It solidifies in about 1 hour, but doesn't dry completely for about 3 hours. It also depends on how thick you put it on. If it is very thick it could take up to 6 hours, but if it is thin it could only take 1-2 hours. Try using a blow dryer on very low heat to help it dry faster. That's what I do, and it always works. Make sure to hold the blow dryer about 12 inches away from the paint and keep it moving, don't just blow it on one spot.
Patience is the best method as you may find that it will take about 24 hours no matter how you try to speed up the process.
You can set it out on a dry day, low humidity or use the low setting on a hair dryer.
This thick paint may appear to be dry, but can still be wet under the surface.
Make a small sample with an old shirt and then you will know how long it takes.
If you set the shirt outside, make sure to anchor the corners so the wind does not flip the shirt.
With this you are taking a chance the sun may fade the shirt.
To blow-dry - hang the shirt so air can circulate through the fabric. Put a the shirt on a coat hanger (clip the sleeves out of the way) and then clip a pant hanger onto the bottom and this way you can hold the shirt fairly steady as you use the blow dryer (low setting).
If you hold the dryer too close to the shirt, it can over heat and stop working. Too high speed and the paint may distort.