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#51
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Rodinal
Dan Quinn wrote: John wrote I believe the original formula was published around 1905 Water @ 125F 750ml p-Aminophenol Hydrochloride 100g Pot. metabisulfite 300g Water to make 1.0L 50% Hydroxide Solution Water @ 65F 75ml Sod. Hydroxide 50 Water to make 100ml From my site of course ;) Nice site but where are the galleries? One other formula of a Rodinal type has been posted this thread. Perhaps you saw it: 20gr p-AM, 60gr metabisufite, and 28gr KOH per 400ml. A complete discription of it's compounding is included. Contrast that mix with Formulary's 50gr, 150gr, and 215gr per 1000ml. On a liter basis the above posted formula has 70gr of KOH. Where does the Formulary and Jacks Pic come up with 215gr? Am I over-looking something somewhere? I've not done the arithmatic yet but would not be surprised if the 70gr gives the 3% KOH Agfa claims on their bottle. Dan Dan, The standard abbreviation for grams is "g". The abbreviation "gr" stands for grains. I'm sure you meant grams. Some Englishman might not be sure. I have used the Formulary kit. When you mix that, you do not necessarily use all of the KOH. You are instructed to add it little by little until only a few crystals are left. If you are dealing with USP chemicals, perhaps you can specify exact amounts of each chemical that will leave a few crystals. Photography does not, as a rule, need nor even profit from the use of USP chemicals, or scales that weigh to the milligram, either. If you can do what amounts to titration until an observable reaction happens, there are lots of uncertainties you can work around. Anything I say here is my opinion. I don't have the fear of failure that some others do, but my experience has been that as many failures happen when I follow to the letter another's instructions as when I use my teaspoons and "salt to taste". I'm preaching anyway, aren't I. |
#52
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Rodinal
John wrote
I believe the original formula was published around 1905 Water @ 125F 750ml p-Aminophenol Hydrochloride 100g Pot. metabisulfite 300g Water to make 1.0L 50% Hydroxide Solution Water @ 65F 75ml Sod. Hydroxide 50 Water to make 100ml That sodium 50g/40 ratio is close to the potassium 70g/56 I mentioned in my last post. The 40 and 56 are the gram formula weights. Yet the formula above has twice the p-AP and 85g more K. metabisulfite of any formula yet encountered for a Rodinal type developer. So the above formula has, by comparison , very little Na or K OH. Also the above formula does not maintain the same ratio of other Rodinal types when p-AP and metabisulfite are compared. All that acid and so little OH. I doubt the above formula will work. BTW, another p-AP product on the market is Calbe R-09. Dan |
#53
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Rodinal
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#55
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Rodinal
"Hektor Gonzal" wrote in message ... Hi all, I do not develop not more than 1-2 rolls of film in a week, shelf life is important to me. I don't use a lot of it, but my bottle I dated 24/12/01 on opening is still fine, although alomst empty. I have another question. I use 300 ml of working solution to develop 35 mm. films. the 1+50 dilution requires really little amounts of stock developer. Is there a threshold for the stock amount to be used, any minumum limits? Numbers get bandied around, official and unoffical. I personally use Rodinal 1:100 so use 3ml in 300ml for 35mm. 5ml in 500ml for MF. I have played around with 1:400 (0.75ml in 300ml) for stand development (which worked) Cheers, Nige |
#56
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Permeability of plastic?
On 3/25/2004 11:33 AM John spake thus:
On Wed, 24 Mar 2004 09:08:12 -0600, (jjs) wrote: Thanks for that, and your other post, Dan. I had an awful time finding small glass bottles. Even the pharamcists quit using them. So I ordered from Boston Round and by your post it appears that I guessed well. Why not just use the 250~300 ml plastic cough syrup bottles that any pharmacy has ? I believe that most are made of PET which is an excellent storage medium. Now's as good a time as any to bring up this sticky question: just how permeable *are* plastic bottles, anyway? I hear it said, over and over again like a mantra, that plastic bottles are no good because they let oxygen through. But is this really true? And is it true for *all* plastics? I suspect not, but can't say for sure since I'm not a plastics expert. What is the permeability of various plastics? PET? HDPE? others? Anyone know for sure? -- .... but never have I encountered a guy who could not be bothered to make his own case on his own show. - Eric Alterman on his appearance on Dennis Miller's bomb of a show on CNBC (3/17/04) |
#57
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Permeability of plastic?
Check out Ryuji's site:
http://silvergrain.org/Photo-Tech/ch...misnomers.html He is a chemist. _________________ Ready, Fire, AIM. Bruce Brooklyn, N.Y. |
#58
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Permeability of plastic?
On 3/27/2004 12:12 PM Bruce spake thus:
Check out Ryuji's site: http://silvergrain.org/Photo-Tech/ch...misnomers.html He is a chemist. Thanks. From his page on plastic bottles (http://silvergrain.org/Photo-Tech/plastic.html): Why manufacturers and chemists recommend glass bottles for storing photographic chemicals has a lot to do with idiot-proof factors. With a little attention, inexpensive and convenient plastic bottles can be used for most photographic chemical storage without compromising their shelf life. Plastic materials and chemical properties material gas permeability acid resistance max usable temp --------------------------------------------------------------- PET (PETE) very good reasonable 60°C HDPE poor good 120°C PVC very good reasonable 70°C LDPE very poor good 80°C PVdc (Saran wrap) excellent reasonable 65°C PET (polyethylene terephthalate) is used as a clear (colorless or tinted) bottle material in bottled water products. It has very small permeability to oxygen and nitrogen. Use PET for developers. Use PET or HDPE for most other chemicals. If you store acetic acid stop bath in concentrated form, use HDPE. If PVC coated cap is available, use it by all means. My bottles of D-76, Microphen, and various other experimental formula are still alive and as vigorous in filled and tightly capped 500ml PET bottles after two years! So take that, ye who say that only glass can be used to store photo chemicals! -- .... but never have I encountered a guy who could not be bothered to make his own case on his own show. - Eric Alterman on his appearance on Dennis Miller's bomb of a show on CNBC (3/17/04) |
#59
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Rodinal
John wrote
Am I over-looking something somewhere? I've not done the arithmatic yet but would not be surprised if the 70gr gives the 3% KOH Agfa claims on their bottle. Dan 70gr is quite a bit of KOH. Also aren't their bottles 500 ml ? I've read Dr. M. Gudzinowicz lengthy post where-in he compares one of your concoctions with Rodinal. In his conclusion he makes the observation that the new Rodinal has no "sludge". Although he is unclear I believe he is saying that the ph has been uped. I think that may account for the 3% KOH. That is only .3g/liter at 1:100 or .005 molar. He is not happy with that. How much that raises the ph I could'nt say. Metol, p-AP, and Glycin now make-up my list of developing agents which will do it all, film/print, acting individualy. My minimalist approach may be rewarding. Dan |
#60
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Permeability of plastic?
David Nebenzahl wrote
Why manufacturers and chemists recommend glass bottles for storing photographic chemicals has a lot to do with idiot-proof factors. With a little attention, inexpensive and convenient plastic bottles can be used for most photographic chemical storage without compromising their shelf life. Plastic materials and chemical properties material gas permeability acid resistance max usable temp --------------------------------------------------------------- PET (PETE) very good reasonable 60°C HDPE poor good 120°C PVC very good reasonable 70°C LDPE very poor good 80°C PVdc (Saran wrap) excellent reasonable 65°C Glass excellent excellent way up there So take that, ye who say that only glass can be used to store photo chemicals! I added a line. I hope you don't mind. What ever is used be sure the caps are of the Polycone/Polyseal type. Dan |
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