I'm writing today to share my thoughts and experiences (which are limited thus far) with gel medium. I don't have many pictures to go over the process but hopefully I can explain a bit about it. When I purchased this there weren't very many articles explaining how to use it other than in single brush stroke folk art ways, and I don't do that, so it was useless to me.
A bit on acrylics in general
To be honest, acrylic paints get some flak in the (already snobby) art community for being amateur or the "chubby crafty wanna be mom" paint of choice, haha. Personally, I love acrylics for their bright colors, cheap price tag, and versatility. I think a lot of the people sniffing down their nose have experienced acrylic paint's inability to mix with water and thus think they are worthless paints. Straight out of the bottle they're pretty much the opposite of oil paints and watercolors, which both have far steeper learning curves. If treating acrylics like watercolor or oil and failing sounds like something you've done, find a gel medium and give it a try.
The purpose of a gel medium
Technically I think this one's (which is the one I bought) intended purpose is to assist in single-stroke folk art (that's even the name brand of the paint I bought) but I bought it because I was looking for some way to make my acrylic paints 1) more translucent and spready (is spready a word? Google's vote is no) and 2) to prevent them from drying too fast. Anyone who has worked with acrylic knows that shit dries as soon as you look at it. Depending on what you're going for, that could be a good or bad thing, but I found that it really hindered my process when I was trying to grow my abilities.
Why you shouldn't use water
Diluting watercolors with water can make some gorgeous artwork. For years I simply diluted my acrylics with water in the same way, but this is a pretty big beginner mistake and no-no. Some small water dilution is fine, but it's easy to overdo it. Too much water breaks down acrylic in a way that makes the end product look ...well, bad. It also causes the artwork to flake or peel or other nasty things, even if it's properly sealed after. The worst part is that if you use water to make a wash underneath, the overabundance of water will cause the acrylic to lift when you paint over it, making layers impossible at best.
What I attempted to do was use the gel medium in the same way I used to use water--to dilute the color and make it spread and glide better. To its credit, it does this so well that I had to really limit my usage of it. The black was so translucent I had to go back over the darker parts several times. This was pretty shocking to me, since even water doesn't really dim the blackness of black. But it was a great experience.
The other fantastic thing was that I could really mix colors on the paper, which is my absolute favorite thing in the world to do. It's haphazard and sloppy, two of my trademark ways to paint, haha. But with just plain acrylic, your mixing time is already on a short clock, and the "fullness" of the colors makes mixing difficult, moreso than with watercolor. I found that for the first time I could pile on color and not have it absolutely destroy what I had done beforehand. But unlike watercolor, which will disappear if you breathe on it wrong, the acrylic colors stayed. Once I got the hang of it, this was the perfect mix for me.
I'm trying to think of negative things to say about the gel medium but I can't...I suppose if you're looking for the brightest colors, and the fastest drying times, don't bother, but for anything else I highly suggest it.