Re: Pure Pt printing and solarazation

Breukel, C. (HKG) wrote:
> I recently entered the world of pure Pt printing..(caveat: I "made"
> my own K2PtCl4, which is AFAIK quite pure, but I am not 100% sure
> about it, do not have the means to test for impurities)..and as
> expected: it isn't a easy world..;-)..
> ...
> I can think of the following things to explain the solarization:
> Stiil too humid? Too little metal?

If you do not find any specks in the print and the crystals are pure
red, then you likely have made a pure K2PtCl4. An important
consideration to help prevent the formation K2PtCl6 is to keep the
temperature below 140F (from chemist at Engelhard).

Both your guesses for the solariztion can be possible. One thing to
remember that can cause too little metal is that the correct solution
strength will likely require warming of the K2PtCl4 solution to keep it
in solution. (I put the solution bottles in a mug with water on a
coffee warmer.) The strengths typically used can precipitate out at
typical room temperatures (crystals in bottom of bottle). However, as
far as coating goes, I have found better success with the coating room
and paper temperature at about 60F during coating. Higher temperatures
(above 80F might also contribute to solarization). Another possibility
could be very high printing temperature, but this only seems to become a
problem when the coating is not dry (RH greater than 55%).

-- 
Jeffrey D. Mathias
http://home.att.net/~jeffrey.d.mathias/