From: Sandy King (sanking@clemson.edu)
Date: 12/10/01-01:48:49 AM Z
Judy Seigel wrote:
>
>He also says the potassium (colorless) alum keeps its hardening properties
>much better than chrome alum in solution, but gives no criteria for time
>or hardening properties in either entry.... which you do below. Thank you.
>Did you figure that out yourself or read it somewhere? If the latter,
>where?
Many of the older resource books on carbon recommend the use of
chrome alum for single transfer supports and potassium alum for
double transfer. I don't remember if any of these books actually says
that chrome alum hardens better than potassium alum but if one
actually works with the process in both ways this becomes immediately
apparent through the surface qualities of the papers one works with.
>
>PS.: wouldn't you accomplish the semi-hardening just as well by using a
>weaker solution?
Perhaps. Or perhaps the hardening is an all or nothing thing. In any
event the papers work as they should for my purpose with 2g per
1000ml of gelatin solution of either chrome or potassium alum, and
given that economy of usage I don't find much incentive to experiment.
Sandy
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