Re: SLIDE STORAGE - LAST WORD ON,

[P3D Gregory J. Wageman <gjw@xxxxxxxxxx>]

Mike K. writes:

>So it's a good idea for the product to say what it's made of, and to know
>that it's safe.  It's your slides, protect them.

>Of course, they may just label the product with a material name that 
>customers just like to see..... so making sure the mfgr is a reputable
>one might be a good idea as well.

One good way is know how to read the recycling codes.  These aren't yet
on all plastics, but they are on many.

LDPE - Low density polyethylene (safe, but may contain slip agents)
HDPE - High density polyethylene (safe)
PP   - polypropylene (cast: safe, extruded: may contain slip agents)
V    - vinyl (definitely unsafe)
PS   - polystyrene (unsafe)
PETE - polyethylene terephthalate (safe)

Mylar (polyester) is the most stable of all plastics.  If it has a code,
though, I'm not aware of it.

Acetate and PVC are not archival plastics.  PVC can decay to hydrochloric
acid!

>P.S. - Seems like a Stereo-slide Baja case from the 50's would have 
>       outgassed all it's going to outgas by now.  How long will 
>       significant outgassing continue?

I think it varies with the material.  With PVC, at least, it continues
for the life of the material.  It depends on whether the harmful component
is a basic ingredient of the material (as with PVC), or an additive
(like slip agents, which are added during the forming process).

	-Greg


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