G'day Dave,
I usually have to give my boxes 2 coats of paint. The1st I let dry, then apply a really thick coat, as thick as I can without getting runs, and do it fast. I have the flocking applicator all set up and ready to go, I then place the box in a large clear plastic box and start applying the flocking, All this has to be done at a fairly rapid pace as you want the paint to be as wet as possible so the fibres stick. When I have enough flocking on, I put some more on, carefully place the whole thing to one side, over night. The next day knock of the excess flocking or gently blow it of, not with an air gun. It took me few goes before I got results I was pleased with.
Because it is so bloody hot here in the summer, I will only do flocking at night or else the paint dries too quick.
Cheers