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[GreenYes] Re: Green Darkroom Parties


Title: [GreenYes] Re: Green Darkroom Parties

From: "Nancy Poh" <greenbeingnancy@no.address>
Subject: Re: Green Darkroom Parties (was [P2] Green cleaning parties)
Date: Mon, 30 Jun 2008 15:46:05 +0800

> I think I found storage ware for your chemicals.

Well, storing in my darkroom is not a problem. Finding
suitable bottles to package my products is.

The reason is that, I can use glass for sensitive solutions,
and glass has zero gas permeability. I can also reuse PET
bottles from water, beverages, etc. But these are not viable
options to package products.

Most darkroom workers have no need to go to a store to buy
Rubbermaid products just for darkroom use. I think most
Rubbermaid products are HDPE or LDPE anyway, and they are fine
for their intended use, but not photographic developers. Pick
up a PET bottle from a recycle bin and wash it. Better
material for gas permeability and better for the environment.

> The following comes from the usenet form rec.photo.darkroom (
> http://www.photodigital.net/lists/rec.photo.darkroom/subject.html):
>
> I found a table of O2 permeability of various packaging films for food
> storage. There are similar results, plus some additional materials. They are
> in the same units shown above:
>
> ======================================================================
>
> Low Density Polyethylene (LDPE): 510 (food wrap, grocery bags) Orientated
> Polystyrene (OPS): 355 (Styrofoam) Polycarbonate (PC): 300 (eg Lexan) High
> Density Polyethylene (HDPE): 185 (Milk, juice jugs) Oreintated Polypropylene
> (OPP): 160 (Margarine tubs) Polyvinylchloride (PVC): 8 (Cleanser bottles)
> Polyethylene Terephthalate (PET): 6 (Soft drink bottles) Polyvinyldichloride
> (PVdC): 0.6 (Saran wrap) Ethylene Vinyl alcohol copolymer (EVAC): 0.1
> (interior coatings, gasoline containers)

As you see, there is a good reason why PET and PVC are better
than HDPE, which is much more common material.  Since PET
bottles are not widely available as stock items (see my second
post), many smaller businesses may be forced to use PVC (much
more available than PET as stock bottles).

I have been advocating PET bottles for photographic developers
for many years, since long before I even had my first product
on the drawing board.

http://silvergrain.org/Photo-Tech/plastic.html

This page is scheduled to be revised and moved to my new site,
so please don't make a link... yet.

--
Ryuji Suzuki


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