From: Jeffrey D. Mathias (jeffrey.d.mathias@worldnet.att.net)
Date: 11/06/00-06:27:29 AM Z
Mark Nowaczynski wrote:
> .... My lab is temperature
> and humidity controlled (always 50-55% RH) and therefore the environment
> is ideal and consistent year round.
> ...
50-55% RH is acceptable, but hardly ideal. For Crane's paper (AKA
"cover-90"), I find a RH of below 40% a bit superior.
Also, and more critical, is that the ambient temperature while coating
should be below 70F (for traditional DOP). But as Craig Koshyk pointed
out the coating solutions may need to be warmed. Specifically the metal
solutions, and perhaps more than a "wee bit" above room temperature.
They should be heated to that temperature which will keep all the
material in solution (this will depend on the solution strengths).
Place solution bottles in a ceramic cup, fill cup with distilled water
to just below the caps of the bottles, cup goes on warmer. A coffee
warmer should work fine, heat to warm, but not too hot to touch. Note:
if you use a stainless roll film can, likely holes will be produced in
the bottom of the can eventually leaking the water into your coffee
warmer and sending you to purchase a new one (from experience).
Coatings made above 40%RH and 70F may produce random problems, something
to remember when problem solving. This is not to say that coatings
cannot be made above these parameters, only that there is a greater
element of chance that something may go awry as one goes further beyond
theses conditions. For POP with AFO sensitizer and lithium palladium
salt, conditions are typically below 70%RH and 70F to maintain
consistancy.
I have experienced the same things with Platine as Carl Weese mentioned
in his post. Each paper (as well as process variations) may have
different optimum conditions and limitations. This is important to
consider when a new paper is tried.
> ... Apparently he pre-washes
> Arches Platine in water, dries it and then coats it etc.
>
> I have tried this with great results ...
Thanks for the new and interesting info. It may be that the wash
removes some of the sizing or redistributes it more evenly which could
be consistent with Carl's heavy working of the coating into the paper.
-- Jeffrey D. Mathias http://home.att.net/~jeffrey.d.mathias/
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