Dennis,
Alot of the time the only difference between reagent grade and technical
grade is that the reagent grade is analyzed, meets certain
specifications, and has the amounts of typical impurities listed on the
lable. Most of the time the technical grade will work fine. For 500
grams of potasium dichromate the difference in price is about 18
percent. (the reagent grade being more exspensive.) This may or may
not be important.
Now this may be important: Sodium dichromate is generally 1.6 times the
cost of potasium dichromate. (60 percent more costly) I have been
useing potasium dicromate as a contrast agent.
The most consistant way is to mix several bottles of enhancer (I call it
enhancer rather than developer because of its fuction) with various
percentages of potasium dichromate. Try the percentages .001%, .0025%,
005%, .01% Much stronger will most likely be too much for a good
negative and less will have about no effect.
CAUTION: either potasium dichromate or sodium dichromate are dagerous
and gloves are recommended. Especially do not get in a cut or break of
the skin.
Another method I have tried with success is to add a drop of dilute
potasium dichromate Jeffrey.D.Mathias@worldnet.att.net (to result in the above percentages) to the coating
mixture. This gives excelent results on sharp textures like bricks.
However, the dichromate does end up in the enhancer changing the
characteristic of the enhancer as each print is processed.
Jeff
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