Black stain on the parting tray

C

crauther

New Member
#1
After the annealing of the cornet, i could see some kind of black stain on either side of the parting tray, and even on the thimble. How could i get rid of from the "black stain" and what caused this uneven color on the tray.
 
fireguy

fireguy

Supermoderator
#2
After the annealing of the cornet, i could see some kind of black stain on either side of the parting tray, and even on the thimble. How could i get rid of from the "black stain" and what caused this uneven color on the tray.
I would think the stain is caused either by heat, or perhaps some of the nitric acid parting solution got on the tray?
 
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