Fire-Polishing – What is It?

Ivo de Croock wrote to us from Antwerp, Belgium, and asked what we meant by the term “fire-polishing”.

In the first place, we don’t etch with acid at our studio. (A colleague lets us use their studio for acid-work.)

But we sometimes etch by sand-blasting.

Now the sand abrades the surface of the glass and leaves it rough.

It’s now that we “fire-polish” the sand-blasted glass.

1. We put it in the kiln and fire the glass to about 710 c. / 1310 Fahrenheit.
2. We soak it there for about five minutes before descending and annealing.

This has two effects.

It smooths the sand-blasted glass.

It also softens the line where the sand-blasted glass meets the glass which has not been sand-blasted.

All in all, the glass seems to us to appear more like a liquid than it did before.

After the fire-polishing, we can paint and stain it as we normally would.

And this is what we did in the small panel of which you see an excerpt at the top of this post.