> > The tests WITHOUT Tween 20 coated smoothly and without problems, in fact
> > the results are no different from any of the prints that I've made in
> > the past on supposedly "good" batches.
> >
> > The ones WITH Tween 20 just sank right in before I had time to spread
> > the sensitiser, as I've always found to be the case. They weren't
> > difficult to clear but did show mottling, but I think that this is a
> > problem with the Tween/Platine combination rather than this particular
> > batch.
>
> There may be a problem in the way that you use Tween with Platine, but I
> use it in every one of my prints and it works great. And if there was a
> problem I would certainly know because most of my images have large
> expanses of smooth skies, water and tonal gradients which are the toughest
> test of all.
>
> I double-coat my Platine. In the first coat I use Tween. In the second
> coat I substitute glycerine for the Tween. Works like a champ.
>
> David Fokos
I am coating approximately 240 sq. inches. For this I use:
1st coat
3.2 ml. ferric oxalate solution
2.4 ml. standard palladium solution
4 drops standard platinum solution
4 drops 10% Tween 20
I brush this fairly wet coat onto the paper with a 4" wide foam brush. It
is vitally important that this solution be mixed well. If there is a
concentrated area of Tween in the solution or perhaps on the edge of the
mixing glass, this can get onto the paper and it will immediately soak
through to the other side in a tiny spot. I smooth the coating out and
then a pick up the paper by one corner and use a quick up & down jerking
motion to get the sensitizer to run a bit. I then grab another corner of
the paper and do the same. Then I hang it by a corner for about 5 minutes
and then put it into a drying cabinet (horizontally). I dry the paper
until it is dry to the touch but still slightly cool on the backside. I
then apply the second coat.
2nd coat
4.0 ml. ferric oxalate solution
3.0 ml. standard palladium solution
5 drops standard platinum solution
2 drops of glycerine
Using a different brush, I then brush this onto the paper quickly. It's
important to get it spread around quickly because once it starts getting
absorbed into the paper you won't be able to spread it as easily. I
continue smoothing out this coating until the brush is almost dry. At
this point the paper will have a dull sheen. I hang the paper until it
has a matte finish (about 5 minutes). Then it goes into the print dryer
until dry to the touch but still ever so slightly cool on the backside
(you just want to have a little residual moisture left in the paper).
Print and develop in hot potassium oxalate, clear in Kodak Hypo Clearing
Agent.
To actually answer your question, I use the Tween to allow the first coat
to sink in a little, and the glycerine to keep the second coat on the
surface more. I don't think I would want to do it the other way around
because then you would be trying to "pass one coating through the other
-- sort of".
David Fokos