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 D94 (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

 

[Maris]

I used to sell Ajax laboratory chemicals in Australia and sure enough some stock (paid for, naturally) got diverted to personal photographic purposes.

In every case I would go for the lowest grade available, Technical if possible or Labchem or Unilab as a grudging alternative. I never encountered a problem. High purity analytical grades are not required for ordinary photographic work and they cost a bomb.

Since I have been out of the business a long time I'll tell you a trade secret. Quite often the Technical grade and the Analytical grade are one and the same if the source material is good. The analytical grade is however exactingly assayed and packaged so that the list of impurities (miniscule) on the label is reliable.

 

[Roger Hicks]

Dear Nick,

The previous poster knows a lot more than I, but even so, here are a couple of extra throughts.

In the days when I used to do this, I was governed more by minimum quantity available than grade -- sometimes Tech or even Lab were only available in such huge minimum quantities that I'd go for the next up, occasionally even Analar.

Most photo-chemistry can be synthesized at home, with HUGE levels of impurity, and still work, so Tech is fine. The impurities that make big differences in small quantities -- tin salts, for example -- are unlikely in the extreme to be present.

Cheers,

R.

 

[nick mulder]

cool - thanks for the info... I'll go with cheap I wasn't so worried about the concentration issue as that can be worked around - more concerned about what say if you had %60 concentration what the other %40 was composed of ...

Belly button lint ?

Anyway - I wont break the bank with the technical grade as I can get reasonably small amounts in one pop - 500g as opposed to 5 Kg for example

 

[nick mulder]

Nick: are you goin' to make b&w slides?

Kinda - 16mm reversal developing, so I can project straight from the film that was in camera (tests, fun etc...)

Same thing in terms of processing yes (aside from the funky tanks) - I have done some in 4x5 but the results weren't as spectacular as I'm getting with the proper reversal 7276 plus-X film and 7374 Television Recording Film I have here in 16mm ...

Have you tried it ? Its a pretty neat process to add to anyones list of 'been there done thats'