This is a question I get a lot. So I thought I'd post it as a quick reference guide.
Preventing cracking and crazing of your paint.
You have an amazing pouring pattern going, only to check later and it's ruined by paint cracking. How do you prevent this from happening? I've found this can happen for a couple reasons.
1. Are you mixing different brands of paint together? If so, they might not be compatible when combined for fluid painting. Try doing a pour with only paints from the same brand and see if that fixes your issue. That doesn't mean you should only use the same brand in each paint pour, but if you are having problems, that's one potential source.
2. Are you using house paint? I like the idea of being able to buy a gallon of paint for much less than artist paints cost. Especially the Oops Paint Section at Home Depot or Lowe's. Who doesn't love a gallon of paint for $5? But I've found house paint causes all sorts of problems. The cells can often disintegrate while drying. The paint can crack. It dries to a kind of rubbery consistency. After having enough problems using house paint, I gave it up completely. Most regular acrylic artist paints, the kind available everywhere in every city, are generally well suited for fluid art. But try a couple different brands to find out which one works best for you.
3. Is your paint applied too thick? If the pouring consistency is too thick, it can dry with cracks. Or if you put too much paint on your canvas, it will often crack. To correct this issue, thin your acrylic paint with water. Also make sure the layer of paint on your canvas isn't too thick.
4. Drying too fast. Are you drying your artwork using a fan? Is it hot in your work space? Anything that causes the speed of your paint to dry fast, can cause cracking. The solution is to slow down the drying process. You can do that by turning off the fan or moving to a cooler work space.
So generally, too much paint, the wrong kinds of paint, and drying too fast create the dreaded cracking and crazing. Remember, this only applies to acrylic paint.