Recently I tried to see if alcohol and watercolor would mix. Like, literally. The short answer is no, and the long answer is that it doesn't really like to be mixed, but it seems to yield interesting results.
I tried it out twice, once with the dried watercolor dot samples I have from Daniel Smith, and next with some wet watercolor paint from some tubes I found in the basement.
The dried paint dots were really tricky to work with because it was hard to get any paint to release at all. When I did get some pigment on my brush and painted with it, the effect was really light and washed out. It felt like dry brushing with a wet brush. Very odd indeed.
When I found a bunch of old tubes of watercolor paint, I was excited to see how alcohol would mix with the already soluble paint. It didn't really. The alcohol actually curdled the paint, but since there was more loose pigment, I was able to load up my brush much more than I could from the dry paint. the results I got were darker, but much more streaky.
I wrote a lot more about my experience
on my art blog, but wanted to share at least a glimpse of the process over here too.
I'm not sure watercolor purists would embrace this technique, but it seems like it might be a kinda fun technique to play with when rough textures are called for.