|
|
|
-
I talked to one of the engineers who worked on glass plates and he said that nothing was as good as chrome alum for adhesion of emulsions to glass. It is also rather slow in action, as sometimes emulsions were stored for a few days with the chrome alum in them already. IIRC, this is mentioned in several text books.
However, the pH is critical in the coating. Too much acid or alkali will upset the effectiveness of chrome alum.
PE
-
 Originally Posted by dwross
And, Kirk: magnesium carbonate and don't you dare laugh.
Magnesite? Dolomite? Chalk? Exlax??? Oh, for the flubber emulsion... OK, I promise not to laugh...
-
Originally Posted by Photo Engineer
[..] this is mentioned in several text books.
However, the pH is critical in the coating. Too much acid or alkali will upset the effectiveness of chrome alum.
More info please...
-
I'll leave that as an exercise for the student. Y'all have all of those textbooks. 
Seriously, the pH should be about 6.3-6.7 for best results. To far acid and it does not work, and too far alkaline and it sets up too fast. I've had chrome alum melts set up just by adding some addenda.
Trial and error is all I can suggest right now.
PE
|
|
Adv Reply
