RE: Sizing paper with gum and dichromate

Hi Loris, I routinely use gelatine and formalin, batch processing paper in a
bath. I use one coat of unhardened gelatine, leave it to air dry overnight,
then reheat the gelatine the next day, add the formalin to the bath and do
the second dip. After that I discard the whole bath. As I use grocery store
gelatin, I don't find this a huge expense, and as I keep my baths quite
shallow, I usually don't have enough gelatin left at the end to be useful
anyway. As to keeping the solution workable, I store the gelatin solution in
the refrigerator in between times and reactivate it in a warm water bath.
Stored at room temperature, it decomposes very rapidly. When I am coating, I
sit my tray of solution in a tray of 50 degrees C hot water to keep it nice
and workable. This usually stays warm enough to coat 16-24 1/4 sheets of
watercolour paper without changing the water bath.
It's important to flush the gelatin solution down the drain with plenty of
hot water, to avoid it setting in the pipes. If you're using a brush, like
Christina, it's really important, as she says, to wash the brush out, for
the same reason.

For brush coating, set the gelatin/formalin solution in a tray of hot water
- it will remain workable for quite a while (at least 1/2 hour) as long as
it stays warm.

Hope this is helpful.
Kate

-----Original Message-----
From: Loris Medici [mailto:loris.medici@altinyildiz.com.tr]
Sent: Tuesday, 27 December 2005 9:23 p.m.
To: alt-photo-process-l@sask.usask.ca
Subject: RE: Sizing paper with gum and dichromate

Thanks Christina. How much time the solution continues to work without
problems? (Like becoming messy and unapplicable...)

TIA,
Loris.

-----Original Message-----
From: Christina Z. Anderson [mailto:zphoto@montana.net]
Sent: 26 Aralık 2005 Pazartesi 16:52
To: alt-photo-process-l@sask.usask.ca
Subject: Re: Sizing paper with gum and dichromate

Hi Loris,
I use a 3% gelatin solution, which is probably 2.8% because I use 4 packets
of 7g each Knox gelatin in a liter of water. Then when that is prepared
(boiled or just heated, depending on whether you forget it on the stove or
not) add 20ml formaldehyde to the mix and brush on. Use right away and toss
what you don't. Rinse brush immediately after use, too.

I have not used formaldehyde for 7 years...
Chris
----- Original Message -----
From: "Loris Medici" <loris.medici@altinyildiz.com.tr>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Monday, December 26, 2005 4:41 AM
Subject: RE: Sizing paper with gum and dichromate

>
> Hi Christina,
> What is the percentage of your gelatine size solution and how much
> formaldehyde do you add to it?
>
> I know you're currently using glutaraldehyde as hardener but, what was
> your procedure when you were sizing with combined gelatine /
> formaldehyde?
>
> I plan to use 6% gelatine solution and a separate hardening bath. If
> it can be made without having a messy & hard to coat gelatine
> solution, I would like to learn the way of sizing the paper with
> gelatine + formaldehyde in one step.
>
> TIA,
> Loris.

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