-greg schmitz
> Glass Plate Cleaning Formula
>
> The formula is from an article by James Enyeart which appeared in a 70's
> edition of the SPE Journal. It was adapted from a similar formula published
> by Eugene Ostroff and used for cleaning Daguerreotypes. I assume that it will
> work on prints, but I have no experience with that application. Oh,
> this formula will destroy glass colloidion (wet plate) negatives, so
> be sure you know which is which before using it on a glass plate
> negative (colloidion emulsions are brown in color compared to a more
> neutral gray of gelatin emulsions).
>
> Distilled Water 500 ml
> Thiourea 50 grams
> Phosphoric Acid (85%) 10 ml
> (You can also add a small amount of wetting agent, such as photoflo,
> if you are cleaning negatives)
>
> 1. If there is surface dirt, you can clean it first with tap water and a
> dilute solution of Parsons Ammonia.
>
> 2. Place plate in a tray of the Thiourea solution and gently agitate
> (if emulsion is cracked or peeling, better to swab the solution on
> locally with cotton balls than immerse).
>
> 3. When silvering appears to have dissappeared, rinse in tap water for
> one minute.
>
> 4. Fix for one minute (I don't recall having any problems with rapid
> fix, but you might want to use a conventional, non-hardening fix to
> be on the safe side.)
>
> 5. Rinse again for one minute.
>
> 6. Use washing aid for 30 seconds
>
> 7. Rinse with tap water for 2-3 minutes (This is for a film emulsion, don't
> forget to wash longer if you are doing a print.)
>
> 8. Use photoflo and dry. If any silvering remains, you can repeat the process.
>
>
> Hope this helps,
> Carson Graves
> carson@ileaf.com
>
>
>
>
>===for PGP Key finger Greg Schmitz <gws1@cunix.cc.columbia.edu>===
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