[alt-photo] Re: red spots in pt/pd

[etienne garbaux]

Chris wrote:

>I can't imagine what "red" spots would look like in pt/pd, but maybe 
>the red is, in fact, an orangey color or something.

The "red" spots I've seen are reddish brown -- the color of rust 
(which is likely what they were).  Mostly, spots in Pt are black, 
sometimes with a tiny white ring around them.

>So if it is a paper issue only then no need to worry, especially if 
>no one has seen it since 1999!

I don't think the root causes of the problem have gone away (although 
one of the seemingly most affected papers is no longer 
produced).  ISTR "spot" discussions much more recently than that.  I 
think it is more that the universe of Pt printers on the list doesn't 
change much, and each of us found a workaround we can live with so 
there is not much need for further discussion.

As others have pointed out, the chemistry can also cause spots, 
generally when there are solids in the coating solution.  I think it 
can be stated as a general rule that one should avoid any 
photographic solution that has crystals, precipitates, or other 
solids in it (with the possible exception of the sand, twigs, insect 
parts, and other flotsam you often find in gum ;-)

Best regards,

etienne