I did not find written information regarding fusing soda ash between two layers of glass in an electric kiln.
Our studio recommended experimenting with it yourself. The Warm Glass website has instructional information that should help:
https://www.warmglass.com/category/tutorial/
They have written that using baking soda is used commonly to create bubbles between fused sheets of glass.
I attached our bibliography on "inclusions" for general instructions on lots of different types of inclusions.
Please write again in you would like more information about soda ash and its use in glassmaking.
Thank You!
