Hmmm... Unipure, Unilab, Univar, Labchem or Technical ?
Posted 30 May 2007 - 09:15 PM
I'm ordering some chemicals from a facility that isn't photography oriented like say the formulary or B&S ... It is however local and therefore cheaper and much easier to deal with.
They do offer all the chemicals I need but have them in a bewildering array of different forms and purities - the cost of the chemical sky rockets with the % purity of the chemical...
Purities are based on a different standards with the names:
Unipure, Unilab, Univar, Labchem and Technical (and some other odd ones chucked in)
each getting less and less pure as you go along - Unipure it seems is for mad scientists who need very quantitative results where the purity is near on %100 all the way down to Technical which lists purity at %60 in some cases ...
What sort of quality are photographers looking at when they soup up home-brew versions of Kodak developers and reversal bleach etc... ?
If I bought only Unipure I'd be looking at a $1000 per gallon of D19 (ok I made that figure up, but trust me it would be high)
If I bought Technical grade the cost might be about the same or less but would the quality/concentration be up to scratch ?
Specifically I need some potassium dichromate and some sodium sulfide (stink bombs) -
The sodium sulfide I have from B&S is in stinky flake form - the Technical stuff I can get locally at %60 is also in flake form the other more expensive 'uni...' forms are crystals - so I'm guessing the B&S sodium sulfide I have here (running out fast) is Technical grade ?
The B&S pot dichromate is just orange crystals - no idea on its purity
here is the site if anyone in NZ is interested: www.ajaxfinechem.co.nz
Any pointers in which grade I should be going for ? no use in getting something so pure and costly if it the same purity is redundant for whatever other reason huh...
any help appreciated,
Posted 31 May 2007 - 01:03 AM
Edited by David A Venhaus, 31 May 2007 - 01:06 AM.
Posted 31 May 2007 - 03:44 PM
ISO (International Standards Organization) has set standards for chemicals to be considered photographic grade quality. Photographic grade is different then regular grading, certain small impurities can make a big different such as metals like iron in the developer. I am not familiar with NZ standards but for important work, make sure that whatever chemical you buy meets the ISO standard.
Yes, "Photographic Grade" is the most appropriate guide.
Posted 01 June 2007 - 03:46 AM
I'll take a look at the ISO stuff once I get back from holiday... off to murder some fish for the long weekend with spears, snorkels, beers and wotnot - big debate going on in my head is 'do I really want to take my underwater housing and 16mm for some practice?' or just go and have a relaxing time for a change - might just take the medium format instead, its only 2kg....