Chemicals - pure vs technical

I'm thinking about getting some formaldehyde and potassium dichromate I want to use for their most common photographic purposes.

Are 'histology grade' formaldehyde and 'technical grade' dichromate good enough for photography or should I pay more (twice as much) and get the pure stuff?

The cheapest grade you can find is usually perfectly adequate. Many of use buy much of our chemistry at the swimming pool supply store or the super market. Look at caffenol - I've never seen reagent-grade coffee.

TTBOMK, technical grade is better than, or on a par with, photography grade.