Re: self masking and POP

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From: Judy Seigel (jseigel@panix.com)
Date: 02/09/03-01:09:41 AM Z


On Sat, 8 Feb 2003 Ender100@aol.com wrote:

> Hi Judy,
>
> This was with Pt/Pd..... and I wasn't testing for that, just noticed that the
> clear portion of the Picktorico caused the pt/pd to print lighter than the
> clear portion of the stouffers laying next to it.
>
> Maybe I had the NUARC plugged in backwards. hehehehe or maybe it's different
> with cyanotype.

Well it seems to be... I tested a bunch of different substrates to see
which held back light most, on cyanotype.

Firstly: The little rosy red gelatin passed through more light than the
blue gelatin I mentioned the other day. so there goes another theory down
the tube... The base of plastic these gels were on (I think actually
they're gelatin all the way through) held back very little light... the
blue held back about the same as the pictorico, which held back a tad less
than the Stouffer. The red held back-- not dramatically more-- but easily
to the so-called naked eye, more...

I also tested some clear plastic used for graphic arts, "antistatic," had
almost no light blocking effect at all...and half a dozen other materials,
usual suspects, no great surprises.

I think the actual light blocking effect isn't significant (except the
Epson black light is major), after all you adjust for it in exposing, but
it may affect the curve.

One other thing worth mentioning however, for folks who oil negatives:
The difference between negatives (paper, and other materials) oiled 3
months ago and oiled the same day was striking. I knew already it starts
to dry out after two days... but it seems to keep on drying.... And it's
not just that the oil dries out, the curve changes as it dries.

Then I coated some paper with dichromate to see if it's the same as
cyano, but forgot it in the water & it washed away mostly... but before I
soaked it, looked like the red ALSO let through more light than the blue.
As Mark would say: "heh heh" !!

cheerio,

Judy

>
> Mark
> In a message dated 2/8/03 4:31:13 AM, jseigel@panix.com writes:
>
> << > When testing some Pictorico step wedges, I found clear Pictorico film
> blocked
> > the NUARC more than the clear areas of the Stouffer's. I didn't run further
> > tests, but I suspect it has a greater ability to do this.
>
> I found that not so in cyanotype... pictorico blocked slightly less than
> Stouffer... >>
>
>


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