Friday, April 2, 2010

Photo Engineer's succinct 2008 post, with comments

Photo Engineer
06-16-2008, 07:45 PM
I did not see this post when it went up over a month ago. I was in Montana at the Formulary.

I can say that Kodak did develop some products for Polaroid, because even though Land was a genius at inventing, his engineers did not have production coating machines nor did they have emulsion formulas and so Kodak developed a series of products for him including some B&W and color products. I do not know which ones.

The pod contains either KOH or NaOH as alkali along with restrainer and carboxymethyl cellulose (Unflavored Citrucel to US people :D ). There are also some developers and silver halide solvents. The film sheet is a film sheet but the reciever sheet is a special thing which forms the positive print. The whole thing is like a monobath.
Bob says: Yes almost, it is KOH and/or  LiOH, sodium sulfite, developer and cellulose - as stated, and not difficult.
The receiver sheet is indeed a special thing - that we need to figure out still.  That receiver is the key to controlling the DTR rate and producing the fine negatives we want.

In addition, the package contains rails to keep the distribution of pod goo even over the width and length of film, and the pod has dividers to promote even spread and burst when pressure is applied.
Comment: Very important but doable geometry in my view. Polaroid did the hard part with the roller designs. Also we do not necessarily have to use burst and spread.

Filling a pod is a very exact and complex process and assmbling a pack is very expensive with some rather complex equipment involved.
Comment: Probably the most expensive part of any product is the assembly and packaging of the components.  However, the equipment does not have to be very complex, and I think even Polaroid did some hand loading of the film.

Hope this helps.
Sure does

PE

from the 55 pod MSDS

POTASSIUM HYDROXIDE 1-5 001310-58-3
LITHIUM HYDROXIDE MONOHYDRATE 1-5 001310-65-2
T-BUTYLHYDROQUINONE 1-5 001948-33-0
SODIUM SULFITE ANHYDROUS 1-5 007757-83-7
SODIUM THIOSULFATE PENTAHYDRATE 5-10 010102-17-7

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