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sulfite solution and hydroquinone
Hi All,
While going through an old book on Photography by L.P.Clerc(Photography: theory and practice), I came across the following interesting piece: "Sulfite solutions do not keep well, therefore preparation of solution is not advised. If absolutely necessary, a 20 percent solution can be prepared and a small quantity (5 %) of either p-aminophenol or hydroquinone can be added to protect the sulfite solution." I forget the exact words, but the above is the essence. I am really surprised. I have always assume that it is sulfite that protects developing agents like hydroquinone and aminophelos, and here I see the opposite. So when we prepare D-76 and D-72, are we protecting the hydroquinone or the sulfite!!?? rgds, Sreenath |
sulfite solution and hydroquinone
On Jun 19, 3:50 am, sreenath wrote:
Hi All, While going through an old book on Photography by L.P.Clerc(Photography: theory and practice), I came across the following interesting piece: "Sulfite solutions do not keep well, therefore preparation of solution is not advised. If absolutely necessary, a 20 percent solution can be prepared and a small quantity (5 %) of either p-aminophenol or hydroquinone can be added to protect the sulfite solution." I forget the exact words, but the above is the essence. I am really surprised. I have always assume that it is sulfite that protects developing agents like hydroquinone and aminophelos, and here I see the opposite. So when we prepare D-76 and D-72, are we protecting the hydroquinone or the sulfite!!?? rgds, Sreenath One problem with Clerk is that there are no attributions or citations. Sulfite slowly absorbs oxygen becoming Sodium Sulfate. In a developer or fixing bath its affinity for oxygen is used to protect other chemicals by preferential absorption. Hydroquinone and Metol are also oxygen absorbers but, like you, I've never heard of adding any to a Sulfite solution to preserve it. Generally, the more concentrated a sulfite solution it the longer it will last. Probably the best way to preserve a sulfite solution is to keep it in a closed, sealed container of some material which does not allow air to pass through. Glass is best but some high density plastics are nearly as good. The various editions of Clerk's books have a lot of good stuff in them but, IMO, the lack of citations and references severely limits them. -- Richard Knoppow Los Angeles, CA, USA |
sulfite solution and hydroquinone
Richard Knoppow wrote:
One problem with Clerk is that there are no attributions or citations. Sulfite slowly absorbs oxygen becoming Sodium Sulfate. In a developer or fixing bath its affinity for oxygen is used to protect other chemicals by preferential absorption. Hydroquinone and Metol are also oxygen absorbers but, like you, I've never heard of adding any to a Sulfite solution to preserve it. Generally, the more concentrated a sulfite solution it the longer it will last. Probably the best way to preserve a sulfite solution is to keep it in a closed, sealed container of some material which does not allow air to pass through. Glass is best but some high density plastics are nearly as good. The various editions of Clerk's books have a lot of good stuff in them but, IMO, the lack of citations and references severely limits them. The only copy of L.P. Clerc I have seen is an English translation in two volumes. These seem to be intended for English students who want a career in photography. I know some color illustrations (all of them) are missing, though referred to in the text. Could it be that a French edition would contain the citations? L.P.Clerc was a scholar, among other things, and it seems unlikely that he would have left out the citations. -- .~. Jean-David Beyer Registered Linux User 85642. /V\ PGP-Key: 9A2FC99A Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 08:25:01 up 7 days, 13:25, 3 users, load average: 4.47, 4.26, 4.15 |
sulfite solution and hydroquinone
"Jean-David Beyer" wrote in message news:5vQdi.3275$lY5.1258@trnddc07... Richard Knoppow wrote: One problem with Clerk is that there are no attributions or citations. Sulfite slowly absorbs oxygen becoming Sodium Sulfate. In a developer or fixing bath its affinity for oxygen is used to protect other chemicals by preferential absorption. Hydroquinone and Metol are also oxygen absorbers but, like you, I've never heard of adding any to a Sulfite solution to preserve it. Generally, the more concentrated a sulfite solution it the longer it will last. Probably the best way to preserve a sulfite solution is to keep it in a closed, sealed container of some material which does not allow air to pass through. Glass is best but some high density plastics are nearly as good. The various editions of Clerk's books have a lot of good stuff in them but, IMO, the lack of citations and references severely limits them. The only copy of L.P. Clerc I have seen is an English translation in two volumes. These seem to be intended for English students who want a career in photography. I know some color illustrations (all of them) are missing, though referred to in the text. Could it be that a French edition would contain the citations? L.P.Clerc was a scholar, among other things, and it seems unlikely that he would have left out the citations. -- .~. Jean-David Beyer Registered Linux User 85642. /V\ PGP-Key: 9A2FC99A Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 08:25:01 up 7 days, 13:25, 3 users, load average: 4.47, 4.26, 4.15 I have several editions of Clerk, all English translations. The forward indicates that citations were delibrately left out to reduce the size and cost of the book. I am quite sure they didn't exist in the original French editions. There are a few citations in the text, mostly just to names, with no indication of where to find them, so its very difficult to trace down original sources. The first two or three editions were published in a single volume. Then the book was taken over by Focal Press who broke it up into several small books. Focal tends to do this sort of thing. Clerk remains a valuable book but the value is very much reduced by the lack of references. -- --- Richard Knoppow Los Angeles, CA, USA |
sulfite solution and hydroquinone
This is 2nd English edition, and L.P.C does state in the foreword that
references have been intentionally left out. I searched through the book again, and found that the original paper is by Lumiere and Seyewetz, 1905. Here is the exact text : "It should, moreover to be noted that several developers, particularly HQ and paraminophenol), if added i very minute quantity to a solution of sulphite, retard very markedly the oxidation of the latter by oxygen of the air(Lumiere & Seyewetz, 1905). They probably oppose the catalytic action of various metallic salts, especially copper salts, which may be present in quantities so small as to escape detection" In another page, he states the quantity of developer to be added as 5 gr ( I think grains) to 20 Oz of sulfite solution. Perhaps this is no longer of practical significance. I find this book really fascinating. thanks, Sreenath On Jun 20, 3:56 am, "Richard Knoppow" wrote: "Jean-David Beyer" wrote in message news:5vQdi.3275$lY5.1258@trnddc07... Richard Knoppow wrote: One problem with Clerk is that there are no attributions or citations. Sulfite slowly absorbs oxygen becoming Sodium Sulfate. In a developer or fixing bath its affinity for oxygen is used to protect other chemicals by preferential absorption. Hydroquinone and Metol are also oxygen absorbers but, like you, I've never heard of adding any to a Sulfite solution to preserve it. Generally, the more concentrated a sulfite solution it the longer it will last. Probably the best way to preserve a sulfite solution is to keep it in a closed, sealed container of some material which does not allow air to pass through. Glass is best but some high density plastics are nearly as good. The various editions of Clerk's books have a lot of good stuff in them but, IMO, the lack of citations and references severely limits them. The only copy of L.P. Clerc I have seen is an English translation in two volumes. These seem to be intended for English students who want a career in photography. I know some color illustrations (all of them) are missing, though referred to in the text. Could it be that a French edition would contain the citations? L.P.Clerc was a scholar, among other things, and it seems unlikely that he would have left out the citations. -- |
sulfite solution and hydroquinone
sreenath wrote:
This is 2nd English edition, and L.P.C does state in the foreword that references have been intentionally left out. I have the 2-volume Amphoto edition edited by D.A.Spencer -- the one published in USA in 1973 and copyright in 1970. This has no Forward, but it does have a Preface by Spencer. It is Spencer who says that the references have been left out (to save space). He does not say the color plates have been left out, though they have been left out even though they are cited in the text. I think the omissions are due to the English editors trying to appeal to English trade-school students, rather that to Clerc himself (though this is just my opinion). -- .~. Jean-David Beyer Registered Linux User 85642. /V\ PGP-Key: 9A2FC99A Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 06:20:01 up 13:55, 3 users, load average: 4.27, 4.11, 4.03 |
sulfite solution and hydroquinone
"Jean-David Beyer" wrote in message news:ytsei.3674$tI5.2965@trnddc08... sreenath wrote: This is 2nd English edition, and L.P.C does state in the foreword that references have been intentionally left out. I have the 2-volume Amphoto edition edited by D.A.Spencer -- the one published in USA in 1973 and copyright in 1970. This has no Forward, but it does have a Preface by Spencer. It is Spencer who says that the references have been left out (to save space). He does not say the color plates have been left out, though they have been left out even though they are cited in the text. I think the omissions are due to the English editors trying to appeal to English trade-school students, rather that to Clerc himself (though this is just my opinion). -- .~. Jean-David Beyer Registered Linux User 85642. /V\ PGP-Key: 9A2FC99A Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 06:20:01 up 13:55, 3 users, load average: 4.27, 4.11, 4.03 This is also true of the english translation of Eder's history. The original German edition had many illustrations which were left out. They were included, or others substituted, in the Dover reprint. I am they were left out of the english translation to lower the costs and Focal does seem to target trade school students with many of its books. -- --- Richard Knoppow Los Angeles, CA, USA |
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