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> Contamination of graduates |
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#1
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Contamination of graduates
Hello! I often read about contamination. I would like to know if it's necessary to keep separate graduates for various chemicals or whether a good soap washing will decontaminate a graduate? I think in the case of trays such cleansing cannot be assured due to the clear instructions to keep 3 different trays.
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#2
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I do keep separate measuring vessels for each of dev, stop and fix, but as the chemicals do not spend much time in there (and especially if you use glass) I don't see that it is 100% necessary. I have accumulated an assortment over the years and I guess having separate ones means you do not have to stop and washup in the middle of preparing working solutions.
Certainly you may want to keep developer utensils separate but no reason other than the extra faff not to use a single stop and fixer graduate. Colour has more chemical stages so may have different requirements but I don't do colour so can't suggest anything... |
#3
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Contamination
Most of the normal developing chemicals can be neutralised by filling them with something like Milton at 50% solution and leaving it for around 24 hours and rinsing out.
Hard plastics like ordinary clear Paterson measuring beakers are not so prone as vessels made from polypropylene. I measure my RA4 and C41 chemicals in Paterson beakers and only need just to rinse them out afterwards and so far have had no detrimental effect. As Bob has said glass measuring beakers and storage jars need only a rinse out with plain water. |
#4
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I have a couple of the Paterson cylinders, and use them for blackj and white, and just rinse them out with plain water between chemicals, seems to work fine
Richard
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jerseyinblackandwhite.blogspot.com |
#5
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Contamination
The main source of contamination applies when you are dealing with RA4, C41 and principally E6 colour chemicals. It is a long time since I have used E6 and in the last Tetenal E6 processing kit there was a written warning about using the same measuring beakers for the 1st developer, bleach and 2nd developer as there is a possibility of a 'carry over.'
When mixing the developer for RA4 and C41 if you rinse out the mixing beaker that has held one of the chemicals the first 3 or 4 rinses will be tinged slightly pink. This will carry over if not completely eliminated. |
#6
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Some do, I don't and never have as I use my measures in sequence and keep most chemicals like stop bath and fixer pre-mixed in bottles and pour straight from them into tanks or trays. Actually when I used replenished developer it was the same.
A good wash and re-use for anything. Never had an issue in 50+ years of B&W and Colour processing. Ian |
#7
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Over all of the decades that I have done film and print developing, I have never even thought about this subject - of using a separate graduates for individual chemicals, which for me is three, as I only do b/w.
I do use the same graduate when measuring out all three chemicals and just give it a good rinse between each of them. Over all the decades that I have done this, I have never had a problem but the chemicals are not in the graduate for very long, usually minutes at most. As for bottles for long term storage of liquids, I use a different labelled bottle for each and rinse them out well when a bottle is emptied and before refilling it again with a similar liquid. But be careful with your labeling and don't take one off before refilling with a similar liquid and writing a new label out. I took the label off of a bottle fix quite recently (see my post 'Is my metol dead') and accidentally refilled the bottle with developer, which then died on me by the time I went to develop my second film. So be warned, mistakes can and do happen. Terry S |
#8
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graduate materials
I note that some scientific and medical laboratories handling chemicals still use glass graduates but in general glass is regarded as hazardous and they substitute PP (polypropylene), virtually unbreakable, POM (polyoxymethylene) and PMP (polymethylpentene), both tough and resistant to high temperature. Some photographic chemicals stain PP, POM and PMP but this takes some time. Graduates used for proportioning concentrates are unlikely to be in contact with nasties for more than a few minutes, so all are quite safe. Paterson graduates are moulded of PS (polystyrene).
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#9
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Glass graduates
Quote:
I have 2 x 100ml graduates and 2 x 50ml and to be hones they are not brittle. They are made from Pyrex glass which is TOUGH. They have tipped over on the bench and at one time I dropped one into the sink. It literally just bounced! I also have a 500ml and 1000ml, again made from Pyrex and like the 50's and 100's they are certified accurate and trying them against one of the Paterson 2lt jugs, the jug is very definitely not accurate. the 2lt measuring bar is about 50cc over the stated quantity. That is another reason why I use glass out of preference |
#10
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Quote:
I use the 10/11 ml plastic graduates that came with Photocolor kits to measures my film developer or a syringe. Ian |
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