While you can physically grind glass used in fusing projects, including glass that has already been fused, it is generally not recommended if you plan to refire the piece and want the edge to have a smooth, glossy finish. The process of grinding significantly impacts how the glass edge reacts during subsequent firings.
Why Grinding is Not Recommended for Fired Edges
Grinding glass creates microscopic scratches and a rough surface. When this ground edge is heated to fusing temperatures, it behaves differently from a smooth, cut edge.
According to one perspective:
"I don't recommend using a glass grinder for glass fusing as a ground edge rarely fires glossy. You may see a matte finish or a cloudiness resembling devitrification."
This means that if you grind an edge and then fire the piece, the ground area is likely to turn out matte rather than smooth and shiny. In some cases, it can even lead to a cloudy appearance, sometimes mistaken for devitrification (a crystalline growth on the glass surface).
- Matte Finish: The ground surface doesn't melt and flow smooth like a fire-polished edge.
- Cloudiness: A dull or hazy look can appear on the ground area after firing.
- Reduced Gloss: Unlike clean cut edges that fire to a beautiful shine, ground edges retain a duller texture.
Alternative for Shaping Glass Edges
If your glass pieces aren't the exact size or shape you need before firing, especially if you intend the edges to be visible and glossy, grinding isn't the preferred method.
The reference suggests a better approach:
"If your pieces aren't the size you need them to be, it's often better to nibble the edge into shape with a grozing pliers."
Using grozing pliers allows you to carefully remove small pieces of glass, shaping the edge without creating the extensive surface abrasion that a grinder produces. This method is more suitable for preparing edges that you want to fire to a clean, glossy finish.
Grinding Fused Glass (Coldworking)
It's important to note that the discussion above primarily pertains to grinding glass in preparation for or during the fusing process where edges are intended to be fire-polished in a subsequent firing.
You absolutely can grind fused glass after the final firing as a coldworking technique. This is commonly done to:
- Smooth rough edges from cutting.
- Shape the finished piece (e.g., creating bevels, curves).
- Prepare edges for assembly or display.
However, grinding a finished fused piece is done after the firing process is complete, and the ground surface remains a coldworked surface – it will not become glossy unless it is polished to a very high grit or potentially fire-polished in a separate very hot fire-polishing cycle (which is different from a standard fusing cycle and carries risks).
Summary
| Action | Recommendation for Fused Edge Finish | Result After Firing (if applicable) | Alternative Suggested by Reference |
|---|---|---|---|
| Grinding before final fuse | Not Recommended | Matte, Cloudy, Not Glossy | Grozing Pliers |
| Grinding after final fuse | Acceptable (Coldworking) | Remains Matte/Coldworked (unless polished) | N/A |
In conclusion, while grinding glass is a viable technique in glass work, including working with fused glass, it's generally best avoided on edges if you want them to fire glossy in your fusing projects. Opt for grozing pliers for shaping unfired edges instead.
