The greenish tint of untoned Azo has long been remarked. It is easy to "get rid of". In his well-known essay, Michael Smith notes that a 1:125 dilution of sel enium does the job (I seem to need more like 1:45, but no matter). Still, the r esulting tone is not something I'd necessarily be going after otherwise. I don' t think Azo "takes selenium beautifully" as some papers do. The other day, I st umbled onto a funny little book called "Photography Made Easy", which was publis hed in England in many printings/editions between 1900-1930 or thereabouts (auth or "A. Child Bayley" I believe). It has a chapter called "Printing with Gasligh t Paper". The author notes the greenish tint of "certain gaslight papers" and, in order to keep the green down, prescribes developer formulas with very small i njections of potassium bromide (and one or two other adjustments of lesser impor tance). It's interesting to me that the two perhaps best-known amidol-for-Azo f ormulas -- Michael Smith's and the one in Lootens (the two are virtually identic al) -- follow this old recipe in that the P.B. content is very slight (2cc per l iter!); yet, untoned Azo in the Smith amidol developer has the distinct greenish tint. Does anyone understand this? Does anyone use a developer -- esp. an ami dol formula -- that produces a neutral black on Azo? -jeff buckels (albuquerque nm)