Archived posting to the Leica Users Group, 2003/04/02
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Specks in Xtol can spell trouble, but often they don't. Phenidone is an excellent surfactant, but not very soluble in water. Ascorbates are soluble, but are not surfactants at all. More soluble developing agents exist, such as p-Phenylenediamine, but it is a slow, physical developing agent because it is _so_ water soluble (it acts as it soks into the emulsion rather than acting on the surface). When you dissolve Xtol and see little specks, it is usually undissolved phenidone (when it isn't, I am not sure what it is - with some tap water it is undoubtedly a precipitate from a chemical reaction you've started in the developer); if an insufficient amount has gone into solution, the developer does not act evenly over the surface of the hydrophobic emulsion and you can get spots. Mixing with distilled water at the upper end of the Kodak-preferred temperature range, helps, as does allowing the developer to sit overnight before use in a full, sealed bottle. Rodinal is okay, but the curve of most films developed in it usually shows a dip that equals slightly depressed mid-tones. If you decide not to use Xtol, I don't think Rodinal is a substitute. _____________________________________________________________ Get your Free Global name@sharkattacks.com e-mail address at http://www.sharkattacks.com _____________________________________________________________ Select your own custom email address for FREE! Get you@yourchoice.com w/No Ads, 6MB, POP & more! http://www.everyone.net/selectmail?campaign=tag - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html