Wayde Allen (wallen@boulder.nist.gov)
Wed, 03 Nov 1999 14:41:17 -0700 (MST)
On Wed, 3 Nov 1999 FotoDave@aol.com wrote:
> > The dry, or shall we more accurately say solid, gelatin film has reached
> > its state of maximum cross linking. Adding hardener at this stage isn't
> > really going to increase the number of cross links.
>
> Yes, but most of the harderners we talked about here is water based, be it
> formaldehyde, glyoxal, or alum. I might be wrong, but the way I understand it
> is when you use the harderner on the "dry" or solid gelatin, the unharden
> gelatin will swell again and absorb the harderner and then get hardened by
> it, so in that sense the harderner is not really acting on the "dry" gelatin.
Sure you have to get the hardener into the gelatin film somehow. I'm not
too sure what you are getting at with this? The water that penetrates the
gelatin film either breaks some of the existing bonds or it simply fills
some of the space in the existing protein matrix. We aren't typically
dissolving the gelatin film in large quantities of water or heating it
until it melts.
If you assume that the hardener only strengthens existing bonds, it seems
to me this is the same as working on the basically dry film. In this
case, if the water actually breaks a few bonds you decrease the number of
bonds that can be hardened.
The counter to my argument would be for the hardening compound to somehow
increase the available number of binding sites and increase the number of
crosslinkages. Does anyone know ... ?
- Wayde
(wallen@boulder.nist.gov)
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