Re: Carbon Printing/Daylight Tubes
s carl king (sanking@hubcap.clemson.edu)
Wed, 17 Jan 1996 13:03:48 -0500 (EST)
>
> I have tested the three dichromates, potassium, ammonium and sodium
> against each other. As far as I could tell -- and as whatever source I've
> read on the subject has asserted -- the differences in contrast are a
> result of the difference in *solubility.*
>
> That is, potassium dichromate is the least soluble in water (15%?),
> so it has the least dichromate per unit & the least sensitivity; ammonium
> dichromate will make about a 26% (29%?) solution, and is more sensitive;
> sodium dichromate I believe goes to about 50% and so is the most sensitive.
>
This is my understanding and experience with ammonium and potassium dichromate,
in fact I read somewhere and have approximately been able to verify
the results, that 117 units of potassium dichromate can be substituted
for 100 units of ammonium dichromate in the same solution to give
equivalent results. I have no expereince with sodium dichromate but my
understanding was that a saturated solution was 70%. That is why I
said it was more sensitive than potassium and ammonium dichromate.
Sandy King
>