Re: polivinyl alcohol vs. gelatin sizing

Thanks Ryuji.

Your explanation seems very complete, it just doesn't match what Kevin
Sullivan told me and I am trying to talk to him (I will email as soon as I
receive his opinion).

You said that the PVA needs to be mixed with gelatin (gum?) for the sizing,
Kevin said that it does a perfect and complete sizing by itself (no gelatin,
no preservative, no hardener).

I am assuming that after you size your paper is when you apply the sensitive
stuff whatever it is (and Kevin uses platinum/palladium).

Somewhere it seems to me to understand that it can be applied on the gum
bichromate process instead of the arabic gum and this is new to me.

In theory PVA is transparent* (just dried or semidried) and should work
better than the arabic gum and if it is not very hard it shoul dissolve in
water leaving only the color portion hardened by the bichromate.

Are we in the same track? Is this correct? Has anybody tried this?

Thanks

Giovanni
* Alcohol version is more transparent than the acetate version.

pd1 I only have used for sizing and works in my case, in my paper, at my
temperature (very hot in Rome-Italy right now)

pd2 This bunch of alternative processes we are trying are not "pure 1850
processes" since we are all digital, right? What's wrong using a better
chemical that did not exist that time?

----- Original Message -----
From: "Ryuji Suzuki" <rs@silvergrain.org>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Saturday, July 30, 2005 4:58 PM
Subject: Re: polivinyl alcohol vs. gelatin sizing

> From: Giovanni Di Mase <gdimase@hotmail.com>
> Subject: Re: polivinyl alcohol vs. gelatin sizing
> Date: Sat, 30 Jul 2005 16:28:30 -0400
>
> > Let's be very clear, which one is Elmer's glue made from?
>
> The main ingredient is poly(vinyl acetate) and water.
>
> > When you said PVA is acetate or alcohol?
>
> PVA is an ambiguous acronym. Some people use PVOH to indicate
> poly(vinyl alcohol) to avoid confusion.
>
> > Yes, there is a confusion between them.
>
> There is no confusion in terms of chemistry. The confusion is just in
> acronyms. It's also that vinyl acetate and vinyl alcohol are often
> used as copolymers and also as mixtures of multiple copolymers in
> practice to achieve desired properties. One example I gave was acrylic
> medium.
>
Received on Sun Jul 31 05:17:49 2005