View Single Post
  #9  
Old 05-10-2020, 09:40 PM
Hugh Jenkins Hugh Jenkins is offline
Registered User
 
Join Date: Sep 2006
Location: Honoka'a, HI
Posts: 1,007
Hugh Jenkins is on a distinguished road
Keeping track of zeros is really important in calculating color, and especially with cobalt. Diluting with silica to make powder blue makes slight errors less impactful, but parts per hundred or thousand or ten thousand are way different so do the math well. A mistake of grams of cobalt oxide in any formula is astounding.

I totally concur with the heat judgement with slight color in the glass. I always started the beginners with remelted scrap. There would be enough color from the pipe slag and color being used in the lab without any additions. The color would be slightly different every day, but copper, chrome and cobalt generally set the tone. One bonus of slight tramp color is that reactions with silver or other oxides is emphasized.
__________________
Aloha, Hugh
Reply With Quote