They would make exceptions and mix together two or more colors in certain areas of the painting that they wanted, for aesthetic reasons, to look dull, or brownish and grayish.  Any mixture of browns and blues or whatever you like to approximate black will produce a dull, heavy color.  A pure pigment black like Carbon black will give a crisp intense black.  Mixing colors will never get the same clarity, transparency and definition you will get by using a pure black.  For shadows and transparent glazes, a black will have an incomparable effect.  The different blacks all have different properties as well.  The Mars Black and Carbon Black are more opaque, while the Bone or Ivory black are more transparent with less tinting strength as well.  The Mars black tends to be the warmest of the three.  So, of course, I have all of them in my palette.  Then again, I like black.

Q:  with your acrylic paintings do you mix the gel mediums with the paint for achieving the textured effects?  Linda, Vernon

A:  There is no technical reason why you cannot do that, but I rarely do, preferring instead to apply the gel mediums and texture before I start to paint.  Here again, the ’Light Rules’ apply.  I don’t like to add anything to the paint that will take away from the light or intensity of my colors, unless of course I have a reason for wanting a certain color to be dull or muted.  I start with the drawing on the white canvas or panel (‘Light Rule” no. 2) and then I put on the various mediums and textures to achieve the effect I want (I can still see the drawing underneath), I let it dry for at least a day, then I paint over top of the textured surface.

Thanks for the questions, David

Different glazing mediums for acrylics

Hi David,

I took your first Acrylic course and I will be taking your second course Mastering Acrylics II on April 12. I now understand your comments during the course that the indirect method of painting has a lot of potential, especially since I’ve seen Rembrandt’s work. It took me a year to finally figure out how I could use that method in my style of work. I use ¼ inch masonite (hardboard). I divide a sheet into standard sizes of 24×18, 20×16 and 11×14, priming both sides and edges. I started out producing a number of paintings using GAC 100, the only problem was trying not to create tiny air bubbles and I noticed that it levels out too much. So, after 25 paintings, I’ve decided to try GAC 200 to get a more built-up texture effect. I’ve done 3 paintings now and 2 of them showed signs of cracking (like the old varnish crackling effect) in just one or several spots, the size of a pea or bean. I’m not sure if it’s my technique or the product. I’m meticulous so I believe the following could have happened:
-During trowelling there was air or a drop of water.
-Board was bumpy•
-Flex in the board.
-Contamination of the product.
-Painting may not be dry enough.
I did allow the painting to dry for 24 hours before the application. I’m unable to figure out why 2 out of the 3 paintings cracked. As I have a showing slated for West Vancouver and Whistler, I’m planning on using GAC 100 again. However, if you have any suggestions I would appreciate it.

Thanks, Kurt

Hi Kurt,

Lets see if I got this straight: you used GAC 100 for glazing and you got bubbles, then you tried 200 and got cracks. Am I right? Bubbles are almost always caused by too much water in the mixture. Make sure your brush is dry!!! Also, foaming can occur if you are scrubbing with a thick amount of glaze medium over a textured surface, again, more likely if there is water in the mix. GAC 200 is not formulated to be used as a glaze medium and is the hardest (and therefore most brittle) of the GAC series. It is more for sizing/priming smooth surfaces because it is very sticky, like glue. It would be the most likely to crack.

Along with their regular polymer medium, which is fine for glazing, Golden has produced a number of special purpose acrylic polymers, called the GAC series. There are five of them: 100, 200, 400, 500, and, 700. Each is specifically formulated to have different properties that are useful in different applications. For example, they can regulate the paint to make it more transparent, or change the viscosity, adhesion, flow characteristics, and so on. Golden has information pamphlets that you can get at the art supply store, or you can go to their web site, to find out more about the specific properties of their mediums and their recommended applications. GAC 100 and 700 are the best for glazing (i prefer 700). Also, using a glaze to create build-up or textured effects is not effective. Not matter how much you use they will all level out. For texture and thick applications you must use a lot of thick paint from the tubes or use the various gel mediums. If there are other concerns that I have not addressed here Kurt I will need more specific information about your methods and the materials you are using…you can let me know. Hope that helps. See you in April Kurt. David

Tips for Glazing in Acrylics

Hello, I was reading on the website about glazing etc. and I was wondering if you could direct me to more information about indirect painting. Currently I am considering buying some more glaze-appropriate paints and don’t want to waste on unimportant colors etc. Also, I have read some various techniques and am unsure about which ones “do” which. For example I read that Leonardo worked from a dark underpainting whereas Rubens went from light to dark. I don’t know what is appropriate for me.  I think that I will pursue this method of painting more than many others so I am trying to get a good introduction and background. Thanks for any help you can offer.  Ari

Hi Ari,

That is true, da Vinci and Ruebens had very different approaches, and mediums, for painting in oils.

You can glaze with just about any color in oils or acrylics.  The transparent colors make more transparent passages of course.  Most Manufacturers have charts or symbols on the tubes that identify the relative transparency of the pigments.  It helps to know that it is the pigment itself that imparts the specific transparency/opacity to colors and not the medium as much.  So, a transparent/opaque color will have the same properties in oils, acrylics, and water-media paints.  Remember too, that there are many, many more colors available to us modern painters than at any time in the past.  A good, glossy medium to mix with the paint is the key however.

Hi David,

I am an amateur painter, using acrylics paints, which I love.  I have been working hard to figure out and understand how to effectively use acrylic mediums to create deep glazes.  Then I came across your paintings and saw, frankly, that you have achieved what I have been trying to capture – your paintings are
Fabulous!!!!  I am keenly interested in learning more about
Glazing, and understanding your method.

What medium(s) do you use?  How do you “build’ the paintings from the start?  This may be presumptuous of me to ask for this information and expect to just receive it.  Let me know what you think about this idea!
Thanks, Brian

Hi Brian,

I am happy to share any information that might help you on your quest.  I remember doing the same thing, the only problem I had was that all the painters I wanted to learn from had been dead for a few centuries.

You would enjoy taking one of my workshops called ‘Mastering Acrylics.’ The FCA has one scheduled in Vancouver for September 27-28.  The Federation has many great artists among the members and most are happy to share their knowledge and skill with other painters.

In the meantime, start by reading and studying this article:  (insert link to ‘light Rules’ article on FCA website).  It is a collection of guidelines for painting that I learned by studying the methods of the greatest painters since the Renaissance.  In my opinion it is the essential foundation for superb technique and it applies to most mediums, including acrylics.  It is the basis of my teaching and the subject of a book that I will one day get around to publishing…

For now, here are a few tips to get you started.  I have come to prefer the Golden GAC 700 medium for glazing, it is less sticky and flows better than regular gloss medium, and; I never use matte medium, and little, or no water in my glazes and veils (a glaze with white or another light opaque colour added) – and I keep my paint brush clean and dry, that is, no water in my brush.  This insures that the glazes and veils remain luminous and transparent.

I use gel mediums of all varieties to create textured effects.  I rarely mix them with my paint, preferring to apply them first.  Once they are dry I paint in layers over top of them.  From a technical standpoint it is perfectly safe to mix them with your colors, but again, I do not like to add anything to my paint that compromises its transparency and color saturation.

Thanks for the question, David


Hi David,

I just came from your advice on webpage
http://www.artists.ca/FCA-7cd.html and wanted to thank you. It’s difficult to find someone who can give advice beneficial to beginners that is palpable. I have been contemplating seasoning my canvaseswith a color then painting over it until I saw your advice Rule no. 7 says only paint under an object with a colour that you want to have under it. Simple, easy and makes perfect sense.

I also have a tech question and can’t find an answer.
I’m trying to find a middle gray, oil paint and cannot find any. Is there any such thing as an 18%-gray, oil paint?

Thanks again, Joel

Hi Joel,

I have never heard the term ‘seasoning’ with regards to artist’s paintings but
starting a painting on a colored surface is a common practice that painters have been using for centuries. the way it works is you apply a transparent layer of color over the white primed canvas. often artists apply this over the intial drawing to seal it as well. this colored layer, called an ‘imprimatura’, would serve to provide a medium toned surface on which the forms and colors of the subject could then be developed. it also serves to add an overall harmony to the composition as the initial color can be seen showing thru the layers in varying degrees throughout the picture. Rubens mostly used gray tones for his imprimatura, Rembrandt, brown or gray, the great venetian artists like Correggio and Titian liked to use red earth (iron oxide red).

I am not sure what you mean by ‘middle gray.’ Are you
talking about a neutral optical gray like a photographer uses? the most
common gray found in artists paints is called ‘paynes gray’ and it is quite dark. as a rule painters mix their own grays using colors from the palette they used in the painting so that they will better blend into the color scheme. a brown and blue that were already used in the painting mixed with white for example. hope this helps, david

I would like to describe, and for those who have taken my workshops, review the idea of ‘indirect’ painting that comes up so often in questions to me about my painting techniques.  So here is a short story about the ‘indirect’ way to paint:

Like many artists, I started painting before I had any formal training in art.  So, like most people who have a desire to paint in a representational way, I just started mixing and matching colors as I saw them in the photo or subject I was trying to represent.  For example, if I was painting a blue jacket I would mix up some blue and white and perhaps add some red if it was a warmish blue and then I would add some black or purple or green or all of the above for the shadows, lighten it with white for the highlights, and so on.  Then I would proceed to mix and blend them all together to create the curves and folds of the fabric with all the shadows and highlights.  It was a tedious task that required patience and a good eye.  Not to mention small brushes and most certainly oil paints because acrylics do not work well in this method as they dry too fast and are too sticky for all that blending that goes on.  Painting in this way I was able to create very realistic, photographic like representations of subjects.  I have come to categorize this method as the ‘Coloring’ or ‘Illustration’ style of painting and it has been exploited to great advantage by some photo-realism and wildlife artists in recent decades.  It is interesting to note too that this style of painting is new to the 20th century; well-known artists in centuries past did not paint in this manner as a rule.

When I started my fine arts courses in college and university that method of painting was discouraged in favor of the more spontaneous approach made famous by the Impressionists.  This ‘Direct’ or Alla Prima style dictates that we think boldly in terms of simplified forms and color areas and apply the paint with a minimum of blending.  With this method you could paint in a representational way but the image would look more  ‘painterly’ or ‘impressionistic.’ To paint effectively in the Direct method you still need a good eye but instead of patience you had to be clever at synthesizing and simplifying color schemes and forms in a bold and decisive manner.  Are you still with me?

By the time I was a short ways into my university painting courses I had absorbed and understood these two ways of using paints to make a picture.  Then, rather than dose off in my art history classes when the professor turned off the lights to show us slides, I started to notice the painting techniques of some of the painters of previous centuries.  When I saw paintings by artists like Raphael, Titian, Rembrandt, and Rubens I noticed that although they were painted in a very realistic manner, their paintings were not at all stiff and labored like most paintings done by ‘coloring’.  I could see that these artists did not spend hours blending with fine brushes but, like the Impressionists, used bold and direct methods to apply their paints.  In fact Rubens was know to have finished an entire large canvas in one sitting.  The images were dynamic and painterly and with an inner life and depth that amazed me.  This is something that I had never seen in any modern painter’s work. There was nothing that I had learned on my own or in the university painting classes or had seen in ‘how to’ books on painting that could explain how these artists achieved the effects that they did.  I quickly discovered that neither the art history teachers nor the painting instructors had any answers either.   So I got a university degree in fine arts and still didn’t know how to paint to my satisfaction.  As a painter I wanted to know that I had the skill and knowledge to create any effect that I could imagine, or see in another artist’s work, be they contemporary or from as far back as the early Renaissance.

I had come across the ‘Indirect’ method of painting.  To learn the secrets of the Old Master’s techniques, though, I had to do some serious research.  It was only through years of studying old manuscripts and out of print publications on artist’s materials and techniques that I was able to rediscover for myself  the art of indirectpainting.  I spent years studying and painting in the style of my favorite painters of the past like Rembrandt, Carravaggio, Titian, and Rubens.  These were my true painting instructors.  Later I adopted acrylic paints and found that they were, in many ways, well suited to this ‘new’ style.

In this indirect method of painting the artist would paint in successive layers of transparent and translucent colors (called ‘glazes’ and ‘scumbles’ or ‘veils’) to achieve their effects.  Like with the direct method there was still very little blending of colors; but rather than being applied in opaque layers side by side they are applied one on top of the other so the layers of paint underneath were allowed to show through.  In the case of the blue jacket described above, an artist like Titian would probably have first painted the jacket with all the shadows and highlights but only using gray and so that it looked something like a black and white photo, this is called a ‘Grisaille.’ When that portion was dry he would then apply a blue glaze over the entire area to give it the color.

What I noticed in studying the paintings of the so-called Old Masters was that you invariably find a mixture of all three painting methods in a single painting.  In different parts of the painting you would find areas of transparent layers (indirect), bold patches of thick pure tones juxtaposed (direct) and occasionally duller areas where the artist blended colors to create a certain effect (coloring).  When I teach painting I focus almost exclusively on theindirect method because I know that these days the other two styles are easily learned.  The way I look at it, theindirect techniques simply give the painter a few more tools to help expand their expressive possibilities.

If you want to get the whole story on how the old painters achieved their remarkable effects and how this knowledge came to be lost over the centuries, you can come out to my lecture/slide show on Thursday November 15 entitled:  The History of Oil Painting Technique”


You seem to be an expert in glazing… And as an aficionado of similar painters, I was wondering if you could give me any suggestions of specific colors that I might glaze for flesh tones (Caucasian)….warm and cool… I am familiar with the glazing process, but am now just getting into portraits and I don’t know where to start. Any suggestions???


Hi Camille,

Good question. I will assume that you are painting in oils. Doing portraits in acrylics using glazing techniques would be… umm… tough. There are several ways to go about this. I will give you a few takes on it and you can come up with a combination that suits you. The basic colors for skin tones are:

-burnt umber and/or raw umber
-burnt sienna
-yellow ochre and/or transparent yellow ochre (oxide)
-vermillion (cadmium red light)
-alizarin crimson used to be the transparent red for figures, it has now been replaced with the more lightfast quinacridone reds.

You first have to decide how you want the underpainting to look. When studying the portrait painting techniques of the Old Masters from the Renaissance to the end of the 19th century, the ‘golden age’ of oil painting IMHO, you will notice that the most common approach for the underpainting is to do a simple “grisaille” using black and white. Some of the earlier painters also liked to add cooler colors, green or blue perhaps, to the grisaille to counteract the inevitable yellowing of the oil paint with age. DaVinci fancied a purple hue for his grisaille as he figured that the yellowish skin tone would be best offset by its complimentary. Regardless of which method you use the essential factor is to keep this underpainting light because subsequent layers (glazes) will darken the image. A rule of thumb is to make the underpainting 1/2 as dark as you think you want the final painting to be. Once the underpainting is dry you can start adding the layers of color. You can go about this in several ways.

You can choose to glaze the whole area with the burnt
sienna and blend a mixture of white and ochre into that wet glaze. Or just reverse that order and glaze the yellow first, especially if you have a transparent yellow oxide instead of the opaque yellow ochre. Later, you can blend in the red (vermillion) accents.

Alternatively, you can mix a semi-opaque veil of flesh tone by adding a transparent medium to a yellow ochre, vermillion and white mixture. Paint this over the entire area and commence blending the vermillion and white accents into it.

Most painters would leave the shadows and highlights to the end. The shadows can be glazed over the dry skin tones or blended into them wet, as you prefer. The browns, black, blue, purple, and greens can all be used in various combinations to create glorious shadows and dark areas. Don’t forget the important neutral gray tones that can be achieved by blending your dark colors with the light tones. These grays are usually painted into the transition areas between light and shadows.

Another approach would be to put down a brown glaze to start then mix the grays into it and then blend the flesh colors while the whole underpainting is still wet. Later you can return to this dry preparation to add more glazes and opaque accents. A favourite method of painters like Rembrandt was to start every sitting by putting a glaze (usually brown in Rembrandt’s case) over the whole painting and then blend opaque colors into the wet glaze.

I could go on but I trust you get the idea. Perhaps the best method of learning is to watch a good portrait painter in action. David Goatly (SFCA) of Victoria does fabulous portrait work.

Hope that helps to get you started anyway… Have fun, David


What a thoughtful and insightful response! (I wasn’t even sure if you would get back to me.) You blew me away with your expertise and knowledge! So few people out there know this stuff — today is my lucky day!! :). This information is bound to help other artists out there. THANK YOU!!! THANKYOU!!


I have a couple of questions here from Karen and Pat about Greens.  Painters and paint manufacturers have been trying for centuries to put together a natural looking, pure pigment green paint color, and with limited success.  Read on…

Q:  I have a question that has to do with the permanency or non-permanency of Chromium Oxide Green (isTerre Verte the same thing?)  It’s the only pigment on my palette about which I am uncertain.

A:  Professional grade chromium oxide green is rated as very permanent.  It is a stable color in all types of paints.  Terre Verte or “Green Earth” is not the same pigment, but that needs to be qualified.  Terre Verte is a natural clay colored by iron and manganese and was a very popular color during the Renaissance.  It has low tinting strength and is transparent and has limited use in oils, except for glazes.  Nowadays, it is rarely used to make colors as the best clays are hard to come by and expensive.  When it is used for oils it is often strengthened with oxide of chromium, hence the confusion.

Q:  I really love the Sap Green that you use.  You said it was Windsor & Newton.  I am assuming that it’s from the Finity series, which I noted on the internet.  It is the only one I can find in Windsor & Newton.  The only greens I have are Chromium Oxide and Pthalo Green and I don’t really like either one of them for the piece I am doing right now.  I realize that I can mix the paint to get sort of the right color, but your advice is to keep the colors pure.  Can you please let me know if it is Finity or not?

A:  Yes it is.  And it is one of the only colors in my palette that is not a pure pigment color.  It is two pigments co-precipitated to make a single hue – as close as you can get to a pure pigment color as far as I can tell.  To my knowledge, Winsor & Newton is the only company that makes this color.  It is an excellent, natural looking, transparent color – great for landscape painting.  Chromium Oxide and Pthalo Green have limited use in for landscape painters.  Still, I most often prefer to make my greens by using combinations of blues, pure greens, blacks, yellows, browns, and oranges, glazed over one another in various combinations to make an exciting array of greens in my landscape pieces.  This way the colors have all the depth and intrigue but still remain separate, pure.  Try it out.  Mix a blue and a yellow to make a green.  Then, take the same blue and paint it on thinly over the white canvas, so it is transparent.  Then, mix your yellow with some glazing medium and paint it over the dried (this is vital) blue.  The resulting green will be far more interesting and lively than the mixture.

I was asked this question recently at a workshop.  Watercolor painters do ‘washes’;oil and acrylic painters do ‘glazing’ to achieve a similar effect.  Still, many artists do washes with their oils and acrylics by diluting them with either solvents (oils) or water (acrylics).  I have noticed this is especially true of watercolor painters.  They also have a habit of working with a wet brush, this also has the effect of over-diluting the paint.  These oil and acrylic washes may look all right but from a permanence point of view they are not a good idea.  Here is the difference…

Oils and acrylics are what are called “body” paints, they are thick and viscous and the pigment particles are surrounded by the oil or resin (binder).  This protects the pigment and insures that the colors remain vibrant and transparent.  The binder also keeps the paint film strong and flexible.  If you dilute the paint with too much thinner you wash away much of the binder and the pigment is left exposed and unprotected.  This is the main reason why watercolor paintings need to be framed behind glass.  You could not varnish or clean a watercolor painting without disturbing the unprotected color.

When oils and acrylics are used for watercolor-like washes the paint film and colors will look matte or dull because there is less of the binder to reflect light.  Remember too that the ratio of binder to pigment is much higher in watercolor paints so the colors are more intense when diluted for washes.  A wash done with oils or acrylics will also be more absorbent than normal so it will soak up binder from any layer of paint put over it leaving that new layer dull and matte as well.  These ‘lean’ layers of paint will be brittle and will easily crack, especially with oil paints on canvas.  If you were to varnish a thin wash of acrylic or oil paints the varnish would be absorbed into the paint layer rather than sitting on top of it where it could be easily cleaned or removed.   For permanent results, any oil or acrylic paints used in this way should also be framed behind glass, like a watercolor painting.

Glazing is a good alternative when using body paints.  A glaze is like a wash because the color is diluted, but not the binder!  Instead, the binder is replaced by a transparent glaze medium.  The glazing medium when mixed with the paint ensures that the colors remain transparent, giving life to the underpainting, while still protecting the pigment and the integrity of the film.  For oils and acrylics you should only use enough solvent or water to thin the paint enough to help it spread a little easier, up to a maximum of 25%.  A glaze is made by adding a medium to the color and a small amount of solvent or water when needed.

For washes, the best results from a permanence perspective are achieved with watercolors and Egg Tempera paints.  For oil and acrylic paints learn how to create lustrous transparent glazes over dried, light areas of the underpainting –  and keep your brush dry!

Brushes n’ Things

Brushes aren’t as important for acrylic painters as they are for oil painters and certainly not watercolor painters.  Acrylic paints are hard on brushes.  An oil painter can have a favorite brush for years if it is well taken care of.  When painting in acrylics you have to constantly wash the brush and scrub the paint out of it before it has time to dry.  Even then, a small amount will stick to the hairs and eventually the brush will lose its shape.  Good brushes don’t make much difference for acrylics like they do for oils and watercolors, so inexpensive synthetic hair brushes serve well for most purposes.  Oil paint is thicker and more dense, different brushes and brush-work will affect the look of the paint and it will hold its shape.  Acrylics are lighter so you don’t usually need a stiff bristle brush to push them around.  When the acrylic paint dries it shrinks and levels out so the textured brush-work is mostly lost.  There are mediums that will give the paint a stiffer texture however.  If you take good care of your nylon hair acrylic brushes they will last a reasonably long time and then you simply replace them.


I use nylon brushes for acrylics almost exclusively and especially the chisel tip variety.  With those you can paint a larger flat area, you can turn the brush on its side and paint a thinner line or you can tilt it and use the point for fine detail work.  I use natural fiber oil painting brushes for fine detail work.


Brush Maintenance


An oil painter will often have two or more brushes going at the same time, one for each color.  With acrylics, you could never paint fast enough with one brush before the others dried out.  Acrylic painters will use one brush at a time and wash it regularly.  That’s why I love those multi-purpose chisel-tip shaped brushes; I can do most of the painting using only one brush.  When you are done using a color you must wash the brush and dry it thoroughly before you use the next one.  If you have more than one brush going, one must be left in water.  You will need some good dry rags on hand while you paint.  If the brush is in the water for more than a couple of minutes it should be scrubbed to remove the paint from it because the paint on the inside of the brush will continue to dry even in the water.   For this reason it is important to have a screen of some sort in your water container to scrub the brush on and to prevent the brush from resting on the bottom where all the pigment settles.  When you are finished painting the brushes can be rinsed in warm water then washed with a mild soap.  They can be stored lying flat or standing with bristles up.


Painting and Palette Knives


There are two types of knives designed for painters:  one is the painting knife that comes in a variety of shapes and the other is a palette knife used for mixing paint on the palette.  The painting knives have a bent handle so that they can be held horizontally to the painting surface without you getting your fingers in the paint.   The palette knives have a straight handle.  I like to use painting knives for mixing on the palette and for painting because I like the bent handles.





There are a variety of materials you can use for a palette:  wood, glass, wax paper, and so on.  For acrylics, glass works well because it is easy to clean.  Just soak the dried paint in water for 15 minutes and it will peal right off.   Many painters also like to use the ‘wet’ palettes that are come with lids to keep acrylic colors workable between sittings.


Humidity & Cleaning an Oil Painting

Hi David,

My gallery called today asking me a technical question.  I answered the best I could but I felt it deserved your expertise.  The Gallery is adding on a storage room on the outside frame of the building.  It will be insulated but not heated. They were concerned with humidity, condensation, and dampness (maybe these are all the same thing).  The problem should be minimal as they are doing everything to create a completely dry space there.  How do paintings stand up to the possibility of these problems?  The paintings are mainly acrylic on canvas.  My concern was that the gesso or canvas could become moldy.  I wasn’t sure about the acrylic paint itself.  I would really appreciate your opinion so that I can pass on an informed answer.

Thanks so much David, Donna


Hi Donna,

Your observations are correct.  Humidity can be a problem for paintings.  Paintings prefer a dry environment that has a constant temperature – this is the most important factor.  An unheated area can have large fluctuations in temperature and that causes condensation (humidity that turns to water forming on surfaces when cool and warm air get together) and this is a how mold and mildew can become a issue.  It is not usually the painted surface that is attacked but rather the supports – canvas, paper, and wood.

Temperature fluctuations can also be a concern for acrylic paintings because they are thermoplastic.  That is, they are hard when cold and sticky and soft when hot.  They must take care that the acrylic paintings are not touching any surfaces (esp. other acrylic paintings) that they will adhere to.

They might consider a space heater for the area and even a dehumidifier.

Best wishes, David


Hi David,

I would like to know the process of cleaning an oil painting and if any touch-ups would be required to the painting itself after a cleaning?


Hi Donna,

If the painting is dirty or has a difficult build up, use some mineral spirits.  Dampen a soft, smooth, lint-free cloth with it and rub gently one small area at a time, perhaps 2 square inches.  Do not put too much so as to wet the paint excessively as it can seep through and loosen the paint from underneath.  If the painting is on canvas it helps to have a support under the area you are cleaning so that you are not applying too much pressure to the canvas.

Hopefully the painting has been varnished in which case you will not be cleaning the paint itself, but just the varnish.  The painting should need any touch ups.  Never use water to clean an oil painting.



Texture With Acrylic Mediums

Hi David,

I noticed that your acrylic paintings are built up with lots of  texture and thick applications of paint. What particular medium do  you prefer for this technique? Heavy gels, perhaps? Have you managed to find a way to get this thick acrylic paint to resemble the textures of oil paint and, specifically, the way oils can hold all the peaks and ridges and subtle details perfectly.

Thanks, Steve

Hey Steve,

Good question.  I use all kinds of texture mediums to create different effects.  When I first started using acrylics you could get gel medium and molding paste.  Now there are many to choose from, each with its own characteristic properties to impart a wide range of textured effects and techniques never before possible with oils.


The ones I use most often are the medium and heavy gels, the molding paste, pumice gel, and a few others here and there for various effects.  You have to try them all out to become familiar with how they will work for you.  Because all acrylic mediums are made with acrylic resin they are all intermixable and can be added to the paints in almost any proportion and combination.  The only precautions would be to make sure not to use the more stiff mediums, like the pumice and molding paste, in thick layers on a flexible support like canvas as they may crack.


With rare exceptions, I do not mix the mediums with the paints but rather apply them first and then paint over them when they are dry.  This method insures that the intensity and transparency of my colors remains unaffected, which is important to me in my work.


Compared to acrylics, oil paints are easier to work with under the brush, and you can create many more effects with a variety of brushes and techniques.  With oils, smooth blended effects and subtle nuances are readily achieved with different brushes and a skilful hand.  Acrylics dry much faster, so you need to decisive, put the paint down with a swish of two and leave it be, otherwise you will end up with ‘marring’ – streaks.  Acrylic paints are also much lighter than oils and so are easily pushed around with a soft brush.  Expensive brushes and fancy methods are all lost on acrylics though because when the paint dries they all but disappear.


To some degree you can get the acrylic paint to remain stiff and retain its brush marks and peaks by adding molding paste or even a very stiff gel medium, but it will never be as good as oil paints in this regard.  The reason acrylics don’t behave as oils do in this way is because they shrink and level out somewhat after the water, which takes up considerable volume in the paint, evaporates.


By adding a medium like molding paste you can make it stiffer and it will shrink less but then the molding paste dries white and will effectively lighten, dull down, and rob the colors of their transparency.  Oil paint has a higher pigment to medium ratio than acrylics and so the colors tend to be brighter and more intense.  Plus, of course, by taking up a lot of the volume of the acrylic paint with mediums, you are dulling them down even more.  If these things are not an issue in your composition, then it is worth a try.

The Art of Subracting Light

I just taught another workshop and one of the issues that I always cover, and that invariably creates misunderstanding, is the notion of painting over a dark underpainting.  Let me explain.

I am often asked how I am able to achieve the luminosity in my paintings.  In fact, when I ask, it is perhaps the most frequent reason given for taking my workshops.  This, in spite of the fact that I like dark compositions and am fond of using the nemesis of modern painting styles; black paint.  My painting style, and my teaching, is based on the methods of the painters of the Renaissance who were very insistent on painting on a smooth white ground, and on keeping their underpaintings light.  This is contrary to how many contemporary painters develop their compositions, i.e., from dark to light instead.  In fact, many artists now use gray or black gesso, or start their paintings with dark hues and then paint over them with bright opaque colors, adding light as they go so to speak.  Remember those Elvis paintings on black velvet from the 70’s?  This can be an effective technique for creating compelling compositions if done well, but it is contrary to everything I teach about how to create luminous paintings that reflect the maximum amount of light, and color intensity – I advocate subtracting light instead.


There are several methods that I adhere to that keep my paintings luminous and my colors intense:  I use only the best quality single pigment paints, and I do not mix colors (like red and yellow together to make orange for example); for transparent effects I use only gloss medium to mix with my paint, and lots of it, never matte medium or water (nor solvent for oils).  Perhaps most significant however, is the centuries old practice of reserving the darkest passages for last, and then, mostly in transparent glazes.


When light hits the surface of a painting it will pass through all but the very thickest and most opaque layers and reflect back whatever is underneath.  If the surface underneath is smooth and white, then pure light is reflected back and that literally illuminates the layers on top of it and makes the colors ‘pop’.  You can imagine then that conversely, if your ground or underpainting is dark, it will absorb most of that light and those dark hues will be reflected back and extract more light and intensity from the colors that are on top of it.  You can test this for yourself with a simple exercise:  create a composition using bright colors over a dark underpainting, say dark brown or black.  Then do the identical painting, except on a smooth white surface instead.  Compare them side by side.


The issue is all the more pertinent if you paint in oils because oil paint becomes more transparent with age.  Therefore, if your oil painting has a dark passage underneath a light opaque area, it will look very different decades later as the paint gets increasingly transparent and the dark hues show through even more.  This is the reason that the early Renaissance artists painted their light hues very thin over light underpaintings, and their dark colors heavy and opaque.  Again, the reverse of most contemporary artists who tend to paint the light opaques thick, and the darks thin.  This is also the main reason why so many great oil paintings done after that time have turned much darker than the artist had originally intended – they were not aware of how important it is to keep the ground and the underpainting light.  The paintings of the Renaissance Masters are a testament to their technical expertise – the colors are still vibrant and bright centuries later.


I can’t remember if it is my own quote or where I may have read it so I am going to take credit for it until someone corrects me:  “The art of painting is the art of subtracting light.”  The crux of the matter is that it is easy to subtract light from your composition (by adding layers of paint), but once it is gone, it is very difficult to get it back without the painting looking overworked.  If you want to maintain the luminosity in your work and keep the colors intense, start your painting on a bright white surface and subtract the light gradually by working from light to darker until you have subtracted just enough light, but not too much.  That is when the painting is done.

Tips for Oil Painters

Hi David,

I read your article in the Art Ave. Thanks for supporting artists.  I have been painting on canvas with oils and I do the following:

-stiffener on the back (Gac 400)

 -isolating layer on front (Gac 100)

– acrylic gloss medium on top (for porosity and enough smoothness for me to do my new techniques)

– oils on top of that.

It seems to work fine. I use alkyd medium (Liquin) which equalizes the drying time of all the paints and leaves a soft pliable film when dry.  If I need more open time with the paint, I will add a few drops of refined linseed & poppy oil. The refined linseed is much cleaner than what was used in the Renaissance period. The poppy oil is even slower  drying but keeps the tone light. Monet used poppy oil in his Plein Aire paintings and they stay very light, even well after a 100 years of age. However, on its own, it doesn’t have the adhesion intensity of linseed.  If I need to thin the paint a little more, I use Gamsol, which has a very low OMS rating.

The real problem for me is not while I am painting….its the off-gassing of the oils 2-3 days later, and for many months.
Have you found any information on off-gassing of acrylics, particularly the slow-drying ones? I know the older acrylics used formaldehyde and ammonia, which I can’t stand…makes me cough!
Any comments or suggestions on the above info?

Cheers, Marion

Hi Marion,
You have a much better understanding of technical issues than most artists for sure.  The way that you are preparing your canvases for oils is exactly the way I recommend except for the last layer of gloss medium.  Gesso is the ground and it is essential as it provides some absorbency and ‘tooth’ for the oil to adhere better to.  Oils and acrylics don’t adhere well to each other at the best of times, a glossy medium on a flexible fabric will not create a lasting bond.  The centuries old method of putting down an Imprimatura over the gesso, that is, a tinted varnish or glaze (an alkyd medium tinted with any transparent pigment and diluted with a bit of solvent works great) to make it smoother and less absorbent, works perfectly.


Poppy seed oil is slower drying than linseed oil, and yes it does not yellow and darken with age as much.  The drawback with it, as you say, is that it is has less flexibility and adhesive strength.  Walnut oil was commonly used in painting during the Renaissance and earlier as it combined the best qualities of all the drying oils and was favored by painters like Da Vinci who preferred a slower drying time.  M. Graham makes their oil paints using walnut oil.  Da Vinci would also add Spike oil to his paints to further slow the drying time.  Adding additional oil to the paint, which is a common practice in recent times, is not a good idea.

Modern oil paints are all made using straight oil and pigment (Schmincke paints are the only exception that I am aware of), and that is already too much oil.  The early oil painters made their oil paints using a mixture of oils and resins to help off-set the drawbacks of pure oil in the paint.  It may seem like blasphemy to some but I would not take technical advice from the Impressionists.  Artists were already ‘in the dark’ when it comes to technical expertise by that time, and in spite of their brilliant compositions, their paintings have not aged well and have darkened considerably since they were created over 100 years ago.


For more information and tips see my article entitled “Oils vs Acrylics” in the Sept/Oct 2012 issue of the magazine and go to the technical Q&A page on my website.

Acrylics do use preservatives and anti-fungal agents like ammonia in the paint but I don’t know exactly which ones are being used these days.  Better to ask the different paint manufacturers if you think it is a concern for you.  In general, off gassing of these elements is of little concern unless you are painting very large painted areas at a one time in a confined area with poor circulation.

All the best, D


I have been painting for about 3 years, not in well ventilated area. I do not buy really expensive paints (2 to5$) I was wondering if they can still make me sick. I really get headachesand just don’t feel well when I am painting. My daughter brought itto my attention yesterday when I was showing her some work in my office and shesaid the smell was so strong. I would like you to let me know.

Thanks, Bonnie

Hi Bonnie,

Cheap paints can make you just as sick as expensive paints.  Probably more sosince there are more fillers and additives.  All types of paints give off vaporsfrom chemicals and volatile solvents, some types more than others. What type of paints are you using?  Oils, acrylics…   Some artists have exhaust fans installed in front of their work area or easel to pull out the vapors.  You can also use a fan in the window to do the same thing.   David, I use a mix of Neon(apple Barrel) Metallic (Anta’s) and of course theAcrylic’s of Academy and Liquitex (Basics). I work on canvas and work in a12x12 or so room. I know when I use the Neon it is really strong vapors. Iwill just have to start using a fan, or something. I thank you very much foranswering my question. Bonnie, Try painting with only one of your paints, like the Neon, for a day or two and see how you feel.  You will likely feel better with some than others.  Get rid of the ones that don’t make you feel good.  Smell is a good indicator, good paints don’t smell strong and few people complain about ill effects when working with them.

What Are You Painting Over?

Dear David,

I am fairly new at painting with acrylics and wonder if there is anything I can put on a finished painting that would remove (or fill in), the brush marks from a previous painting on that canvas?  When the first one didn’t work out, I gessoed over it and wouldn’t you know it, the second attempt was a keeper (except for the brush strokes going in the opposite direction from the first painting).

Thank you for your interesting and informative Art Techniques in Art Avenue Magazine.  I never miss reading it.

Regards, Dianne

Hi Dianne,

Sanding the surface of the original painting and using Molding Paste (sometimes called Modeling Paste) to fill in the cracks is the best way to prevent texture from showing through on your new painting.

Still, it is hard to get a perfectly smooth, uniform finish to paint over even with the best of efforts, especially if a lot of paint/texture was used in the original painting.

Also, it a common practice for artists to put a layer of gesso over an old painting or an area that they want to repaint, but gesso is not well suited for that purpose.  Gesso is a primer coat designed to be used on an unpainted, absorbent surface, like cotton canvas, to which it can readily adhere.  Unlike acrylic paint, gesso has very little adhesive strength and will not stick very well to an already painted surface.  Using white acrylic paint, like Titanium white, instead of gesso, is the best primer to apply over an already painted surface.

Cher David,

My question concerns priming and prepping birch plywood as an oil-painting surface. I have been cutting a sheet of 1/4″ ply into small panels, sanding and putting 3 coats of a good quality acrylic “gesso” on fronts and sides, plus 3 coats of house paint on the backs. This makes a wonderful surface to work on, except it appears as if the finished painting sinks in and becomes matte. I can varnish later on, but am concerned that my support is compromised from and archival perpective. Should I be using another product to seal the plywood before applying the gesso?

Thanks for your advice & your great column, Roz

Hi Roz,

You should seal the plywood first with a good wood sealer, simple Shellac will work the best.  Another alternative is to use Golden GAC 100 medium, it will act as a sealer between the wood and the gesso.  The natural glue in wood (lignin) is acidic and it may eventually discolour the gesso.

I think your painting may be sinking in and looking matte for other reasons though.  The gesso is quite absorbent and will suck some of the binder (oil or acrylic polymer) out of the colors and leave them duller.  Some painters will put a coat of medium on the gesso, sometimes over the drawing, to make the gesso less absorbent.  This first transparent layer of medium, often tinted with color, is called an “Imprimatura”.

Alternatively, like many other painters, you may be diluting your paint with too much thinner (solvent in the case of oils and water with acrylics) this makes the paint dull and matte.  The combination of these two issues would leave any painting looking very dull.

Hope this helps, David

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