I hope I don't come across as a smarta$$ I'm trying to understand. The white ink is laid down as a first layer and then the colors are laid down? #1 Isn't the white layer supposed to be somewhat dry before the colors? #2 does the white have fibers in it or are the shirt fibers, colored white by the first printing getting hard and poking through the color layer? And #3, is there any way to like just run a household iron over the white to get any stray fibers to lay down between the white and colored print sequence? Whew, getting finger cramps tryimg to understand this.
Ok I will try to answer this for you

the fibers get white from the white ink, and no it isnt dry before the color is applied. The 2 layers are printed one on top of the other without any drying in between.
The white ink does not have fibers in it. If the pretreatment is not applied properly you will get fibrilation, where the fibers of the shirt will stick up thru the image. The way I handle this is to brush down the fibers once I spray the pretreat on. Then when I dry the pretreatment I press first for 15 seconds with a parchment paper, then I remove the parchment and press an additional 10 to 15 seconds. This assured the fibers are lying down well and leaving a smooth printing surface.
As far as using a iron to iron down the fibers between printing layers, the answer is no

That would not work because the white ink is not cured yet. all you would end up doing with this is smearing your image as the ink is wet.
Hope this helps to answer your questions
