What am I missing here?

[Stephen Richard]

Anything put between the glass layers will remain there in some form.  Always.

If you mean to fire in two stages it is possible, I suppose.  Possible is putting the frit onto the fibre paper and capping it with a sheet, firing to tack fuse, remove and clean.  Then fire over base layer, with long bubble squeeze, might get your result.

Trying thinfire or any ceramic fibre paper will leave residue of the paper inside the glass.

Stephen Richard

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