Quote Originally Posted by pdeeh View Post
i've seen formalin substituted for paraformaldehyde in some formulae, which is quite simple to obtain in the UK
Formalin is just another name for paraformaldehyde in solution. However, formalin is just as difficult to obtain - Try asking for it in any high street chemist here in the UK...

I've also seen acetone suggested as a substitute - The function of paraformaldehyde/formalin is to react with the sulphite in the developer and results in an increase in the PH (google for formaldehyde-sulphite clock reaction). Acetone also produces a clock reaction that raises the PH, but it does not get anywhere near the level needed for a lith developer. Another reason for not using acetone is it damages many plastics found in the darkroom.