I did an experiment. I have had a hard time getting a clear, crisp mottle on my babies for over a year, since my favorite brand of wedges changed to the cheaper, porous material. Recently one of our drug stores was liquidating one of their brand of wedges, so I purchased them because they look nice and dense and spongy, almost like marsh mallows in firmness. I plucked some and compared painting with them along with the other brand I’ve had for the past year or so. Night and day difference. The porous cheapened wedges don’t leave a crisp mottle and the mottle pattern blurs out on the vinyl. The crips wedges? Clear mottling without any blurring. I just hope that not all the brands are changing over to the cheap, porous material.