Best Paintbrushes for Acrylics?

This link should give you some help:

http://www.dixieart.com/FineArts/Silver_Brush_Main_Page.html 

I had a physics professor who said:

"That's not an obvious obvious, but it's an obvious."

Hey, he was a math guy—linguistically challenged.

Yeah thanks.

Hair conditioner, LOL!
That makes sense in a sort of unintuitive yet obvious way.

Probably. I used to do that, and I, too clean my brushes thoroughly. I did notice an accelerated deterioraton of the brushes, though, and once I didn't clean quite well enough…. As I moved more and more to acrylics, the problem became moot. But I recently started using artists' oil washes again, and I'm planning on moving into figures, where I will be using both oils and acrylics. So I just invested in a separate set of brushes for oils and the occasionaly enamel, only.

This is one of those things that you can get away with from time to time—until the time you don't. The worst case scenario would be to use the same brushes with both enamels and acrylics in roughly equal proportions. Much higher risk of something going wrong. For someone who rarely uses enamels (or acrylics), provided they are maniac brush cleaners (always good practice, IMHO) the risk may be acceptably low.

Most of the professional painters (art, architectural, and interior) I have known who used both mediums had two sets of brushes, one for enamels (or oils) and one for aqueous systems. At least one artist I knew had three sets: oil, acrylic, and enamel. 

One tip that can greatly extend the life of any brush is to treat it with hair conditioner before storing, or periodically if you use the brush frequently. For those who "cross-paint," I strongly recommend it.

The short, nontechnical answer is: Yes, even small amounts of incompatible materials will cause a problem, not only on the brush but in the bottle.

For that matter, make sure to rinse the brushes cleaned with Windex thoroughly in water. The ammonia in Windex will play hob with the paint and the bristles.

The reason (vastly oversimplified) only small amounts of a contaminant may cause so much havoc is that reactions involving organic molecules tend to be progressive: a small amount of contaminant reacts with a few organic molecules, changing them to something different. These changed molecules may then react with, or affect the behavior of, the "normal" molecules, and so on. 

Another reason to use separate brushes for both is brush life. When you use the same brush for both systems, the bristles get hit with a "double whammy." The solvents and cosolvents in enamels will slowly attack portions of the bristle structure that are lipophilic ("oil loving"). The solvents and cosolvents in acrylics will attack those portions that are hydrophilic ("water loving"). Using the same brush for both may well shorten brush life by half, and brushes aren't cheap!

That Windex did the trick.

Why is it so critical to not use the same brushes
for enamels and acrylics.  So what if a few microscopic
components of each type come into contact?  Will they
chemically react or something?

espins1 wrote:

Use windex to clean your brushes.  The amonia breaks down the acrylic like nothing else.  Then rinse with water.  Try soaking that brush in a little bit of windex, that should break it all down.

Never would have thought of that.  Thanks espy.  Time to see if i can resurrect my brushes 

You should not use the same brushes for acrylics and enamels. No matter how well you clean them, there is always a microscopic amount of paint left, generally around the base of the bristles, and this will cause problems with a different paint system.

It is also quite likely that your old, reliable brush was nearing the end of its usable service life, and this just put it over the edge. Brushes, even with the greatest care, do not last forever.

Get a separate set of brushes for use with acrylics, save your old enamel brushes for use with oils, or use them for washes and dry brushing.