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What Can I Use to Create A Thick Gloss Varnish Layer on an Acrylic Painting?

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artist squeezing acrylic paint onto palette Christopher Bissell/Photodisc/Getty Images

Question: What Can I Use to Create A Thick Gloss Varnish Layer on an Acrylic Painting?

 

"I normally use an epoxy resin mix to create a thick coat on some portion of my acrylic painting to create a special gloss or glass effect. However, the store that sold that product is now closed and I'm looking for a similar product. I am told that some people use wood floor varnish to create that effect but I am afraid it could turn yellow with time and light. I would try a self-leveling gel but I don't think it will have the same glossy effect." -- Hélène D.

 

Answer:

A DIY product is a bad idea, in my opinion, if longevity is desired. The stuff just isn't made to last, it's made to be redone every five to 10 to 15 years.

I would have thought that an acrylic self-leveling gel would work, but you would need to do multiple layers if you're after a thick coat. And be patient enough to ensure each is thoroughly dry before applying the next.

But to be sure I asked Michael S Townsend at the Technical Support team at Golden Artist Colors for his expert opinion. Here is his response, reprinted with his permission:

Using Epoxy Resins: "There is a trend in the art world to use two part epoxy resins in artwork. These coatings are known to be very appealing because of the uniform, clear glossy coating they create, however, the material has some drawbacks as well. On the plus side, two part epoxies are strong, clear films with excellent leveling. Being two part systems, they cure by means of chemical reaction, with translates into fast drying film that don't 'craze'. These properties make them ideal for floors, cast objects and bar tops.

However the downsides are that they are hard, to the point of being brittle as they age, and they are known to discolor over time as well. We have been looking at some Smooth On products as they have casting supplies. They have a two-part polyurethane. Polyurethanes are not as prone to yellowing, so it should be a better alternative.

"While it is possible to apply a varnish over the epoxy resins to slow the degradation, this coating may change the surface appearance. Golden Hard MSA Varnish with UVLS (less tacky than the regular MSA Varnish, but the regular MSA is a more commonly found product in stores and is still suitable for this use) would be suggested to use over the epoxy resin. There are other topcoats that have UV protection as well that can be used, such as automotive clear coats and a few artist varnishes.

Acrylic Mediums for a Thick Gloss Layer: "Acrylic mediums used to create a deep glossy surface also have their share of pluses and minuses. It is hard to get the exact, perfect look of epoxy with them, so some tool marks, bubbles and a little less of the clear nature of epoxy (before UV exposure). Acrylic are more UV resistant than the epoxy, but over time there can be a color shift, especially more noticeable when used in thick films. They can also craze during drying. They dry by water and additive evaporation, which can be a painfully slow process to someone already using an epoxy resin. The water loss also can cause 'crazes' in the drying paint film if applied too thickly, and this is one of the key problems when using acrylic mediums as an alternative to epoxy resins. However, on the plus side is products such as Golden Self-Leveling Clear Gel and Clear Tar Gel are made with 100% acrylic polymer dispersions, so they are much safer to use overall, and also do not become brittle.

"The artist should at least try using acrylic mediums for this process. The idea is to apply either by brushing, troweling, or even pouring in such a way there are not any tool marks left behind. Multiple coats can be applied to achieve a thicker overall layer, but each individual layer needs to be thin. This helps to greatly reduce the chance of crazing.

"We have a video about using the Clear Tar Gel. While the video shows blending with fluid acrylics, there are some great visuals for someone interested in how these kinds of products are used."

 

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