gaslight (was Instructors & Formaldehyde

Terry King (101522.2625@CompuServe.COM)
03 Jul 96 16:51:29 EDT

Judy

I thought that we had finished this.

>For "consistency of results," you can't, I repeat -- can't -- just size
>"somewhere along the line." For consistency of results, you would have to
>size at exactly the same point along the line -- and in the same manner.

You size when you need to for the paper concerned. You said that some papers
will accept a couple of coats without sizing. Trams are utilitarian Judy but not
very exciting. If you want to size that way I have no objection but that does
not mean that everybody else has to.

>> Hamlet, Act One, Scene One,Line One ! ! !

>Perhaps. I'll look it up.

It says 'For this relief much thanks.'

I should be so lucky.

> But, more to the point am I *now* to understand that ossein as paper size
requires a hardening coat of
>dichromate?

Judy, my usual practice, if I am not using a gesso or gloy substrate, is not to
apply a first size, but to size between coats. To do this I use a 3 % ossein
size of which I have a large sack bought on behalf of students. I do not harden
these coats in any way. The papers I use for this method are Fabriano 5 and
Bockingford. I have tried the gelatine substrate method using a hardener
following comments from yourself and Dick Sullivan because I needed to be
flexible in my approach, but I preferred the three methods of , here come the
funny names, pterotype, acrylochrome and my standard sizing method. To sum up
I do not use gelatine or ossein as a first coat. I do not harden the gelatine or
ossein with glyoxal, formaldehyde or dichromate but if the ossein is dichromated
it clears. I do not regard myself as being an 'authority' on the subject.. I am
not even sure that there shold be an authority.

I hope that this clarifies things because I did not understand the next bit.

> Does or doesn't a coat of ossein at any stage in the printing process require
a hardening coat of dichromate?

I do not do so. But the ossein can be hardened with dichromate instead of
glyoxal or formaldehyde as a substrate.

> Always? Sometimes?

Both ! Depends on the method and paper you are using.

> If sometimes, when? If it does, what is advantage over Knox hardened with
glyoxal, other than not being available at corner supermarket?

I cannot remember how we got into this.

I first used ossein as the gelatine to use in making oil pigment prints, where
it does a better job than corner store gelatine, where I use chrome alum as a
hardener.. I then found that it works well as the size in platinum/palladium
printing because it is pure. Platinum, according to experienced authorities,
reacts badly with gelatine but it does not seem to do so with ossein probably
because it is deionised. It also works well as the size for other 'solution'
processes. It also works well as the gelatine in making carbon tissue where
before I had been using fancy expensive leaf gelatine on the recommendation of a
very famous and valuable book. As it works for everything else, I use ossein as
a size in gum printing as I have lots of it, it works and costs no more than the
stuff from the corner store which has now returned to the kitchen.

I do not use ossein for substrates hardened with dichromate, glyoxal or
formaldehyde. If I am to use a substrate I use an acrylic gesso or Gloy or, with
appropriate papers, none at all.

I did harden ossein with dichromate once and it cleared after a short wash.

I do not hold shares in Croda who are a UK eqivalent of Aldrich, informative and
helpful.

I have passed my experience on to the list as a contribution to the common
knowledge.

I do not say that people have to follow my example.

The methods are there for people to try for themselves so that they can
establish their own methods suiting their own conditions and objectives.

Here I think is an appropriate place for the recessional.

For ever and ever

AMEN

Terry