How to varnish a gouache painting for framing without glass
I’ve often been asked about varnishing gouache paintings and framing them without glass, similarly to oil or acrylic paintings. So, in this post, I´ll describe in detail my process for varnishing gouache paintings, while at the same time preserving their archival properties. I am very excited about this tutorial because being able to varnish my gouache paintings and frame them without glass has made a huge difference for me and it might be a revelation for you too!
What I realized while varnishing my gouache paintings is that varnish restores the true characteristics of the colors. It makes colors look fresh from the palette. In other words, the colors started to look as they had looked before they had dried on the paper and my paintings started to emerge exactly as I had intended them to. I was absolutely amazed at how vivid and rich the colors in my paintings had become when I varnished them.
Varnish makes gouache paintings look very similar to oil paintings and I really like that because even though I love to paint with oils, painting with gouache is pure pleasure and it provides some unique opportunities for exploring color. So, I am glad that now I can use gouache without a compromise and frame my gouache paintings just like I frame my oils.
In this post, I´ll focus on varnishing gouache paintings to frame them without glass and at the same time preserve their archival properties.
If you want to varnish a gouache painting you need to keep in mind that varnish can’t be removed from a gouache painting, so before varnishing your painting you need to be certain that you are happy with it and that you are not going to make any changes to it. Also, make sure you have signed the painting.
Do not forget to take a picture of your gouache painting before varnishing!
Gloss and satin varnishes create a shine on the painting surface which makes it harder to take a good photo.
Your painting should be completely dry when you varnish it. A week in a dry room should be enough for a gouache painting to dry properly.
Support preparation
To varnish and frame your gouache painting done on watercolor paper without glass, you want it to be mounted on an acid-free rigid support like an illustration board, watercolor board or mat board. Thus your painting will preserve its shape in the frame.
You can also use 3 mm cardboard for this purpose but since cardboard is not acid-free it is imperative to seal it on all sides with water-resistant PVA glue before mounting your artwork on it. This glue can also be called wood glue. It protects cardboard from the moisture present in the ambient air and guarantees at least a couple hundred years of life to the painting attached to it. Artists like Degas, Vuillard, Toulouse-Lautrec, Munch, Picasso, and many other master painters have used cardboard. When properly taken care of it can be a very durable painting support.
To mount your gouache painting done on watercolor paper you need to cut off the excess paper. Keep in mind that the frame will cover approximately four millimeters of the artwork on each of the four sides, so you need to leave a little bit of white paper around the painting. Thus the frame will cover only one or two millimeters of the actual painting.
Once you have cut off the excess paper you need to cut a piece of watercolor, illustration board or cardboard of the same size.
Before mounting an artwork on board of any kind I usually seal the board on all sides with a layer of water resistant PVA glue. Thus the painting will be protected from moisture on the back side with the glue and on the front side with varnish.
It’s very important that the PVA / wood glue you use for this is water resistant. I use most often use this water resistant wood glue from UHU:
SUPER WOOD Water Resistant Glue
But you don’t need to use this particular glue. I am sure you will be able to find water resistant wood glues from other brands too.
I have also used Gamblin PVA Size but it stays a bit sticky when it dries, so I like the UHU water-resistant wood glue better.
I usually add one layer of water resistant glue to each of the sides of the board and to all its lateral planes. If the glue is very thick, I slightly dilute it with water. (Gamblin PVA size is very fluid. It doesn’t need to be diluted.)
Now you need to cover one side of the board and the lateral sides with the glue and let the board dry for a few hours. When the board is dry to touch (it usually takes about three hours) you can cover its other side with the glue.
Then you will need to let the board dry for a day before attaching your artwork to it.
Adhering the artwork to the board
Once the board is completely dry, you can attach your gouache painting to it. I usually use a soft gel acrylic medium for this, gloss or matte. It is gentle to paper and it doesn’t bend boards as much as glue does. Any brand of soft gel acrylic medium will work for this. I recommend this Golden Soft Gel Gloss Medium because it can also be used for creating an isolation coat. (More on the isolation coat below.)
“Yes!” glue is also perfect for mounting an artwork on board.
You need to cover the board with a layer of the medium and put your painting on top.
Now, take a plastic sleeve or tracing paper, put it on top of the painting and press your fingers gently against the paper. You can also use a brayer to apply even pressure to the surface of the painting. This process prevents air bubbles from forming between the painting and the support.
Now, you need to put the painting under pressure. A couple of heavy books could serve for that. This will prevent the board from bending during the drying process.
You need to leave the painting under this weight for 24 hours and then you will have to remove the weight and leave the painting out to dry for another day.
I prefer mounting my gouache paintings on board before applying varnish to them because if you varnish your painting first and then start adhering it to a board you can damage the shiny, varnished surface. Therefore, I usually adhere my paintings to boards first and only then do I apply varnish to them.
Ideally, if you are going to varnish your gouache paintings and frame them without glass, it’s a good idea to paint them on pre-made boards. Even better if your board is standard size, so that when the painting is finished you only need to varnish it and frame it in a standard size pre-made frame that can be purchased at any art store.
I love these Strathmore Mixed Media Boards. Dickblick has a huge selection of art boards for wet and mixed media.
Once the board (with your painting attached to it) is completely dry you can varnish the painting.
Varnishing the painting
This is where things get a bit more complicated. If you paint for fun, you can simply cover your paintings with a layer of watercolor varnish and frame them without glass.
However, if you sell your work and want your paintings to be considered archival you need to use lightfast paints, acid-free painting supports, and you need to varnish your painting in the right way, which means that you need to make sure that the final layer of varnish that comes in contact with the ambient air can be easily removed and replaced without damaging the paint layer.
To make this possible with a gouache painting, you need first to apply a layer of varnish that will permanently seal the water-soluble paint surface of your gouache painting and make it waterproof (coat #1, non-removable).
Then, when the varnish has dried, you need to apply an isolation coat to it (coat #2, non-removable). An isolation coat is a non-yellowing, non-removable, clear acrylic medium that permanently seals the surface of the painting and provides a protective barrier for varnish application and removal.
Removable varnish (coat #3, removable), the final, removable coat, should be applied after this isolation coat so that if someone in the distant future would want to remove this varnish and replace it they would be able to do that without damaging the paint surface because the isolation coat would protect the painting.
It would be great if we could apply an isolation coat directly to our gouache paintings and then just varnish them like acrylic artists do, but the problem is that the mediums that should be used to create an isolation coat are all water-based, so we can’t apply any of them directly to gouache aintings because this would reactivate the gouache colors and ruin the artwork.
That's why, to apply an isolation coat to your gouache painting (coat #2), you need to seal the water-soluble paint surface of the painting with a water-resistant varnish first (coat #1).
For the first non-removable coat, only those varnishes can be used that are suitable for varnishing watercolor paintings.
The two varnishes I was able to test directly on my gouache paintings to create this first protective coat are:
1. Krylon Kamar Varnish in the form of spray. I am not a fan of spray varnishes, but if you like using them Golden Archival Spray Varnish can be used for this first coat too (because it is suitable for varnishing watercolor paintings.)
Keep in mind that any varnish applied directly to the surface of a gouache painting can’t be removed.
2. Daler rowney watercolour varnish in a glass bottle. (This varnish can also be called Poster and Watercolour Varnish.) It should be applied with a brush. This particular varnish is very thick and it dries to a crystal clear glass-like finish. Sennelier has a similar product which is called Sennelier Watercolor Varnish. These painted varnishes are based on colorless synthetic resins that do not yellow. To dilute them, if necessary, and clean the brushes after their application only alcohol can be used. These varnishes are non-removable.
Both of the varnishes I have tried (Krylon Kamar Varnish and Daler Rowney Watercolor varnish) are gloss and they have very similar effects on gouache paintings. They make values deeper and the colors more vibrant.
In my demonstration, I used Daler Rowney Watercolor Varnish because I could apply it with a brush instead of spraying it on.
It’s important to use for this first coat only GLOSS varnishes because they are the clearest. If you wish your painting to have a matte finish you can complete the varnishing process by applying a matte varnish as the final removable coat (coat #3).
I prefer painted varnishes over sprayed varnishes because they level out more evenly and have to be applied in a single thick coat. When applying painted varnishes the work has to be placed on a horizontal surface. It will prevent the varnish from running down and dripping.
If you are going to use spray varnishes keep in mind that they have to be applied in light coats two or three times in different directions, until the painting is completely sealed. When applying spray varnishes, your work should be placed vertically for the best result and the spray can needs to be shaken a lot before every use. The painting should be left flat until it dries. You need to let the varnish dry well between layers. Spray varnishes should be applied in a well-ventilated room and you should avoid inhaling the vapors.
Some artists apply wax mediums to their gouache paintings. I don’t think it is an appropriate product for this three-step varnishing method because if you use a wax medium for the first coat the isolation coat might not adhere to it. Wax mediums definitely can’t be used as an isolation coat because they can be dissolved with mineral spirit or turpentine (which are usually used for removing removable varnishes). So if someone decides to remove the removable varnish from the painting they will also remove the wax medium layer. An isolation coat should be resistant to turpentine and mineral spirit for its purpose is to protect the painting in case it is necessary to replace the removable varnish. Wax medium probably can be used as a removable varnish for the final coat, but I don’t think that it can be used for the first and second coats. Also, wax mediums can become softer as the ambient temperature increases. For these reasons, I have never used them.
Coat #1
So now you need to apply varnish varnish to make the paint surface of your painting waterproof. For varnishing, you need to use a clean, soft and flat brush (I use this brush for varnishing - Da Vinci Junior Synthetic Brush - Bright, Short Handle, Sizes 16 or 20)
Before varnishing, you need to clean your painting with a dry, clean, soft brush to prevent dust particles from getting trapped in your varnishing layer.
You need to cover the painting with the varnish gradually. When varnishing a painting this way, you should avoid going back over the already covered areas with your brush. Try to cover your painting in just one layer. Daler Rowney Watercolor Varnish levels out very well, but you need to apply it quickly as it dries fast.
You need to let this first coat dry well for a couple of days before applying an isolation coat to it.
Coat #2
Once the paint surface of your gouache painting is sealed with watercolor varnish, you can apply an isolation coat to it. This coat will create a permanent barrier. Any varnish added after this coat can be removed safely. Most removable varnishes can be removed with turpentine or mineral spirit.
To create an isolation coat you can use either of these two products:
Option one - Golden Isolation Coat. This product is ready for application.
Option two - Golden Soft Gel Gloss medium. For the isolation coat it should be diluted to 2 parts Gel to 1 part water (You don’t want to over agitate it which will introduce bubbles). Only the GLOSS Gel medium can be used for an isolation coat. Matte gels can make your painting look cloudy. Remember an isolation coat is permanent. It can’t be removed.
Golden Soft Gel Gloss medium looks cloudy in the bottle, but after its application it dries to an absolutely clear coat.
When applying an isolation coat you should try not to overwork it. Stop when the entire surface of your painting is still wet. It will prevent bubbles and brushstrokes from being left on the surface of the painting. This approach applies to painted varnishes too.
The isolation coat has to dry well before you apply the final, removable varnish layer to it.
Coat #3
The removable varnish doesn't have to be a specific varnish for watercolor or gouache, but it should be suitable for varnishing acrylic paintings because the isolation coat is basically an acrylic film, so you need to be sure that your varnish will adhere to it.
If you are going to use a water-based polymer varnish (like Golden Polymer Varnish 8Oz Gloss varnish) as your final removable coat, you will need to let the isolation coat dry for about 24 hours. If your varnish is solvent-based, like the one I like to use, you will need to wait about 3 days before applying it to the isolation coat to let the water thoroughly evaporate because you don’t want any water to get trapped under the varnish.
For this final coat you can use either Gloss, Satin or Matte varnishes that are suitable for acrylic paintings.
I like to use Winsor & Newton Artists' Gloss Varnish for this coat. It’s my favorite varnish for oil paintings and it also can be used on acrylic paintings. Golden MS Gloss Varnish is a great varnish too but it should be diluted 3 parts Varnish to 1 part mineral spirit or pure turpentine before application.
If you want your painting to have a matte finish you can use a matte varnish for the final coat.
I was pretty happy with the results I had gotten with Royal Talens matte varnish, but recently I tried another matte varnish which has become my favorite matte varnish. It’s Golden MSA Acrylic Matte Varnish. It is truly matte and it almost completely restores the original matte look of gouache paintings. I love it and highly recommend it. In comparison to it, Royal Talens’s matte varnish appears to have a slightly satin look, not completely matte.
If you prefer water based varnishes Winsor & Newton Professional Acrylic Medium Matt UV Varnish is a good option.
When applying removable varnish try not to brush over the same areas that have already been painted, so that the varnished surface is uniform.
You need to let the removable varnish dry for a day and then you can frame your painting.
You need to simply put the painting in its frames and use a piece of foam core as a backing board.
As you can see this painting looks very similar to an oil painting. I like this because even though I love to paint with oils, painting with gouache is pure pleasure and it provides some unique opportunities for exploring color. So, I am glad that now I can use gouache without a compromise and frame my gouache paintings just like I frame my oils.
Once again, I strongly encourage you to practice the procedures described in this tutorial thoroughly before trying them on a finished artwork.
I hope you've found this information helpful.
These are some of the materials that can be used for this method of mounting and varnishing gouache paintings:
Rigid supports and pre-made art board:
Strathmore 564-8 500 Series Mixed Media Board, Vellum
Canson Plein Air Watercolor Art Board Pad
Crescent Creative Products Crescent Art & Illustration Watercolor Board
Glues and Sizes:
Gorilla Wood Glue (water-resistant)
Titebond II Premium Wood Glue (water-resistant)
“Yes!” glue is great for adhering a painting done on paper to a board.
Gamblin PVA Size - it’s a good size but it stays a bit sticky when it dries.
Soft gels:
Golden Soft Gel Medium Gloss - this gel medium can be used for adhering a painting to a board and for creating an isolation coat. For an isolation coat it should be diluted to 2 parts Gel to 1 part water (You don’t want to over agitate it which will introduce bubbles).
Golden Soft Gel Medium Matte - this gel medium can be used for attaching gouache paintings to boards, but it shouldn’t be used for creating an isolation coat.
Brushes for varnish application:
For small works, I usually use these brushes Da Vinci Junior Synthetic Brush - Bright, Short Handle, Sizes 16 or 20.
For large paintings you need to use wider brushes.
Watercolor Varnishes for the non-removable coat #1:
Spray varnishes:
Painted varnishes (these two varnishes seem to be sold only in the EU and the UK. If you can´t get any of them you can use the spray varnishes from the list above):
Daler Rowney Watercolour Varnish (This varnish can also be called Poster and Watercolour Varnish.)
Sennelier Watercolor Varnish. These painted varnishes are based on colorless synthetic resins that do not yellow. To dilute them, if necessary, and clean the brushes after their application only methylated spirits like denatured alcohol can be used.
Keep in mind that any varnish applied directly to the surface of a gouache painting can’t be removed.
Mediums for creating an isolation coat (the non-removable coat #2):
Golden Artist Colors Isolation Coat - this medium is ready for application.
Golden Soft Gel Medium Gloss - For an isolation coat it should be diluted to 2 parts Gel to 1 part water (You don’t want to over agitate it which will introduce bubbles).
Removable varnishes for the removable coat #3:
Water-based polymer varnish:
Winsor & Newton Professional Acrylic Medium Matt UV Varnish
Solvent-based painted varnishes (these level out better):
Winsor & Newton Artists' Gloss Varnish - the varnish I have used for yeast for oil paintings. This is the one that I removed from the painting in the video.
Golden MSA Acrylic Varnish - Matte
Notice, Golden MSA varnishes should be diluted 3 parts varnish to 1 part solvent. Golden sell their own solvent for this Golden MSA Solvent, but you can as well use pure turpentine or mineral spirit to dilute their MSA varnishes.
Removable spray varnishes that are suitable for varnishing acrylic paintings can also be used for creating the removable coat #3:
Golden Archival Semi-Gloss Spray Varnish
I wouldn’t recommend using Damar varnish as it tends to yellow and becomes brittle with time.
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