Yes, this box does say single weight. Why would one use single weight if it curls etc. so much easier?
Some papers such as Azo are only made in single weight. I don't know that single weight curls anymore then double weight papers at least in my experience. The Classic Polywarmtone paper sold by JandC Photo (site sponsor) is a triple weight paper.
I would also strongly second what others have said about using fiber paper
for their fine work.
So, when I end up doing more fiber, what print washer would you recommend? Prefferrably something I can find used on ebay or somewhere?
I like the washers that are patterned after the Zone VI design. I bought my last washer used on Ebay. I built my first washer by patterning it on the Zone VI design. It is still in use today.