I know it's the crystals. I meant the crystals would not stick to dry paper like that so sometime between printing and applying powder the paper is getting wet or sticky from something. My guess would be moisture collecting on the substrate side of the emulsion due to humidity. Are you spraying or wiping the back of the screen with anything that could transfer to the paper? Is the paper hot enough that it could melt the crystals onto it when applying the powder somehow? Basically, the powder doesn't just stick to dry paper like that. You may get a handful of random crystals here and there, but that is a massive amount of excess powder stuck to the paper.