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Keeping qualities of low-sulfite, metol-based film developers
Is a certain concentration of sodium sulfite critical to the keeping
qualities of developers that use metol as the only reducing agent? To put the question in context, consider a hydroquinone-free variation on DK-50: metol 6g sodium sulfite 30g sodium metaborate 10g postassium bromide 0.5g water to make 1 liter With the relatively low sulfite level of 3%, would such a developer be less stable in storage (in full glass or nalgene bottles) than D76H or D23, which call for 10% sodium sulfite? If so, what is the minimum level of sulfite required for good keeping qualities? |
#2
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Keeping qualities of low-sulfite, metol-based film developers
Brad Dow wrote:
Is a certain concentration of sodium sulfite critical to the keeping qualities of developers that use metol as the only reducing agent? To put the question in context, consider a hydroquinone-free variation on DK-50: metol 6g sodium sulfite 30g sodium metaborate 10g postassium bromide 0.5g water to make 1 liter With the relatively low sulfite level of 3%, would such a developer be less stable in storage (in full glass or nalgene bottles) than D76H or D23, which call for 10% sodium sulfite? If so, what is the minimum level of sulfite required for good keeping qualities? I work with sulfited metol developers with and without carbonate. In fact a few days ago I finished testing several small bottles of year ago carbonated mixes. Nearly all were at or near full strength. I'd suggest you brew up that or a portion of the above formula. Give it a few days in the bottles then test using a one quarter portion of that used on a roll of film; perhaps 125ml at film strength. Test with a sheet of 5 x 7 paper. Note the induction time. That is the time for first appearance of an image. It is a measure of the developer's activity. Test again at some latter times. You may find it a good although slow print developer. Add carbonate to speed it up. Results will be similar to Ansco 120 even without the carbonate. Dan |
#3
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Keeping qualities of low-sulfite, metol-based film developers
In article om,
"Brad Dow" writes: Is a certain concentration of sodium sulfite critical to the keeping qualities of developers that use metol as the only reducing agent? To put the question in context, consider a hydroquinone-free variation on DK-50: metol 6g sodium sulfite 30g sodium metaborate 10g postassium bromide 0.5g water to make 1 liter With the relatively low sulfite level of 3%, would such a developer be less stable in storage (in full glass or nalgene bottles) than D76H or D23, which call for 10% sodium sulfite? If so, what is the minimum level of sulfite required for good keeping qualities? I can't answer your question with respect to the developer you mention, but Patrick Gainer has created some interesting NO-sulfite developers with excellent keeping qualities. Most of Gainer's developers are phenidone/ascorbic acid (PC) developers, though. Specifically, PC-Glycol is made from phenidone and ascorbic acid in glycol with a separate solution of carbonate. (The two are mixed together at time of use.) PC-TEA consists of phenidone and ascorbic acid in triethanolamine (TEA), which acts as both a solvent and an activator. Check http://www.apug.org/forums/showthread.php?p=255352 for details. IIRC, metol is soluble in propylene glycol but not in TEA. Thus, you might be able to cross your DK-50 variant with PC-Glycol to get something similar to DK-50 with excellent keeping qualities. I made my first batch of PC-Glycol about a year ago and it's still going strong. -- Rod Smith, http://www.rodsbooks.com Author of books on Linux, FreeBSD, and networking |
#4
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Keeping qualities of low-sulfite, metol-based film developers
Rod Smith wrote:
In article om, "Brad Dow" writes: Is a certain concentration of sodium sulfite critical to the keeping qualities of developers that use metol as the only reducing agent? To put the question in context, consider a hydroquinone-free variation on DK-50: metol 6g sodium sulfite 30g sodium metaborate 10g postassium bromide 0.5g water to make 1 liter With the relatively low sulfite level of 3%, would such a developer be less stable in storage (in full glass or nalgene bottles) than D76H or D23, which call for 10% sodium sulfite? If so, what is the minimum level of sulfite required for good keeping qualities? I can't answer your question with respect to the developer you mention, but Patrick Gainer has created some interesting NO-sulfite developers with excellent keeping qualities. Most of Gainer's developers are phenidone/ascorbic acid (PC) developers, though. Specifically, PC-Glycol is made from phenidone and ascorbic acid in glycol with a separate solution of carbonate. (The two are mixed together at time of use.) PC-TEA consists of phenidone and ascorbic acid in triethanolamine (TEA), which acts as both a solvent and an activator. Check http://www.apug.org/forums/showthread.php?p=255352 for details. IIRC, metol is soluble in propylene glycol but not in TEA. Thus, you might be able to cross your DK-50 variant with PC-Glycol to get something similar to DK-50 with excellent keeping qualities. I made my first batch of PC-Glycol about a year ago and it's still going strong. Metol is the hydrosulfate of 4(methyl-aminophenol) or some such thing. The hydrosulfate is what makes it soluble in water. It is possible to remove the hydrosulfate, which is sulfuric acid, and dissolve the Metol base in TEA or glycol. This can lead to some interesting developers, including a metol-ascorbic acid stock solution in either TEA or glycol. It has more tanning ability than the phenidone version, which is supposed to give it more sharpness due to the refraction of the gelatin relief image. I'll dig up my notes and come back later with a recipe. It doesn't require much heating: just enough to reduce the viscosity for quicker mixing. Basically, the idea is to make a slurry with TEA, metol and ascorbic acid, then add just enough water to make the TEA basic. There may be a little precipitate of the sulfate, but it is possible to make quite a concentrated stock in this manner. |
#5
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Keeping qualities of low-sulfite, metol-based film developers
PATRICK GAINER wrote:
Rod Smith wrote: In article om, "Brad Dow" writes: Is a certain concentration of sodium sulfite critical to the keeping qualities of developers that use metol as the only reducing agent? To put the question in context, consider a hydroquinone-free variation on DK-50: metol 6g sodium sulfite 30g sodium metaborate 10g postassium bromide 0.5g water to make 1 liter With the relatively low sulfite level of 3%, would such a developer be less stable in storage (in full glass or nalgene bottles) than D76H or D23, which call for 10% sodium sulfite? If so, what is the minimum level of sulfite required for good keeping qualities? I can't answer your question with respect to the developer you mention, but Patrick Gainer has created some interesting NO-sulfite developers with excellent keeping qualities. Most of Gainer's developers are phenidone/ascorbic acid (PC) developers, though. Specifically, PC-Glycol is made from phenidone and ascorbic acid in glycol with a separate solution of carbonate. (The two are mixed together at time of use.) PC-TEA consists of phenidone and ascorbic acid in triethanolamine (TEA), which acts as both a solvent and an activator. Check http://www.apug.org/forums/showthread.php?p=255352 for details. IIRC, metol is soluble in propylene glycol but not in TEA. Thus, you might be able to cross your DK-50 variant with PC-Glycol to get something similar to DK-50 with excellent keeping qualities. I made my first batch of PC-Glycol about a year ago and it's still going strong. Metol is the hydrosulfate of 4(methyl-aminophenol) or some such thing. The hydrosulfate is what makes it soluble in water. It is possible to remove the hydrosulfate, which is sulfuric acid, and dissolve the Metol base in TEA or glycol. This can lead to some interesting developers, including a metol-ascorbic acid stock solution in either TEA or glycol. It has more tanning ability than the phenidone version, which is supposed to give it more sharpness due to the refraction of the gelatin relief image. I'll dig up my notes and come back later with a recipe. It doesn't require much heating: just enough to reduce the viscosity for quicker mixing. Basically, the idea is to make a slurry with TEA, metol and ascorbic acid, then add just enough water to make the TEA basic. There may be a little precipitate of the sulfate, but it is possible to make quite a concentrated stock in this manner. I'm back. A solution of the metol base in glycol may be prepared as follows: Take 10 grams of metol and 9 grams of TEA (about 8 ml at room temp.) and make a paste. Add a teaspoon of hot water and keep on stirring. At this point, decide whether you want to use propylene glycol or TEA as the main solvent. I would suggest glycol as being the more flexible. Add enough to bring the volume to 100 ml. You may treat this solution as if it were 10% metol. You could use it to play with D-23 clones or whatever strikes your fancy. To make 500 ml of a stock of MC-Glycol: Take 5 grams of metol, 50 grams of ascorbic or erythorbic acid, and 85 ml of TEA and make a paste or slurry. Add 50 ml hot water and stir. Add glycol to make 500 ml and stir. It will help to heat while stirring, but temperature need not be any higher than you can get with a water bath or double boiler. You must have another stock of an alkali, or add some solid alkali to the working solution. I have used the metaborate B solution of PMK. Look up what others have been doing with PC-Glycol and try the same. |
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