Re: 4-color carbon question

Luis Nadeau (nadeaul@darwin.nbnet.nb.ca)
Sat, 9 Dec 1995 23:59:56 -0400

>>Do you pre-wet the black before attempting the final transfer onto your
>>magenta?
>>
>
>Yes, the black is assembled under water (52 degrees F). It is immersed for
>60 seconds.
>
I am pretty sure this could be cut down to 45 seconds and even 30 seconds.
Try it. With the old processes that used pigmented *papers* they came up
with a wringer that sandwiched DRY tissues to the *DRY* support, just
pouring some water over the image surfaces as they were brought into
contact going through the wringer. Yet, this created enough swelling of the
gelatin layers to make them stick tenaciously together. The idea here was
to avoid 60 second or longer soakings of the *paper* tissues as they
obviously expanded and contracted unevenly after such operations.

>>What about the three color image with the magenta on top of it? How long do
>>you pre-wet and at what temp?
>
>The receiver with the 3-color image on Melinex is immersed 30 sec. before
>the pigment sheet for a total of 1.5 minutes.

again, this may be cut down. Just make sure you change only one variable at
a time however.
>
>>>>> magenta inhibiting adhesion?

>>Note that overexposure of the black can also be the cause of your problem.
>>Also, make sure there is no extra hardening (in a chemical hardener, e.g.,
>>chrome alum) between transfers.
>>
>
>No hardening is done. The black only reaches a Dmax of 1.4 to 1.6, I don't
>feel it overexposed.

Well, that depends. Give it another say, 25% longer exposure and then try
another test with 50% and then 100%. If all three tests give you the *same*
density, then your original one may be overexposed. If 25 and 50% give you
*more* density, then your original exposure *may not* be overexposed, but
the only way to find out for sure will be to cut down the exposure of that
one as well.

The idea here with the *black* printer is to give it just enough exposure
so it does its job. Going beyond that and you may run into the problem you
have where it refuses to adhere to the receiver sheet.

BTW, I hate to scare you but all these parameters may change if your
gelatin source is changed significantly, say if the Bloom from one type
goes from 250 to 200.
>>
..

Luis Nadeau
awef6t@mi.net
nadeaul@nbnet.nb.ca
http://www.primenet.com/~dbarto/lnadeau.html#A0