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Hmmm... Unipure, Unilab, Univar, Labchem or Technical ?


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#1 Nick Mulder

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Posted 30 May 2007 - 09:15 PM

Hello,

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,
Nick
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#2 David Venhaus

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Posted 31 May 2007 - 01:03 AM

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.

Edited by David A Venhaus, 31 May 2007 - 01:06 AM.

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#3 John Pytlak RIP

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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.
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#4 Nick Mulder

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Posted 01 June 2007 - 03:46 AM

So as I understand it Unipure, Unilab, Univar, Labchem or Technical are redundant standards as photographic grade has extra specifications on particular unpurities ...

okidoki!

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....
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