Mostly c, but sometimes g
B and/or C (Cr2O3)
Usually F, sometimes B, E on occasion (sheath from the borosilicate rod).
Though I could not caution all I still might warn a few; Don't raise your hand to raise no flag atop no ship of fools. - Robert Hunter
If you reach the age of 60 without becoming a curmudgeon, you haven't been paying attention.
C and G (felt) but I bought some balsa last week and I am going to load it up with chromium oxide and try that too.
"What happened to those other underpants you had?" -- Flight of the Conchords