I have a project coming up for some black foam polyester trucker caps with a white print on the front. I was going to do a heat transfer, but i just did a test, with a white poly ink, and the print is coming out faded. What can i do to make it bold and bright?
By faded, I assume that you mean not opaque, which, in turn means not enough ink (at least not enough on the surface)
So, you are either not making an opaque enough transfer, or you are driving it into the fabric with too much heat, pressure, or time.
Back when I was doing these regularly, I used a regular low bleed ink, through an 83 screen. This was before I knew anything about EOM, so now would probably do fine with a little higher mesh count, and a lot more stencil! My rule of thumb on opaque plastisol cap transfers was one step coarser mesh than direct print.
btw, white was a cakewalk compared to yellow.
Nowadays, I use cad-cut films whenever practical.