RE: report on glyoxal yellowing

Judy,

I thought I would submit the results of my informal yellowing tests of Rives
BFK.

In my test I preshrunk, and then sized in Knox gelatin, 28g per liter,
squeegeed excess gelatin and hung to dry. This was followed with a glyoxal
hardening treatment, 15ml 40% glyoxal per liter with a tablespoon of baking
soda for 5 minutes with light agitation and inter-leaving. That step was
followed by a 5 minute tap water soak. Then hung to dry.

>From this batch 6-4x4 inch samples were cut from a single sheet of paper, 3
pairs. Of each pair one swatch was sealed in a zip lock bag and 1 was left
exposed to open air.

1 pair was stored in complete darkness, 1 pair was taped to a Northward
facing window inside my home and the last pair was taped to a shaded Western
facing window outside. The test began in mid August.

As of tonight I can observe no yellowing when compared to each other and to
an untreated BFK parent sheet stored in my flat file cabinet.

I did see extreme yellowing though where the gelatin pooled at an edge or
corner while drying. But these amounted to only trace amounts.

Tomorrow given time I will measure each swatch with a densitometer and check
what the machine sees.

My 2 cents,

Don Bryant
Received on Thu Nov 11 21:00:54 2004