Cerium oxide, combined with
Cerium oxide, combined with some water and heat, chemically bonds to the glass to fill the ultrafine scratches left behind by the previous abrasive (typically pumice). That heat – which is a result of friction – may be what you are remembering. That little bit of warmth (just warm to the touch – too much and you can thermal shock the glass) is a far cry from fire polish temps.
Helios Kiln Glass Studio