Spotting on Rives BFK

I have been trying to do some palladium prints on Rives BFK. This paper wants an acid pre-treat; I gave it a good 10-minute pre-bath in 5% Oxalic Acid. I'm still getting little blotchy areas


Is this something caused by needing to soak longer, or use more concentrated acid pre-bath, or is this a paper problem?

I have had problems with this paper for several years now, even in a 10% Oxalic bath. I've recently found that Sulfamic acid is really the bees knees and works wonders with a couple of my favorite papers. I'm seeing 1.4+ dmax on some papers. I am looking forward to trying Rives in Sulfamic as I'm guessing this will solve the problems. You can find more info on the altprocess list.

You can find it at Home Depo if you want to do a quick try.
http://www.homedepot.com/p/TileLab-16-oz-Sulfamic-Acid-Cleaner-TLSAC1/100171510#.UgOtzJKsi-0

Mixes up a gallon.