Re: Best CI for process

Mark,

When I evaluate a step wedge print made from a continuous tone step
wedge I count the steps from the first density over pure paper white
to the first shadow step that merges with the next one. Using the
pure palladium mix I described earlier I usually get about 12 steps,
which works out to a exposure scale of 1.80.

Sandy

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>Hi Eric,
>
>Just for reference, how do you figure your exposure scale? I know
>this sounds like a dumb question, but I have seen it defined
>differently by different people. Do you include the first paper
>white step also?
>
>Sandy, could you also respond to this question?
>
>Thanks,
>Best Wishes,
>Mark Nelson
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>
>In a message dated 10/3/05 1:03:42 PM, e.neilsen@worldnet.att.net writes:
>
>>Sandy, I don't use or test a pure palladium. The smallest amount of platinum
>>that I add is 15% of total metal salt solution. I make my own ferric oxalate
>>and use a palladium solution that is mixed at 5 g NaPd with 3.5g NaCl to
>>make 40 ml. This makes a .7 M solution to match my .7 M ferric oxalate. The
>>Platinum is a .457M solution in potassium version and .7M when I can get the
>>ammonium version. The molarity may be off by +/- .015 as these are from
>>memory but I don't think so.
>>
>>My exposure scale for the 1.0ml FO, .15ml K Pt, and .85ml Na Pd, is 2.45.
>>
>>I make most of my exposures after a 10 minute dry@ 100F and a 30 minute
>>humidification @60% RH. I process in Potassium Oxalate at both room temp of
>>70 and heated to 90F. The exposure test that produced the ES above was
>>processed at 70F.
>>
>>These test were also performed with Starphire glass in the contacting
>>printing frame.
Received on Mon Oct 3 15:00:42 2005