Digital BW, The Print

----- Original Message ----- 
From: "Loris Medici" <lorism@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Wednesday, August 27, 2003 8:25 AM
Subject: RE: [Digital BW] Re: Septone system (LONG)


> Hi Martin,
>
> > -----Original Message-----
> > From: Martin Wesley [mailto:mwesley250@...]
> > Sent: Wednesday, August 27, 2003 8:07 AM
> > To: DigitalBlackandWhiteThePrint@yahoogroups.com
> > Subject: RE: [Digital BW] Re: Septone system (LONG)
>
> > I always thought that the gelatin would be the weak link in
> > silver printing since it is an organic substance produced
> > from meat processing by products. Isn't it even less stable
> > than the paper? I know it is very hydroscopic and gas
> > permeable. Of course I suspect most quality inkjet papers are
> > size with gelatin so we may be in the same boat.<G>
>
> I think most of the modern inkjet and water color papers are
sized using
> a synthetic material named "Aquapel", not gelatine (even if
they use the
> term "gelatine sized").
>
> Regards,
> Loris.


Loris, that is a water repellent, if used it will be just part of
the total size. It is used for the same reason in concrete.
Instead of gelatine most papers are sized with PVA nowaday, it is
a synthetic gelatine that can have different grades of
hydrolisation that translate to different grades of hygroscopy
when dry.

Both gelatine and PVA in the digital papers may suffer of fungi
growth in the future, there are no silver or other heavy metal
traces left like in analoge processes to slow the growth and the
gelatine isn't hardened by other chemicals either. Hardening may
have negative effects that the layer will crack faster but on the
other hand it makes that layer less hygroscopic and by that less
prone to any organism growth. If the ultimate in archivability is
needed (especially outside archives) a fungicide may be a better
answer than hardening the gelatine size and coating. Of course a
coating that seals the image side will also help in that aspect.
However there's still no answer on how good the bond of inkjet
coatings is and how extra protection coatings affect that bond,
could be better or worse on the long run.

Ernst