I have about 50 bottles of acrylic paint, all different colors, that I have not used for several years. Some have just about dried up and in some the paint has gotten thick.
Re-hydrating acrylic paint.
Step 1
You can try using a small amount of water on your brush,and mixing with dried paint.
Step 2
You can add acrylic flow improver.Just add a small amount to your paint and stir,repeat until you get the desired texture you want.
I would use only water to rehydrate it.
Some brands like FolkArt® Fabric paints tell you never use water to save old paints, of course, they are trying to sell new paint so you can try.
Put a small squirt onto a palate and add a few drops of warm water.
Some people have success with Gesso (whatever brand you use) so you could try the same technique. A little on a palate, a few splots of the Gesso, mix.
When we were painting we bought cheap paints and they were not savable when we went back to using them. Better paints will refresh better. I just bought cheap, small plastic bottles and they turned to glue.
Post back how it goes for you!
There are mediums sold at all craft stores that will usually work but water will also work.
The big problem is 'how dry'?
It is very difficult to restore really hard dry acrylic paint.
check some of these sites out.
www.wikihow.com/
www.ehow.com/
There are also several instructional YouTube episodes available.
If it's hard-dried, you could cut open the bottle with a box cutter to release the paint onto a heat-proof shallow bowl, add some water, cover, and microwave for a bit (start with 30 seconds).
What if the paint is totally dry like hard rubber? How can I revitalize it.
where can I get acrylic flow improver for acrylic paint tubes