White film between Dichroic and clear code 96 after firing

I can't figure out what is causing small patches of white film between my dichroic and clear glass layers.  I don't think it is devitrification as it is on the inside of the piece post firing. And it doesn't look like air bubbles which I've also seen.  I'm using a 60 minute squeeze and long annealing and cool down.

White film

A couple things can cause the white film. At times if you use a window cleaner to get debris or oils on your glass, it may leave a residue which won't show up until you fire.

Another likely cause is when thin fire shelf paper is used, if your not ventilating the kiln when the paper starts smoking, it will get in between the glass and leave a smoky white film.

Im sure one of these will be the cause!  Let me know.



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