To me, it does indeed sound like the paper isn't coating as well as others. The spotting sounds similar to air bubble issues we experienced at first. I'd recommend getting a sample of the dry powder and giving it another shot. When using the dry powder, you only need a little bit to spread about and I find it easier to see the sheen on the paper as well as avoiding any sort of contamination. the increase in DMAX is very apparent when we first used Stonehenge, which isn't a heavy weight paper. Let me see what we can find regarding COT 320.