Here is an edited version of an email exchange I had with an oil painter who had some questions about some oil techniques she is using and the main issue concerned the use of RETOUCH VARNISH.  She is concerned about permanence in her work and wanted to make sure she was using the retouch varnish correctly.  This is a topic I have not discussed so far in this magazine and I know it is one that many oil painters have questions about.

Dear David,

I have been trying to get a scientific answer to the following question for some time. So far all I have is guesses, logical assumptions and refusals of help from some art suppliers because I don’t deal with them. I recently read your gesso and primer advice you gave
in the FCA’s “Art Avenue” under “Art Techniques” and immediately thought: “I may have finally found the guy to answer my question”.  My question is: Can you, or should you, apply a retouch or final varnish over imitation gold leaf once the gold leaf
has been covered by a satin sealer?  I have combined oil and imitation gold leaf on canvas. These are the steps I have taken:
1. applied gold leaf adhesive onto gessoed canvas.
2. Placed the imitation gold leaf on the desired areas.
3. Completed the painting with oil around the gold leaf.
4. Applied a satin sealer to the gold leaf areas.

Now the painting is dry to the touch and I want to apply a retouch varnish to it.  Should the application of the retouch varnish include the gold leaf area or should I isolate the gold leaf and varnish the oil only?  The reason I apply a retouch varnish to an oil painting once it is dry to the touch, is to protect it from dust, smoke, and other air pollutants until, once is it completely dry (6mos.-1yr.), I can apply a final varnish.  During the retouch varnish stage, I can still go back into the painting and make new marks but once the final varnish has been applied, I have agreed with myself that the work is finished.

I would be thrilled if you could give me some straight answers on this – if you need more information please don’t hesitate to email me.  Thanks in advance for any advice you may be able to give.

Regards, Lesley

Hi Lesley,

Here is a straight answer your question:  you should not put a retouch varnish on the gold leaf.  The sealer you describe is probably enough to serve as a protective varnish type layer over the gold leaf.

Retouch varnish is a thinned out version of a final picture varnish used to ‘bring up’ dull areas of the painting where the color has sunken so that you can continue working on a surface with even sheen.  Typically, the picture varnish is diluted approximately 1:1 with a solvent like turpentine to make a retouch varnish.  You may have noticed when working with oils that some colors dry to a more matt finish than others and this variation of sheen between different areas of the image sometimes makes it difficult for painters to gauge values and hues when they resume work.  This is esp. important for portrait painters or those doing subtle transitions of tone and color.  Retouch varnish is meant to be used for this purpose only, not to keep the painting clean.  It should be applied very thin so that it does not form a resinous, continuous layer as this would add a complicated element to the structure of the painting and affect drying.  Also, the retouch varnish should only be painted over once it is completely dry.

I would not be concerned about protecting the painting from pollutants over such a short period, unless you live in an unusually polluted environment in which case I would be more concerned about your own permanence!  Instead, continue to rework the oil painting for as long as you need to and if you like and when it is completely dry you can clean it gently with mineral spirits and a soft rag to remove any dust or grime before applying the final picture varnish.

Hope that helps Lesley.  Cheers, David

Hi David,

I have a question for you. I have a completed
picture that is finished properly with soluvar etc. and I would like to make some changes to it. Do I need to remove the top coats of varnish, or can I just
paint over top of them. If it is possible to remove the top finishes, what would I use? Thanks for any help you can give me.

Yours Truly, Pat

Hi Pat,

yes you can remove the soluvar, and yes you should do so before making changes to your painting.

you haven’t said whether it is an oil or acylic painting.  if it is an acrylic painting i will assume that you have a layer of islolation varnish under the soluvar as the solvent used to remove the picture varnish (soluvar) may damage your acrylic painting.

you should use turpentine or mineral spirits. lay the painting flat and put a rag soaked in the solvent over the painting, or the area that you want to retouch.  let in soak for about 5 min to soften the varnish.  then take a clean rag and rub the surface to remove the varnish.  if it is still sticky after that then repeat the process.  you can get further info on varnishes and varnish removal from the Golden website.  hope that helps.

Hi David: Thanks for the info on removing the finish on
my painting. It worked great.  The painting was Acrylic which I forgot to mention.  I also looked up the Golden site on the Internet.. I have another question for you:  Have you used any of the new Liquid Golden Paints, that can be used similarly to watercolours. I have noticed them at Opus,
but don’t know anybody that is presently using them. Thanks for any help you can give me.

Pat

Hi Pat,

i use the fluid acrylics them and they are awesome.  they are made with a new and special formulation of acrylic binder that is liquid and actually capable of holding more pigment, and that means a higher saturation of color, than heavy body paints.  they are quite intense and really great for using in glazes.  not all of the pigments are available in the fluids, mostly the light weight, transparent ones.  they are a good compliment to your palette if you like to do glazing.

Thanks for the questions, David

I will reprint here an interesting exchange that I had with a friend about varnishing watercolors.  Many people feel that watercolors would be more marketable if they did not need to be framed behind glass.  There are ways that this can be accomplished.  Read on…

Hi David

I have been reading and enjoying your articles, and noticed that J Annesley was asking about water based varnish.  Many firms do make water based varnishes as you know, but their application is more limited – they cannot be applied to oils, for instance. But due to demand by watercolour painters who are sick of dealing with glass, we organised a demonstration of Varnishing your Watercolours. I had learned that there are ways of doing this, then found a teacher in Edmonton who has personal experience doing it. She made the presentation, and a success it was. I managed to catch parts of the session in order to get some impressions for myself, and I am convinced that it can be done, quite easily. In fact, I feel there are many ways to accomplish it, with varied materials. This process
gives the result of a watercolour on paper which is entirely coated with varnish (either water or solvent based) but which looks almost exactly like a normal watercolour. The varnish is not conspicuous nor unpleasant, and the painting should not require glass to protect it. Now we’ll have to see if galleries are willing to accept this new procedure. I feel they should.

One question remains for me – if the rear face of the paper is unvarnished, is it in danger due to
the effects of the atmosphere, and is this a serious consideration. If it is, then one could varnish both sides and ‘encapsulate’ the sheet, with little extra effort.

I feel it could be applied to ink, charcoal and graphite works, tempera and casein as well as watercolour and gouache. If you want to learn more from my original contact person, have a look
at her site at http://www.arletapech.com/Varnishing.html

Hi David,

Thanks for the info on watercolor varnishing.  I will pass it on to the techno fans.  The two main concerns from a conservation stand point to varnishing watercolors on paper are that the varnish would become a part of the painting because the porous surface of the paint would absorb the varnish, and; you would still need to find a way to protect the paper from the rear, as you mention. I think the varnishing method described at the website you gave me is a good idea and no doubt permanent.   The essential factor is the initial ‘isolation’ layer that actually creates a permanent bond between the acrylic resin and the painting (support) itself – I bet that that will make some conservationists nervous, however.  I would say that the top layer of varnish would need to be easily removable (like the solvent based ones).  I would not be concerned about the back of the paper if it is mounted and framed as she describes.  I still have trouble imagining that it will look exactly like an unvarished watercolor though, but it seems like a good alternative to framing behind glass.   Thanks for being such a keen technical guy David,  See ya, David
Edit Note  An internet search entitled ‘varnishing watercolors’ would no doubt provide information about the techniques discussed here.

Many artists are not sure when, why, or how a painting should be varnished.  Let’s have a look at these questions.  If you do a water color painting on paper it is normal to frame it behind glass to protect it.  After all, watercolor paint is not much more than pure pigment with a very small amount of binder.  It has to be protected and there is no way that you could clean the painting without damaging it.  Because oil and acrylic paints have a heavy binder (linseed oil and acrylic polymer emulsion) that surrounds and protects the pigment, it is not as obvious why an additional layer is required to protect the painted surface.  But it still needs protection.   Think of the varnish layer on an oil or acrylic painting like the glass on a watercolor.  You can wipe and clean the glass without harming the painting.  Likewise, a layer of varnish can be cleaned, and the oil or acrylic paint will not be disturbed.

When a painting hangs it collects on its surface dirt, dust, smoke, grease, and various pollutants in the air.  Over the years the accumulation of these elements can cause the painting to look darker or more brown or yellowish.  Some of the dirt may be well imbedded into the surface and will required strong cleaning agents to remove them.  A thin layer of varnish can easily be periodically cleaned or even removed by a professional restorer along with all the accumulated dirt leaving the painting looking as fresh as the day it was painted.  If the dirt is stuck to the unprotected paint layer itself, then removing it may mean damaging the image.  Especially if there are thin, delicate layers of paint or glazes.  The Varnish is meant to be a temporary layer of protection that can be gently cleaned and eventually removed and replaced once it has accumulated too much dirt.  The process of removing the varnish is called “Stripping” and is best done by a professional restorer.

It is common to think that somehow acrylic paintings don’t need a varnish as much as oil paintings do.  This is false.  In fact, the dried acrylic resin is more sensitive to solvents than a dried layer of oil paint.  Moreover, acrylic resin is thermoplastic and electrostatic.  In warm temperatures it becomes softer and more sticky so dirt sticks to it more easily.  Because it is electrostatic it actually attracts dirt particles floating in the air!  The bottom line is if an art work of any kind is exposed to the air it will get dirty and need cleaning and it is better to clean or replace the varnish than to risk damaging the image by cleaning.  Another important point to mention is that some artists like to use oil and acrylic paintings in thin washes, like watercolors.  When this is done the binder (linseed oil or acrylic resin) is diluted so much that the pigment is left virtually unprotected, like a watercolor painting.  In this case it is best to frame these pieces behind glass as you would with a watercolor painting since the addition of a varnish layer would effectively become the binder and then you would not be able to clean or remove it without damaging the paint.

Two Kinds of Varnish

The original varnishes used for oil and tempera paintings were natural resin varnishes like Damar and Copal.  Natural resin varnishes are still used by some artists on oil paintings but should not be used on acrylic paintings because these varnishes need to be dissolved in solvents like turpentine that are normally harmful to acrylic paint.  The new synthetic acrylic solution varnishes are in more common use now and can be used on either acrylic or oil paintings.  They are made with an acrylic resin that is dissolved in mineral spirits rather than water like the paints.  These varnishes are supposed to be non-yellowing, unlike the natural resin varnishes that tend to take on an amber hue over time.

Spray on or Paint on Varnish?

There are certain advantages to spraying your varnish on rather than painting it on, and vice versa.  The greatest advantage of spraying varnish is that it allows you to apply the varnish in a thin, even layer.  Varnish layers should be quite thin so they can be easily removed.  The habit of some painters old and new to pour a thick layer over their work is not recommended.  The problem with spraying varnish is of course the potential health hazard.  You should spray your paintings in a well ventilated space and use a respirator.  The best quality acrylic solution varnishes do not come in spray cans as far as I know, though they can be diluted and used in a sprayer.  When brushing the varnish on use a good quality wide brush that is use only for varnishing.  Apply the varnish in a thin even coat and then without dipping the brush, gently wipe over the varnish to smooth it out and pick up any excess.

Gloss or Matte Varnish?

The choice here has to do mostly with the visual effect sought.  A matte varnish is simply a gloss varnish with tiny transparent particles added to it that deflect the light.  The addition of these particles does mean that the varnish coat will be somewhat less durable and more prone to scratches.  The good quality acrylic solution varnishes come in both matte and gloss and can be mixed in any proportion to achieve the desired effect.  For most images a mixture of between 4- 6 parts gloss to 1 part matte varnish is a good all around varnish.

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