Trouble with glazing, unglazed pots

[AndreaB]

Good morning to you all,

I'm having a great deal of difficulty with getting my glazing right. A year ago everything was fine, I had a back op last October and have had problems ever since then. Took a break from throwing but came back in Feb, since then I've had one hand done for CTS and the other is on it's way to being done. Since the op my sciatic nerve has been damaged so I have problems with throwing, and indeed pain is probably one factor that is affecting my glazing.

I was making forms that were hand built tall vases, glazing became a problem due to the length of time it takes to fill the vessel, put down the jug and then empty the vessel (splashing glaze every where). This done my insides are always too thick leading to major crawling. Was glazing the outside by dipping half and half (top and bottom), leading to thickness around the overlap, Did rub down, but still came up with spots of milky glaze.

Now the next step. I used Amaco PC brush on glaze for two new projects, the one has milky streaks and crawling. It was fired stoneware, bisqued to 1000deg C, Glazed to 1200. The glazes used indicate cone 5-6. They were set on the floor of a small kiln (no elements under it). It is possible that at that position the heatwork was not enough (cone did not bend). What should I do now? Refire and raise the vessel to higher point, and what about the crawling, should I try to glaze those spots or should I make a decorative feature by using luster? Give up and rethrow?

Thanks for listening

 

On the other hand, what would underglazed but not glazed work do for me? 

[Pres]

Andrea, what temp was the pot bisque fired to? The glaze looks a tad think in areas, and I understand the problems with larger forms, but the brushing. .. Has this pot  sat for a long time? What was the pre glazing process or wash down?

 

best,

Pres

[Gabby]

I am a novice, but I use those brush-on glazes all the time. This looks like the Chun Plum,  which I find the hardest of those glazes to use.

Unlike most of the others, it starts out really thick. I have had something like this happen in glazing when I apply glaze that was inadequately thinned in the first instance.

[JohnnyK]

Considering your continually changing physical limitations, Andrea, it might be an idea for you to make smaller pots that are easier to handle. Working in pain is no picnic particularly where back pain is involved, but you are also talking about your hands, too. I had both my thumbs operated on and it took almost a year to fully recuperate to where I could work on the wheel again. I missed having my hands in the mud, but it was well worth the wait to be able to throw without pain. 

The problem you show here may be a little oil or dirt on the pot that caused the voids. You have nothing to lose by trying to touch up the glaze in the bad spots and re-firing, but you would have to be sure that the piece is fired to the proper temperature as indicated by the cone bending properly. If it doesn't work, you are no worse off that you are now.

JohnnyK

[neilestrick]

You don't need to fill the entire jar to glaze the inside. Pour some glaze in, and rotate the pot as you pour it out so it covers the entire inside. You could also try thinning out your glaze a little so it doesn't go on so thick. Do the inside, wipe off any that glaze that dripped on the outside, then let it sit overnight before dipping the outside.

The crawling on the outside may be thickness related, but it can also happen if the pot is too saturated after glazing the inside. It can also come from oils on the pot, like if you had lotion on your hands.