Are you grinding the

[Stephen Richard]

Are you grinding the edges?  That promotes devitrification unless cleaned very very very well.

Unless circumstances dictate otherwise, I normally groze my glass if I didn’t cut it accurately.  The heat of the kiln will smooth out any little edge imperfections.  Different of course if the glass pieces are butting in the middle.

Stephen Richard

blogs at: http://www.verrier-glass.blogspot.com/   and  http://www.glasstips.blogspot.com/