Is Isolation Coat Necessary for Acrylic Painting?

I’ve found that there is no full answer to many beginners struggle with the isolation coat. In fact, it’s a process that can easily be your good painting practice if you’re aiming to enjoy your painting for long years.

Is an isolation coat necessary for your acrylic painting? The isolation coat is not ultimately necessary but is highly recommended to protect the finished painting before varnishing and to make it last longer.

Is Isolation Coat Necessary for Acrylic Painting?

In fact, there are 3 reasons why an isolation coat is important especially for acrylic painting. It is a key article before you varnish and finish any of your paintings! You will learn the side effects of not using an isolation coat, the 6 best products, and some tips from an experienced artist.

Table of content:

What is an isolation coat?

An isolation coat – is a transparent protective coat between your finished acrylic painting and varnishing to physically separate them.

It is mostly used with acrylic paintings.


Why isolation coat is necessary?

My experience and research show that the isolation coat is vital for acrylic painting for 3 reasons:

  1. The isolation coat is applied before varnishing to protect your painting. First of all, an isolation coat will create a sealed surface.
  2. Colored wash or stains can contain fewer pigments in the binder, which means these areas of your painting will be extremely fragile and it could also lead to paint lifting. To avoid it, an isolation coat is necessary.
  3. But more important is that it will protect your acrylic painting when you will remove the varnish. Without any isolation, your paint pigments will be also removed, but also, chemicals contained in varnish removals can damage the painting.

But why exactly you need to remove varnish? Well, if you want your painting to last longer, it is recommended to remove and replace the varnish every 5-10 years (depending on the state and environment).

So without an isolation coat, you make your painting last only 5 years.

Another reason why you may need to remove varnish (which means you absolutely need an isolation coat) is when you apply varnish onto a finished painting and when it’s drying you realize that it became cloudy, sag, or even produced some bubbles. In this case, you will remove it and replace it. But be very aware that some of the varnish products are non-removable! 

Once you have applied an isolation coat, you are safe and you can re-varnish the cloudy area or just replace the varnish every 5-10 years.

Insider tip: removing varnish is not an enjoyable process. 
Make sure you made some test before applying it on your painting and you didn't forget anout the isolation coat.

After all, a painting with an isolation coat and varnishing will always look more professional, be more enjoyable to admire due to even surface and cost more.


What can I use for an isolation coat on acrylic paint?

There are gloss, matte or satin mediums:

  • Gloss mediums are the most crystal clear, and the least disruptive to the appearance of colors. Gloss mediums are most recommended.
  • Matte mediums will dull the vibrancy of colors and successive layers of matte medium will begin to look milky or foggy (This can create a moody, encaustic-like effect which can be great if you were expecting it, or potentially devastating if you were not.) 

If you don’t want your painting to be glossy, you can apply matte or satin varnish onto your glossy isolation coat. It will help you still have a very clear look but without inappropriate gloss.

Here are 6 affordable and recommended products you can use as isolation coat:

What can I use for an isolation coat on acrylic paint?
6 products to use as isolation coat for acrylic painting
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Brand NamePriceNotes
Golden Isolation Coat$14.41-$31.39Softer than regular gel, won’t hold a sharp texture but still shows brush strokes. Thinner than a regular polymer medium. Glossy
Golden Soft Gel Gloss$13.70-$78.68Clear drying. Glossy. Very popular among painters.
Delta Creative Clear Acrylic Sealers$8.29-$14.30This is a spray: matte and gloss. Protect from yellowing. But could be an eye irritant.
Golden Acrylic Glazing Liquid Gloss$10.97-$21.95Has longer working time than typical acrylic mediums. Dries slowly. More for fine art and creating glazes or faux finishes.
Golden Clear Leveling Gel$10.19-$65.87Good for textured paintings. Create a smooth surface with no brush strokes
Golden Gloss UV Topcoat$25.91-$34Good for textured paintings. A regular gel with added UV protects paintings from fading

How to apply the isolation coat: 5 easy steps

Before we move on to step-by-step process, remember these 8 rules about applying isolation coat:

1. You apply isolation coat consciously, quickly and carefully 
2. Your painting is fully dried (at least 24h) before isolation coat application
3. There is NO brush hairs on the surface before isolation coat application
4. You've signed your painting before isolation coat application
5. You apply isolation coat in a dry, dust-free room and you use only clean brush and any other containers if you need them.
6. Apply only one coat of your isolation medium and wait 24-72 hours before varnishing.
7. If you need a photo of your painting without patches of reflected light, make it before isolation coat
8. Avoid thick layer of isolation coat by any mean! 

Now we are ready to proceed. The way how you apply the isolation coat is fully depending on the texture of the painting.

Step-by-step guide How to apply isolation coat on your acrylic painting:

Follow all 5 steps to apply the isolation coat on the acrylic painting.

  1. Prepare the isolation coat medium

    Prepare the isolation coat medium if you’re using soft gel gloss, the pre-mixed isolation coat is ready to apply.

    Mix 2 parts soft gel gloss to 1 part distilled water. Mix more than you think you will need. These are recommendations for Golden gel gloss, but you should follow the instructions on the gloss medium or gel gloss that you’ve chosen.

    Little by little add some water to mix it better, but do not add too much! The consistency should be thick.

  2. Prepare the surface

    Prepare the surface on which you will apply the isolation coat. Make sure your table or floor is well protected.

  3. Application

    Using a wide clean brush (the one you know will leave no strokes or hairs) apply the isolation coat on your painting side to side, but never go over just painted and semi-dried areas! You need to work quickly.

  4. Check the surface

    With an almost dry brush (clean the excess of the isolation coat mix) go over the painting to make sure there are no lifted areas. Look at the reflection at an angle to see if you have missed anything.

  5. Let it dry

    Dry 24-72 hours before varnishing.


6 more tips for applying an isolation coat

A textured acrylic painting: it is recommended to use a spray to prevent foam formation. If you’re still using a brush, apply about 1.5-2.5mm thick of the thick isolation coat, do not use a fluid medium because it can create bubbles if brushed.

If you have colored wash or stains: it is recommended to use a spray to prevent fuzzy paints.

You were waiting more than 2 weeks before varnishing: wipe your painting with a soft lint-free cloth before applying varnish.

The optimal thickness of the isolation coat for smooth paintings: is 0.5-1.5mm.

If you want a very even surface with no brush strokes: after applying the isolation, use a foam rubber brayer to roll over the wet coat and to smooth the surface.

If you are coating the sides of canvas: place something under each corner of the painting, this way it will not stick to the surface below.

Here is also a product information sheet about isolation coat by Golden.

Can you paint over an isolation coat? I’ve never done that and will avoid doing it, but I know that some artists leave paintings with an only isolation coat to repaint them later. It won’t be easy because an isolation coat is not a perfect surface to paint on, but still. It will be even less easy to remove the paint you apply over the isolation coat.

Can an isolation coat be left without varnish on an acrylic painting? You can do it, but I do not recommend it. The varnishing protects the acrylic paintings from yellowing, UV, and dust.

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