Glaze remelting/refiring

Not stupid question at all. The second firing of a glaze is not the same as the first. Before the first firing you had one set of chemicals. After the firing you have a glass which has undergone chemical changes. Your Carbon, Sulfur, Nitrogen, etc. have all been removed from the glaze. It isn't even that you have a frit because glass is oddly a liquid in many ways.

Also the second fire may not get rid of your blisters - it may in fact make them worse.

If you can sand the blisters down as much as possible and then coat them with a glaze that tends to be a bit on the runny side... maybe. JMO.

Good luck and enjoy your visit!

Donna

Hi D! Thanks for the quick reply!

So far, with my glazes, a second firing has never made them worse. I see what you mean about substances being gone. None of my glazes are runny, though - the only thing is the beautifier, and that has caused many craters in the past, so I don't trust it much these days. Mind you, I think I was putting it on wayyy too thick.

Would setting top temperature a couple of degrees higher help in melting the edges of the craters?

Marianne

Your glaze in the second firing is actually going to be melting at a lower temperature so unless the firing was at too low a temperature for your glazes to begin with then my answer would be no. I would not increase the temperature. This is one of those cases where you just have to play with it and see what works. As I remember you said that you used a really long soak. If not, I would try soaking at top temperature but keep in mind that the soak is going to increase your heat work (making it a higher firing than what you would have without the soak) so you might actually want to drop the temperature some (8 C). I would soak at least 10 minutes but over soaking is hard on your elements.

Donna

can you sandblast the objects and recoat with the same glaze, then refire to the same temp?

Seeing as the glaze bubbled the first time, it might well do it again, so I would be careful with that.

Also, "just" grinding the pock marks down and then adding a little glaze to those areas has worked for me before.

Marianne

I think I am on the trail of the cause for MY pock marks now - the soak temperature. I tried 1240 - there were less pocks - I tried 1245 and there were more again. This kiln today is going to soak 30 minutes at 1235.

I am making it a bit harder for myself in that I use different glazes and combinations of glazes most of the time - so that I have to look at all angles of the firings and glazes to see what works where. I am making exacting notes these days, though, so I can track many aspects I wasn't able to before.

I'm sure I'll be back talking to you before the holidays, so I will just wish you happy glazing for now! :-)

Marianne

not necessarily. if the gases (or the components of the minerals that produce the gases) that caused the bubbles are gone, then only the newly added glaze would cause bubbles, if any.

Which is why I would rather keep the old glaze as much as possible.

Marianne