How To Make Gouache Waterproof Using Wax, Varnish & Resin?
Gouache is a type of opaque water-based paint. It has intermediate qualities to that of watercolor and acrylic paints. When dried, gouache paint provides a soft matt finish. Just like watercolors, gouache can get reactivated with water.
Thus, On one hand, it makes it easy for artists to rework the painting, on the other, it renders the painting susceptible to water damage. Therefore, it is highly advisable to waterproof your gouache paintings to protect and preserve them fresh for a long time.
Are Gouache Paints Waterproof?
The basic gouache composition consists of a binder, which is most often gum arabic, a pigment and water. An inert chalky component may also be present. Gum arabic is meant to give solutions when dissolved with water. They make gouache water-soluble.
The pigment used in gouache has coarser particles than watercolors. And unlike water-resistant acrylic paints, which have acrylic polymers as binders, traditional gouache is not waterproof.
However, acrylic can gouache shows good water resistance. Nonetheless, waterproofing is extremely important. This not only keeps water but also dust, dirt, and UV radiations away.
So, let’s know how to seamlessly waterproof your gouaches artworks.
How To Make Gouache Waterproof Using Wax?
As technical as it might sound, sealing your paintings can be a satisfying task. This is so because the right method can end up making your painting look richer and more vibrant.
Waxing a painting provides a water repellent barrier between the paint and the environment. Waxes can be beeswax (natural wax), microcrystalline (mineral wax), or other kinds of commercial waxes.
They are often mixed with resins to give the desired formulation. Waxes and resins are largely waterproof materials in themselves. They can be directly applied to the gouache without any topcoat.
Most waxes are rubbed on the painting surface, but liquid formulations also exist. Wax coats stay on paintings for a very long time.
In fact, its application has been found to be intact in some very ancient paintings. Besides, waxes are very durable, acid-resistant and leave a beautiful sheen on the painting.
Required material
Step By Step Process
1. Prepare the surface
- Dry the gouache paint. It should be thoroughly dry before beginning the process.
- Applying a little paint on the same kind of surface as the original painting is advisable for a spot test.
- Make sure there’s no dust on the surface to be sealed. Wipe it once with a soft tissue, cotton, etc.
2. Coat
- Take the buffing cotton pad (a soft cotton rag can also be used) and dab a little bit of wax on it.
- Apply on the test spot and with smooth and straight motions, check if the amount of wax is enough. The applicator should be able to glide with minimum resistance.
- Then slowly and evenly coat your gouache painting.
3. Multiple Coats if Required
- Wait for 2-3 hours until the wax coat is dry.
- Dropping a tiny water drop, do a patch test on the test spot.
- Once the coat is firmly dry, water drop will form a bead on the surface without smudging the gouache.
- If required, apply the wax coat a second time.
Precautions
- Using too little wax on applicator might make you scratch your gouache.
- Keep out the painting from excessive heat as the waxes are inflammable.
- The wax might give out toxic fumes, so make sure the place is well ventilated.
Time
Depending on the number of coats and the environment, it may take anywhere from 2 to 6 hours for the gouache before it is sealed perfectly.
Cost
Based on the average prices of the requirements, the total cost might be around $30 which includes $20 for wax coating and 10$ for the applicator.
How To Make Gouache Waterproof Using Epoxy Resin?
Epoxy resin is a type of thermosetting plastic and an ideal choice for waterproofing your gouache.
The waterproof layer it forms on the painting is quite resilient and can be applied on a number of surfaces. It fills in gaps and thus acts as a good sealant. Epoxy resins mainly contain resins, hardeners and plasticizers.
Epoxy resins can be thought of as liquid adhesives. Most of them come in paste-like consistency and a hardener is provided as well. Epoxy resin and hardener are to be mixed in a ratio of 2:1. However, depending on the product this might differ.
The reaction between these two components is termed curing, and it is responsible for the cross-linking of polymers.
Curing heavily depends on the heat of the environment, type of hardener, and size of the surface. Once solidified, the cross-linking renders a clear and thick waterproof layer over your artwork.
Below is a good epoxy resin for gouache:
| Photo | Product | Buy |
|---|---|---|
 | ArtResin - Epoxy Resin - Clear - Non-Toxic - 16 oz (8 oz Resin + 8 oz Hardener) (474 ml) | Check Price On Amazon |
They are meant to be applied on hard panels such as hardwood, MDF, etc., and are extremely durable. Epoxy resins exaggerate the light colors and enhance the look of the gouache.
And, it is important to make sure the end result is devoid of any air bubbles underneath. This is done by providing heat, which makes air bubbles escape out.
Required material
- Epoxy resin (resin + hardener)
- Plastic measuring cup
- Stirrer
- Blow torch
Step by Step Process
1. Prepare the surface
- Before beginning, make sure the gouache painting is panelled on a rigid surface.
- Clean your artwork using lint free cotton pad.
- Tape the edges at the back of the panel which you don’t want to be covered with resin.
2. Make the solution
- Take out measuring cup and pour the resin and the hardener in the ratio as directed on the product.
- Using a stirrer, mix the hardener and the resin slowly and thoroughly in the same direction.
- Keep stirring for a few minutes until the solution becomes crystal clear and streaks disappear.
3. Pour the resin over gouache
- Make sure your painting is elevated some inches above the surface you’re working on (table, for instance). For this, keep the painting on some small rigid support (like a block) so that the edges are accessible.
- Pour the solution very slowly and close to the gouache surface, to minimize bubble formation.
- Make sure you start from the centre and gently spread it out towards the edges using the stirrer.
4. Remove bubbles
- After covering the entire panting, check for any air bubbles. They can easily be removed using heat.
- Use a blow torch, as soon as your finish pouring resin, some 4-6 inches above the painting surface.
5. Let it Dry
- Keep your painting aside and don’t touch until the resin is completely set. This might take around 48 hours or more depending on how cool or hot the environment is.
- Once the resin is set and firm, remove the tape from bottom edges.
Precautions
- It is better to set the resin where there is considerable heat and a regulated environment.
- Using too much hardener will alter the curing time while affecting the final texture.
- Ensure that the curing occurs slow (slow hardener) so that the solid plastic is clear and strong.
- Even though the recommended resin is non-toxic, protect yourself using gloves and mask.
Time
The total procedure will take around 2 days or more, depending on the resin setting time.
Cost
Using this method might cost you the following (approximation):
- Epoxy resin (resin + hardener): $30
- Plastic measuring cup + stirrer: $10
- Blow torch: $15
Total cost: $55
| Photo | Product | Buy |
|---|---|---|
 | KYOKU Refillable Butane Torch Lighter | Check Price On Amazon |
| | ArtResin - Epoxy Resin - Clear - Non-Toxic - 16 oz (8 oz Resin + 8 oz Hardener) (474 ml) | Check Price On Amazon |
How To Make Gouache Waterproof Using Varnish?
Acrylic varnishes form a water-resistant layer over gouache, thereby sealing it. They contain resins, oils, and solvents. All these repel water and thus make up a good waterproofing formulation.
For gouache paintings, waterborne acrylic should be chosen. They don’t yellow over time and flawlessly stabilize the gouache, giving them the hard protective cover. In addition to hard painting surfaces, they are good to go over any flexible surface as well, just like paper.
Acrylic varnishes are set as a permanent waterproof layer on the gouache painting.
On top of non-removable varnish, an isolation coat is required. It is also non-removable and forms a layer between the non-removable varnish and the outer removable one.
Removable varnish is important in the sense that over time dust particles settle and dull the gouache. Hence removable coat allows you to renew the varnish without affecting the paint underneath.
Foam poly brushes are often used to apply varnish coats. They’re suitable with gouache as they absorb more varnish and help in even spread in single strokes.
For the application of isolation coat and removable varnish, quality synthetic brushes can be used.
Required Material
- Acrylic varnish
- Isolation coat
- Removable varnish
- Foam poly brush
- Flat brushes
Step by Step Process
1. Surface preparation
- Dry the gouache painting properly, for around a week.
- Gently clean off any dust using a soft cotton pad or rag.
- Tape the blank sides of the painting to get even edges post varnishing.
2. Apply acrylic varnish
- Make sure the varnish has a watery consistency.
- Dab the wide foam brush with an acrylic varnish, without fully saturating it.
- Paint the gouache with only one stroke on one area. It’s better to use vertical or horizontal strokes.
3. Isolation coat
- Wait for 3-4 days until the varnish is well dried.
- Using a flat brush, apply a thick layer of isolation coat, and don’t overdo. Over application can give air bubbles in the surface.
4. Coat removable varnish
- Wait for a day before the isolation coating is ready for having the final removable layer on top.
- With the help of the flat brush, gently apply, just like you had applied the first layer.
- The next day, your gouache would be dried completely and sealed properly.
Precautions
- The varnish layer should be thin. An extremely thick layer might reactivate the gouache.
- The painting should be kept flat to avoid any drop-downs.
- Varnishing should be done in a well-ventilated area.
Time
Starting with a freshly painted gouache painting, the whole procedure might take around 10-12 days.
Cost
The approximate cost of various items used are:
- Acrylic varnish: $20
- Isolation coat: $15
- Removable varnish: $10
- Foam poly brush: $20
- Flat brushes: $10
Total Cost: $75
Final Words:
Waterproofing gouache is essential to preserve your artworks for a long time. Waxing is cheap, quick and a suitable way for waterproofing gouache in journals or other such personal collections.
Epoxy resin is ideal for waterproofing gouache paintings done on a rigid surface. The hard coat and mirrory sheen they provide, give a clear and finished look to gouache.
The final method of varnishing doesn’t show as dramatic results as the epoxy resin, but is effective with flexible surfaces. Moreover, you’re free to choose any from matte, satin or gloss, to get the desired effect.
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