There's so many REALLY sharp people on this forum somebody can probably answer my question:

What's the difference (chemically) between plain old "fixer" and "rapid fix"?

I've been sitting here impatiently waiting for some plain old hardening fixer to arrive so I can try my Rockland tintype process - their data says that "rapid fix" will wash out the image - but nobody around here stocks simple fixer, only rapid fix, so I am waiting for my order from Porters to make it's way thru Canada Customs, and waiting, and waiting, and waiting . . . (drums fingers on table)

I have gallons of rapid fixer but not a drop of simple old fashioned fixer. . . .