Thursday, 7 May 2009

Advice Required on two fronts Please

A customer brought this jug back today
to show me what has happened to it.
It looks to me like salt deposits that can be scraped off if you try very hard.
The lady has had flowers in it for the past two weeks, and she says there
was a small pool of water
under the jug when she moved it.
It was fired in my Gas Kiln late last year.
So I'm thinking it was not fired high enough.
I am going to make them another one but I wanted to know
if anyone else has seen this before.

On a more up beat Note I'm considering buying a new Wheel
and am thinking about getting a Shimpo Whisper T
any thoughts
would be welcome.

12 comments:

Hannah said...

Hi Paul, I have the 'T' like it a lot. The tray keaks like well like that jug by the sounds of it and doesn't hold masses before you have to empty it but apart from that I do like it very much.

Leaking jugs, try Clives mugs they sweat like crazy and so many other peoples that I won't name them all but loads of peoples do, part of what the material is. However stilts are marvelous things, I glaze a lot of my jugs and vases all over and fire on stilts. You could try that. As for the white bits, no idea, can't see them very well but even if I could I still don't think I'd have a clue. Sorry about that.

Christine--RHP said...

I fire to ^6, and one of my clay bodies does not vitrify at that temp. so if I leave water in a vase it does the same thing. It's the calcium depositing out of the pores of the clay/glaze. Looks like that's what's happening here. Also, I have an ancient Shimpo wheel and have used it for over 15 years with no problems. I think it was manufactured in the 1960's. (I know that doesn't help you much--)

potterboy said...

I have a shimpo whisper - not the T - and I like it very much - I bought the one with the lever so I can set it turning at a speed and not have to worry about it. I tried one out first though - we had one at the class. THinking of buying another.

Why aren't you using your kick wheels?

RE the jug, I have lots of pots like that - most of the earthenware mugs and bowls I have leave a sweat mark - one or two produce salts like that if left full for a long time. Glaze fit, porous body and time. I like H's suggestion.

Peter said...

One earthenware clay I used (but don't any more) had quite a high sulphur content. The result was "scumming", a white deposit on the fired clay and sometimes on the surface of the glaze. The manufacturer used to add barium carbonate to the clay body to clear this problem, but it didn't always work.

Probably a red herring but, I wondered if the problem could even be minerals in the water that the flowers had been in (ie from "hard" water) migrating through the pot. Good luck!

jimgottuso said...

i have a shimpo whisper, not the T. i love this wheel, never had a peep... very quiet, powerful and my favorite feature is that when you pedal off, the wheel head is disengaged from the motor and will move freely in either direction like a banding wheel. this seems like an extra that is not useful but once you get used to it, it becomes indispensable

Hannah said...

On the T you can put the pedal where you want it speed wise and then leave it, it stays there too ie I mean it isn't like a car accelerator if that mmakes sense.

potterboy said...

Yes, that makes sense H. I want something small that I can lift in and out so I can throw outdoors through the summer - I think the T looks the business.

Perhaps we can get a group together and get a discount...

Hollis Engley said...

That does look like some kind of salts or minerals leaching through the walls. Either from the clay body or - probably more likely - from the water the customer used in her jug. I've never seen that with the kind of high-fire stuff I do, though.

paul jessop said...

I'm quite sure it is salts leaching from the water that the customer has put into the jug. we have a vase that came out of the very same firing on the same shelf of the kiln, and that's had water in for the past month and it hasn't done that, but we do have a water softner, because the water is so hard around here.
I don't believe it could happen on a stoneware pot, any way not to worry I'm making another and we shall see if it happens again.
as for the wheel front. Jeepers they have gone up, the CTM price is now £627. plus VAT. so I'm going to put that Idea on the back burner for now.

doug Fitch said...

They look like little grit blows, has the glaze gone in those areas? I use a Rhode wheel, I've used both and find mine more responsive, but then it's because I'm usd to it I guess

paul jessop said...

Hi Doug I wondered what wheel you use. no the glaze is fine in all areas it's definatley salt coming out but drying very hard. it can be scraped off. and the glaze is fine underneath.

doug Fitch said...

Weird. Yes, will be there Wednesday, bring some pots if you like and I'll turn them brown for you in my next firing

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