Problem with spotty varnish - WetCanvas: Online Living for Artists

This topic has 26 replies, 10 voices, and was last updated 7 years ago by contumacious.

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April 15, 2017 at 10:51 pm #995021
redjb77
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I have had some issues with my varnish being spotty (shiny and dull). I use walnut oil with alkyd – not heavily, but occassionally to make paint flow. Recently painted a detailed portrait on a linen panel and ended up with some shiny and some dull. the painted was pretty dry – several months and I used a retouch varnish. I am going to try and spray over with a matte varnish to bring down the spottiness. I am afraid the the alkyd may have been the reason. I cannot use any other mediums because of my asthma. Any suggestions to avoid this happening in the future, and perhaps to repair the situation?
April 15, 2017 at 11:54 pm #1268345
WFMartin
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Spotty, glossy-and-dull spots with varnish will definitely not be as much of a problem if you would decide to “oil out” the surface of your dried painting, before applying a varnish to it.

Mix up a an oiling-out solution of one part Linseed Oil to 3 parts Odorless Mineral Spirits. Apply it with a cloth of lint-free T-shirt material. Allow it to soak in for a few minutes, and then buff it off with a dry cloth of the same material.

Allow it to dry for about the same length of time that you would have, after having applied your last application of paint, and then apply your varnish.

Oiling out helps to seal the porosity of the quickly-drying, dark Umbers, while being mostly buffed off of the light colored areas.

If the use of Odorless Mineral Spirits is a problem for you, then I don’t have any suggestions for that, because for me, such material is merely part of oil painting.

wfmartin. My Blog "Creative Realism"...
https://williamfmartin.blogspot.com
April 16, 2017 at 12:04 am #1268346
redjb77
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Thanks for the great suggestion. Any ideas about how to repair the present problem?
April 16, 2017 at 2:39 am #1268363
Gigalot
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I think, that old retouch varnish can cause trouble for oiling out process. It can make linseed oil sticky for a long time and it can collect dust. For me, if you can’t remove retouch varnish, then it might be better to wait one year or two years to let Walnut oil paint to dry properly. When your paint became completely set and bone hard dried, then do normal varnishing using the same kind of varnish you tried to retouch. Use Dammar varnish and apply it using microfiber cloth. Proper varnishing on top of 2-3 years old ABSOLUTELY HARD DRIED painting surface will do the job.
April 16, 2017 at 5:12 am #1268349
AllisonR
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I have both Juliette Aristides’s books Classical Drawing and Classical Painting Atelier, and she gave the best advice ever. She cleans her paintings before varnishing with weakened ammonia. Doing this gives the paint a kind of tooth, which is invisible to the eye, but then causes the varnish to soak in evenly in all areas. And of course your painting is then clean before you varnish it.

Some areas of your painting will have more sink-in (be duller) than others, and varnish will only cover some areas, bead up in others, when applied straight. At least that’s what happens with my paintings. Since I started cleaning first with ammonia I no longer have these problems. The painting must be dry first – absolutely no color coming off. And you need to clean with a lint free cloth – I use a thin sponge like fake cloth that has no fibers. I use gamvar, which I think would be fine for asthma – I have hd asthma and still have eczema (they are related).

Being born places you at a greater risk of dying later in life.
http://www.artallison.com/
April 16, 2017 at 6:15 am #1268351
Ron Francis
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George O’Hannlon recommends against both oiling out and using ammonia.
I believe that Juliette Aristides no longer uses ammonia after learning of its harmful effects from George.

If the varnish is spotty purely because the surfaces are microscopically matte and glossy, then a full varnish will fix the problem, however, if the glossiness is caused by the oil filling in the texture of the canvas, so that those areas are glass like, then varnish won’t hide the differences.

Also, dammar varnish is not recommended by conservators, at least in America, because it yellows and is difficult to remove.

Ron
www.RonaldFrancis.com
April 16, 2017 at 10:41 am #1268350
AllisonR
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George O’Hannlon recommends against both oiling out and using ammonia.
I believe that Juliette Aristides no longer uses ammonia after learning of its harmful effects from George.

Why? What are the details, please. I googled, couldn’t find anything specific about not using ammonia. Except that Sadie Valerie uses windex (which is basically ammonia) prior to oiling out and varnishing.

I agree that dammar is a bad choice, because it cross-links with the paint layer and can’t be removed later. Esp. if you also use dammar in your medium. Gamvar is the way to go, imho.

Being born places you at a greater risk of dying later in life.
http://www.artallison.com/
April 16, 2017 at 11:50 am #1268364
Gigalot
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Also, dammar varnish is not recommended by conservators, at least in America, because it yellows and is difficult to remove.

If the painting is already, but unsuccessfully varnished with retouch varnish, then I do not recommend to use another varnish to mix both substances into one layer. You can do Gamvar varnishing for right prepared and quality dried painting, but I dont think, that Gamvar on top of poorly applied Dammar is good suggestion. Unless conservators tested both varnishes and can recommends to use one on top of another.
However, Dammar retouch varnish + oiling out + final Gamvar varnish all in one painting looks scary for me!
April 16, 2017 at 2:45 pm #1268367
Forestgrass
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I sympathize with you on this. I’ve been trying to take care of it as I paint by carefully adding more medium to colors that tend to sink but with your asthma that may not work for you.

I hope adding a final varnish will fix it as mentioned above. I’ve also heard of people applying extra varnish only to the less shiny areas to make the whole surface consistent, but not sure how they accomplish that exactly.

Spray varnish never works for me – too hard to get even. Matte varnish is tricky I think because it can cloud things but if careful, that may work. Wearing mask while spraying which you probably already know is necessary for anyone but especially with asthma.
April 16, 2017 at 5:22 pm #1268369
contumacious
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I have used Galkyd to oil out a piece that had some serious differences in sheen and it worked great with a single, thin application. It can be used at various stages of painting, as well as at the end to get the final uniformity of sheen you want. When it was done and dry I did a removable final protective varnish with Gamvar.

Oiling Out with Galkyd from Gamblin

Though I have never used any, I avoid retouch varnish based on what I have read or viewed about the possible negative aspects, in a nutshell from the video link – you don’t want an “easily soluble layer within the permanent structure of an oil painting”.
April 16, 2017 at 6:38 pm #1268352
Ron Francis
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Why? What are the details, please. I googled, couldn’t find anything specific about not using ammonia. Except that Sadie Valerie uses windex (which is basically ammonia) prior to oiling out and varnishing.

I can’t tell you the specifics I’m afraid.
I’m a member of the group ‘Painting Best Practices’ on facebook, headed by George O’Hannlon with conservators and industry technicians like Sarah Sands (Williamsburg) and Kristin Deghetaldi (MITRA).
The question of using ammonia on paintings came up very recently and George’s response was that it was a bad idea and said something like “please don’t use kitchen products on your paintings”. This includes onions etc.
Anyway, Sadie’s book and ammonia usage was mentioned and the reply was that she no longer uses it after receiving advice.
Of course memory is fallible. I’ve never used ammonia so I had no reason to take much note, but it was something that stuck in my mind.
I can only presume that ammonia damages the paint film somehow.
If you’re not a member of the group, you can join it and search it for ‘ammonia’, or even ask about specifics.

Ron
www.RonaldFrancis.com
April 16, 2017 at 6:49 pm #1268353
Ron Francis
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If the painting is already, but unsuccessfully varnished with retouch varnish, then I do not recommend to use another varnish to mix both substances into one layer. You can do Gamvar varnishing for right prepared and quality dried painting, but I dont think, that Gamvar on top of poorly applied Dammar is good suggestion. Unless conservators tested both varnishes and can recommends to use one on top of another.
However, Dammar retouch varnish + oiling out + final Gamvar varnish all in one painting looks scary for me!

The original poster didn’t say what type of varnish was used and you may be assuming retouch = dammar.
I don’t know what the advice is on using a synthetic varnish over dammar, but I can’t see it being a problem because synthetics are more easily dissolved in weaker solvents.
I certainly agree that oiling out over varnish would be a terrible idea.

Ron
www.RonaldFrancis.com
April 17, 2017 at 3:12 am #1268365
Gigalot
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I don’t know what the advice is on using a synthetic varnish over dammar, but I can’t see it being a problem because synthetics are more easily dissolved in weaker solvents.

I can agree, in theory it seems to be safe.
BTW, Ron, conservators use a mixture of Toluene + Acetone to remove old Dammar varnish from paintings.
April 17, 2017 at 6:55 am #1268354
Ron Francis
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I can agree, in theory it seems to be safe.
BTW, Ron, conservators use a mixture of Toluene + Acetone to remove old Dammar varnish from paintings.

Pretty powerful solvents! They will dissolve dried paint.

Ron
www.RonaldFrancis.com
April 17, 2017 at 10:39 am #1268368
Humbaba
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Why? What are the details, please. I googled, couldn’t find anything specific about not using ammonia. Except that Sadie Valerie uses windex (which is basically ammonia) prior to oiling out and varnishing.

I agree that dammar is a bad choice, because it cross-links with the paint layer and can’t be removed later. Esp. if you also use dammar in your medium. Gamvar is the way to go, imho.

Art restorer and forger Tom Keating used water with a touch of ammonia for cleaning paintings. In one of his TV shows he demonstrated its use. I tracked down this particular painting a couple of years ago, and the pictures showed it in pristine condition.

In this same episode, he removes copal using strong solvents fron the painting, and finally apply a coat of damar.
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