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

[Nick Mulder]

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

[David Venhaus]

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 May 31, 2007 by David A Venhaus

[John Pytlak RIP]

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.

[Nick Mulder]

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....