I've been paranoid about trying lith printing because my darkroom is poorly ventilated and most of the developer formulas contain formaldehyde in one form or another. See the fruit of my paranoia, a simple formaldehyde-free formula, at http://www.apug.org/forums/article.php?a=171 But then I read a post by Bill Williams on the pure-silver list who noted that two products that remove chlorine and ammonia from aquarium water, ClorAm-X and Amquel, are sodium formaldehyde bisulfite and useful in making lith developer. See the post at http://www.freelists.org/archives/pure-silver/09-2005/msg00213.html. ClorAm-X web page: http://www.aquascienceresearch.com/cloram-x.html In this form, the formaldehyde is apparently not very dangerous - even the notoriously scary City of Tucson Health and Safety page at http://www.ci.tucson.az.us/arthazards/photo2.html goes easy on it. Obviously the sulfite ion binds very strongly to formaldehyde, and appears to turn it into a less harmful form. So my question is: does this happens in a lith developer that contains sulfite and formaldehyde, and does that mean the formaldehyde in the developer isn't as dangerous as free formaldehyde? As I've understood from various postings, the purpose of formaldehyde in a lith developer is to keep the level of free sulfite low, so that infectious development can take place. One would then expect the formaldehyde to be in excess to start with, and be gradually freed from the sulfite ions as these oxidize, producing more free formaldehyde, which speaks against the developers being safe. But on the other hand, one would expect oxidation of sulfite to occur in an aquarium as well, and that doesn't seem to be the case - the maker Clor-Amx says the fish can be eaten after their water has been treated.