Choosing Acrylic Gels, Mediums & Pastes

by | Jul 2, 2008 | Blog | 8 comments

I often get emails asking about the differences between acrylic gels, mediums and pastes.
First, it helps to understand a general principle behind all paint and painting products.
All colored paints are made with basically two components: pigment – for color, and binder (also called medium, vehicle, and in the case of acrylic paints – polymer) which turns the pigment into a usable paint.

Any other product is usually some form of plain binder without any pigment, and is created to help customize your paint. These are used to change some characteristic of the paint itself, or to change a quality of your painting surface. The gels, mediums and pastes all fit in this category. Let’s start with gels and mediums. Gels are basically thick, while mediums are thin and pourable. Acrylic binder is naturally very thin and pourable. Most people assume acrylic is naturally thick – but it’s not. The thin quality of acrylic or polymer is not made by adding water or diluting. It just is naturally thin. So the gels and thick acrylic paints have thickeners added, while mediums have less thickener, and in the case of Golden’s specialty mediums, have none. (Golden’s specialty mediums are labeled GAC100, GAC200, etc. The GAC stands for Golden Artist Colors). All gloss gels and mediums are clear, while matte products have a finely ground white powder added to them, so they are often slightly cloudy or translucent. Pastes are thick and opaque.

Let’s look at how we could use them:

To change the consistency of a paint mixture you would add up to 30% medium to make it thinner, gel to make it thicker, and a specialty medium (GAC100 or GAC500) to eliminate texture altogether.

To make a colored paint more transparent you would make a mixture of paint with binder, but much more binder than color – about 90% binder and 10% color. You would add gloss gel (if you like texture) or a gloss medium (if you want minimal texture). For a very smooth enamel look use GAC100 or GAC500.

To make any color opaque you would add paste.

To cover over an area in your painting you would apply paste to the area (or white paint).

To create a textured ground use a gel with a knife. Gels have lots of thickener – and you have a choice of varying amounts of thickeners in the soft gel, regular gel, heavy gel and extra heavy gel (which has the most and therefore is the stiffest in handling).

To pour acrylic you would think of using a medium, since these are all pourable. However, there are 2 gel exceptions that are better for pouring: Self-Leveling Gel and Clear Tar Gel are both gels, but are pourable. I add small amounts of water to either of these, and pour over a painting to create a clear, glossy “surfboard” finish. I use minimal handling with these, in other words, I don’t use a brush or knife, but tilt the surface to move the “pour”. GAC800 is also a great pouring medium, and is the easiest to use since it isn’t as finicky as the other gels I mentioned, and will give the smoothest surface as it won’t crevice in fast drying climates – like out here in New Mexico where I live. Adding color is an option to any of these ideas.

My book, Acrylic Revolution, has over 100 acrylic painting techniques using gels, mediums and pastes. Click here to read more and/or order the book at a discount from Amazon.

Nancy Reyner, painter, author and instructor offers assistance to artists in a variety of ways. Click here for more info.

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8 Comments

  1. Glen Martin

    When varnishing a finished painting what is the best sealer to use before applying the varnish: a coat of gel or medium (seems like the medium works with less bubbles?).

    Reply
    • Nancy Reyner

      Hi Glen,

      The word varnish is used is so many ways it can get confusing. For fine art, the word varnish usually refers to a final finishing coat, that is archival. To be archival it needs to have two capabilities. It needs to have UV protection so your colors don’t fade, and most significantly, it needs to be REMOVABLE. The removable quality is necessary because as the artwork gathers dust in its top layer, the only way to clean it is to remove the varnish, and apply a new clean final coat. The best varnishes, then, are ones that are specifically meant for these purposes. Gels and mediums are meant for painting purposes, to mix into paint color, or to apply over a painting surface to change the quality of that surface. They are NOT varnishes, and therefore should not be used as a final coat if you want archival quality.

      For my paintings I mostly use Golden’s Polymer Varnish. This comes in three sheens – gloss, matte or satin. It is non-toxic so I use this if I can. It goes over acrylic but not oil or watercolor. I use Golden’s MSA Varnish, which is toxic because it needs to be diluted with solvent for use, over oil paint.

      One more thing to tell you is that almost always you need to apply something called an “isolation coat” between your finished painting and the final varnish. For this I use a mixture of Golden’s Soft Gel Gloss and water in a 1:1 ratio.

      Here are some articles on the subject from Golden:
      http://www.justpaint.org/tips-and-tricks-for-varnishing/
      https://www.goldenpaints.com/technicalinfo_varnapp
      https://www.goldenpaints.com/technicalinfo_varnapp1
      https://www.goldenpaints.com/technicalinfo_archvarn
      https://www.goldenpaints.com/technicalinfo_msavar
      https://www.goldenpaints.com/technicalinfo_polvar

  2. canvas paintings

    Found your post really interesting and helpful, thanks for sharing.

    Reply
  3. Stacy

    Thank you so much for the specific info and suggestions on creating a transparent color. I love the Golden paints but have a hard time knowing which of the mediums to use, and I have been wanting to experiment with a transparency in some of my work. I ordered the GAC 500 from dickblick!!

    Stacy

    Reply
  4. Nancy Reyner

    Bubbles are an issue! Here is how I keep bubbles out of my pours: If I mix any water or color into the mediums, I mix it the night before I need to use it, let it set to get rid of the bubbles from mixing. When I pour I pour SLOWLY so it doesn’t gurgle out (creating bubbles). I tilt the surface to spread the pour, and use minimal handling with knives and brush.

    GAC800 is easier to use then my formula in the book (I started using it after writing the book). Don’t add any water, and yes, you can add color to it – but only a small amount, about 2 drops color per ounce of medium. After mixing it gently with a knife in a small container, close the container and let it sit overnight before pouring. GAC800 is best poured with minimal handling as well.

    Let me know if you still have problems. Do not use brushes to move it around, use rubber shaper tools or plasterer knives. Move it very gently and only if necessary. Once you apply it do not move the surface until dry. Surface should be level to avoid puddling.

    Hope this helps.
    Let me know if you still have problems.
    Nancy

    Reply
  5. Paula

    Hi Nancy ~

    I’ve tried your faux encaustic method and I’m having great difficulty with air bubbles. I’ve tried making the mixture thinner and letting it set overnight but nothing seems to work.

    I then tried the Golden Acrylic Glaze liquid and had better luck with that but I’ve not attempted to add color to it so I suspect adding the color will again create air bubbles.

    If I use the GAC 800, do I mix it with water or use it straight? Also, what happens if I add color to it? (interference blue and fine gold)

    Is there a specific method you use to add the color that inhibits the air bubbles????????

    HELP !

    Reply
  6. Jo Bradford

    Very interesting – and informative. thanks

    Reply

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About Nancy

Nancy Reyner is a professional fine-art painter with over 30 years experience using a variety of mediums including oil, acrylic, watercolor and mixed media. She has appeared on television for HGTV’s “That’s Clever,” and authored several best-selling painting books with F&W Media. She currently lives in Santa Fe, NM. Read more.
 
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