You may be right, Kallitypes may coat differently than pt and pd. I haven't done but a few Kallitypes in years and have just started experimenting again.
>I've noticed in cyanotype, BTW (haven't made these tests in other media),
>that, as I have mentioned, with some papers double coating increases
>D-max, with others it decreases, wiping off emulsion.
Of course, this will vary from process to process and individual practices. If you are getting a glaze, then double coating may just wash off the first coat. I've had very little luck coating Martin's Platine in Ziatype, but I went back and tried my Tween 20 wet-soak routine and it worked like a charm. Martin is experimenting with Tween 20 and hopes he can find a better coating system for the Platine paper with traditional platinum.
>Sorry, I don't get that -- you mean that a shadow area can become
>completely white from self-masking? I've never seen that.
No. Because of the masking, the depth of the color in the final print is thin, therefore if any wash-off occurs, the paper base will show through. I believe that when coating glazing occurs, it is not even, but forms little hillocks. If you have ever seen a gum print being made, you will notice that after you stop coating, it is smooth and then as it sits for a second or twoo, the coating pools around the more upstanding fibers leaving darker round spots. I think they can occur in other processes but you can't see them because the emulsion is light colored.Glaze is no problem with gum in that it is a process where you want a glaze coat.
>I've never seen solarizing in platinum, but I have seen it in cyanotype,
>where it doesn't at all become paper white, but a lighter blue. Are you
>sure that paper white you notice is solarizing? Have you seen solarizing
>to paper white in other parts of the print? As noted, I never have, tho
>it sounds great.
Soarization is not a problem in platinum or a 25% or higher platinum mix in palladium, but pure palladium will solarize like the dickens. It's one of the main reasons that most printers use some pt in their mix. Although some printers make the perfect negative, those who are mere mortals like myself need some help. Some negatives might require more exposure to bring down the high values. This can be done sometimes by sacrificing some shadow values. If the material solarizes, then unless you are looking for a offbeat look, you are out of luck.
>
>However, I do have test prints in cyanotype on Rives BFK which show white
>lines something like you describe. I haven't looked at them under a
>magnifying glass, much less microscope. But since, as noted I've never
>seen solarizing to white with cyanotype, I've always assumed it was caused
>by fibres sitting on the surface, then washing off, leaving the area under
>them either uncoated or unexposed. Well, it really doesn't *look* much
>like that, but I couldn't think of any other explanation.
That very well may also happen, but I've noticed this is more of a problem when coating can solarize. Ziatype does not solarize, even with pure palladium and it tends to be exceptionally smooth. This is what got me thinking about these problems again.
I am in no ways positive about any of this. Mostly just theories that I thought I'd toss at the Group Mind of the List. None of the books on non-silver printing address these issues, which in fact, tend to be central to much of our craft.
Dick Sullivan
<center>Bostick & Sullivan
PO Box 16639, Santa Fe
NM 87506
505-474-0890 FAX 505-474-2857</center>
</x-rich>