Sprayed glaze seperation

[Seesee]

Hi again!

just got a new kiln and refired a peice that didn’t quite reach temperature sometime a couple years ago. I spray using a manual pump gun and have never encountered this problem before, although I have got very thin edges which come out white. Not intentional but I thought looked nice. This on the other hand is really not it. Any suggestions on what I can do to fix this and why it’s happened?

 

 

[Min]

Glaze crawling is usually from one or two main causes. Either the glaze was too thick or the bisque was contaminated with dust or oil (from skin or hand lotion etc). Crawling can also happen when the recipe contains too high an amount of a material with excessive shrinkage but it doesn't sound like thats it in this case. 

[Hulk]

Look also for the glaze layer cracking as it dries on the piece - some glazes will, err, can run together when they melt, others pull apart along the crack lines.

[Seesee]

Thanks so much, I will try to look out for this in the future

[Morgan]

As Min points out more like contaminated bisque as some of the glazes don’t at least look that thick. Are you cleaning your bisque with a damp sponge (or dunking them in water)? Also, I am neurotic about keeping my hands cleaned on glaze days, it’s actually quite funny. I don’t think this is that, as it would be a finger dab here or there, but it’s just a reminder that any little wipe of the nose, your pet etc can unintentionally add oil to a bisque piece and ruin your glaze. 

[Seesee]

Hi Morgan 

No I never got into the habit of wiping my pieces down before glazing as I’m usually in such a rush to get things in the kiln. This was some time ago when I used to work in a studio and the piece didn’t reach full temp so I refired it and this is what happened. I reckon I contaminated it with moving it from A to B but will take more care in the future. I thought it was something to do with firing it twice!