Re: Standard formula

Hello Patrick,

Welcome to the list.

>
>2) The most confusing item I have run into is pigment concentrations.
>Sandy in your carbon primer you suggest 40 g of sumi ink. In your tables
>regarding various concentrations of dichromate you state 40ml sumi ink. I
>thought that 40 ml sounded more likely and mixed my first batch using 40 ml.
>Now, after reading these latest posts Im back wondering which is correct.

With Sumi ink the two are for all practical purposes the same, that
is, 40g of liquid sumi ink is almost exactly 40ml.

>
>3) Back to the pigment issue. Some times you guys ( lovingly said) refer
>to lamp black and carbon as the same thing.

Lamp black is a carbon pigment and was the original pigment used to
make carbon tissue, hence the name of the process.

>
>4) Also pigment thing. Are you using dry pigments or watercolor pigments
>from a tube when weighing in grams. I realize I maybe being very dense
>here.

We are doing all of those things, and of course it is important to be
specific in terms of type to avoid confusion. Even more, it is
important to be specific in terms of brand name in many cases as the
actual opacity of pigments of same name but different manufacturers
can vary quite a bit.

>
>Sandy... You state in your contrast charts that you add ammonia until the
>dichromate solution turns yellow. Should that be a few drops or are we

This varies from a few drops for very dilute dichromate solutions
(1/4% to 1/2% to as much as 100ml per 1000 ml for strong (6% and
more) sensitizers. However, the change from potassium dichromate to
potassium ammonium dichromate is quite dramatic as the liquid
changes quite suddenly from reddish orange to a pale lemon yellow.
You could only miss it if you went to sleep!!

>looking at ml here? How will I know if I dont have enough or too much?
>
>I have been bugging Dick about getting more copies of your carbon book. Any
>idea when he might have them in his little hands (LOL).

Yes, I am going to mail some more copies of my manual to B&S tomorrow.

>
>On a more personal note. My fathers family is from Anderson and the
>surrounding area. Also my father is an active alumni of Clemson University.
>He was up there a couple of months ago to attend one of clemsons more
>notable football games ( he played on the football team also, I think).
>

So with all that tiger in your blood how did you avoid winding up at Clemson?

Regards,

Sandy

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