Re: Glutaraldehyde: a different kind of cautionary tale

But none of this, as far as I can tell in a quick glance, has any
relevance to gum.
kt

MARTINM wrote:
>
> "Do you think ..." hardening "means such different things?"
>
> To me "hardening" relates to a large variety of things:
> introducing particular chemical agents by means of a solvent (usually water)
> into gelatin. Dozens of such components exist - the patent literature is
> full of them. In addition
> hardening may also involve subjecting a dry gelatin layer to particular
> gases. Moreover there is heat treatment (which may not simply cover baking
> but also micro-wave exposure) to provoke strong crosslinking. Heated gelatin
> is said to form in situ aldehydes.
> Though producing similar effects as more conventional hardeners, I am not
> sure whether introducing monomers into a gelatin layer that are subsequently
> polymerized, may be regarded as hardening.
>
> It seems to me hardening involves the melting point of gelatin to be risen.
> However, this appears to be somewhat ambivalent since gelatin concentration
> is likely to have a large impact on gel strength.
>
> "... if it's not impervious to boiling water, then by what criterion is it
> considered to be hardened?"
>
> One criterion might be to what degree/at which temperature gelatin is
> swelling - that's to say, the quantity of water bound within the layer.
>
> Martin
>
> > Katharine Thayer wrote:
> > >
> > > MARTINM wrote:
> > > > " The more I hear about colloid hardening, the less I seem to know
> about it.
> > > > This might have to do with the vagueness of the term "hardening".
> > >
> > > Do you think it means such different things? In the leather industry,
> > > the test for knowing leather is "tanned" is whether it shrinks in
> > > boiling water. I *believe* that properly-hardened gelatin doesn't
> > > dissolve in boiling water (am I wrong about that?), and I know for a
> > > fact that properly-hardened gum doesn't dissolve in boiling water. So
> > > wouldn't being impervious to boiling water be a reasonable criterion for
> > > hardening?
> > >
> >
> > By my criterion above, I suppose glyoxal-hardened gelatin wouldn't
> > qualify, as it is said that it can be dissolved in boiling water. But
> > if it's not impervious to boiling water, then by what criterion is it
> > considered to be hardened? In which case you're right, the term is too
> > vague.
> > kt
Received on Thu May 6 11:26:27 2004