Jeffrey D. Mathias (jeffrey.d.mathias@worldnet.att.net)
Tue, 19 Jan 1999 09:00:18 -0500
joel lederer wrote:
>
>... When making smallish
> (4x5) prints I don't have very much control over the contrast because
> the number of drops (of A and B) is so small. ...
> 1)Are there any problems in making a concentrated K. chlorate solution
> in water? e.g. solubility, keeping qualities, safety
>
> 2)What would be a good % solution(s) to begin with. The dropper method
> uses a .6% solution but since this is mixed with F.O. , and because I'm
> mathematically limited, well you get the picture.
>
> 3)How much of foreign solution could be added to the sensitizer w/o
> running into problems?
>
> 4)Has anyone used this method or a similar one? (perhaps using a
> different oxidizer)
Joel,
Instead of one concentration, of K chlorate, I have found it more
convenient to use multiple concentrations. Only one drop is added at
the time of coating mixing. DO NOT premix and store the K chlorate in
the sensitizer or metals, keep it separate. And, even if a pipette is
used for the other chemicals, use a dropper with only one drop for the K
chlorate. The one drop of a premixed solution gives incredible control
and repeatability.
For various sized prints (2x2 to 8x10) solutions ranging from 0.1% to 2%
should be fine. Add one drop of the solution at the time of mixing the
coating. NEVER pre mix the K clorate into the sensitizer.
Whether a drop is added to 8x10 or to 4x5 makes no difference, The
small difference of water will evaporate anyway. What is important is
how the coating is put onto the paper. By whatever method is used, one
must avoid wasting the chemistry by pushing it past the image area.
Work it into the paper without damaging the paper. However, it's not
desirable to have it go through the paper.
And, I have found that a single coating, done properly, will give the
best results achievable. If prints are weak, most likely not enough
chemistry is being used or it's being spread too thin and dumped on the
edges. However, too much chemistry can cause problems as well (such as
puddling, blotches, "bronzing look")(this is where drying the coating
properly is important).
Zero foreign solution should be added to the coating solution.
Distilled water is not foriegn.
When adding a contrast agent to the coating (and I use several), I have
always used the One Drop Method. I have also added contrast agents to
the developer. When added to the developer, it must be taken into
account that the contrast agent will be depleted requiring some sort of
replenishment schedule. I have found the In The Developer Method to be
less accurate, but it gives results different and not possible with the
One Drop Method.
-- Jeffrey D. Mathias http://home.att.net/~jeffrey.d.mathias/
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