Hi Everyone! I paint in acrylics and use thin layers of paint, often adding quite a bit of water to my paint. Some fellow artists in my local art club were discussing this techinque and told me that they had read somewhere that adding water to acrylics will cause the paint to break down over time and the painting will not "hold-up" long term. Does anyone know if there is any truth to this?

Raech

I don't think that "acrylic gel" is the best thing to use for "thinning" the paint as it comes from the tube or jar. It's perfectly okay to use gel, if that's what your painting style demands.

I prefer using acrylic "medium" or "varnish" - the two terms are interchangable for the most part. That way your mixing in a liquid that is essentially the same consistency as the paint itself - no need to add water. I instruct my students to use the varnish/medium FIRST and to thin with no more than about 50 percent water if they still find their paint needs further thinning.

Thinning with only water will cause the paint film to be weakened, but the good news is that acrylic is very forgiving. I doubt that it will fall off the support once a final varnish is applied when the painting is completed.

Hi Love 2 paint.  I just experimented with applying an acrylic medium gel over my canvas-kind of heavy-then painted as if it was wet on wet and it worked very well for me. 

Barbara

I feel compelled to emphasize that CLEAR ACRYLIC can be purchased in several forms:

1.  As a very watery varnish sold commercially under various brand names. The one I use is made by MINWAX and is labeled "Polycrylic Varnish." Note: it's intended for use as a "varnish" or protective coat but can also be used as a "medium" and mixed with tube/jar colors of acrylic to thin them. It is watery-thin and thinner than the Acrylic Medium, discussed in 2., next.

2. Acrylic Medium - also sold as a final "varnish" - which is sold under the same trade names as the paints and specifically formulated for use in thinning the paint colors. The varnish CAN be used in place of the medium, but usually has other additives that give it properties suited to its use as a final protective coating.

3. Acrylic Gel - a thickening agent intended to ADD BODY to the tube/jar colors, not to be used for "thinning" as is done with mediums or varnishes. It makes little sense to purchase the gel instead of the medium, and then thin the gel to use like a medium, although it's certainly possible to do it that way.

4. Acrylic Molding (Modeling) Paste - even thicker than the gel - and used to build even thicker paint layers than the gel.

While "thinning" usually implies making paint MORE FLUID, all of the above will work to "extend" the usefulness of a dab of color since they are all transparent once they dry - so if "extending the color" is what some people mean by "thinning" then yes, all of the above will give that effect - but with differences in the resulting film thickness once they have dried