Trying my hand at cascade pots

[vgarth]

Hi Ken, as you can see I did try grinding, don't know what it would take to "polish". Care to enlighten me?

And Edward, I don't really know why the kiln didn't reach temperature, since it did last time I fired stoneware, ony a few months back. But it's very old, and there seemed to be too much leakage where the lid was closed. It doesn't clamp, just sits there by gravity. I once tried to fill some slight damage to the top edge, where the lid meets the walls, with fire-clay, to get a better seal. Maybe I have to look at that again. Don't know.

I've bought a very old gas kiln, which is bigger, and finally just gotten it to working stage (Hooray) and maybe that means I'll only use this old electric one for bisque and small earthenware items. It's good for those temps. I think if one of the two elements had gone, it wouldn't even have made 1240.

Thanks for the interest everyone. Hope to post better pots in a 'gas kiln' thread some day within the foreseeable future.
Val Garth

[bonsaipotter]

Hey Val hang in there. We tend not to learn much from success anyway, just greedly accept it. Now failure, that,s another matter and besides you got a few that look very nice. I haven't got my mind around this heatwork thing either - time AND temperature, but surely 8 hrs at 1240 was always going to have a consequence.

The over-run would be due to the time for sure but the crazing would say something about the firing cycle - particularly the cooldown and/or the glaze composition. I've worked up a spreadsheet glaze calculator to try and keep my adaptions within the accepted bounds and am happy with the discipline it brings. These things are pretty cheap to buy as software packages and will change the way you look at glaze formulation if you aren't using one now. I'd say if you are doing what we do you'd just have to have one.
Also I had to cut down the feet on a couple of pots recently after they'd been throug glaze firing. They were just too big and out of proportion. Not sure what I was thinking. To do this I bought a masony diamond blade cutter to put in my angle grinder and with a steady hand it worked a treat.
Happy potter

[vgarth]

Thanks Happy Potter,
wow, were you angle grinding stoneware? Or earthenware? I think I could contemplate EW with an angle grinder, but doubt I could keep my hands steady. Or maybe after just the bisque, . . hmmm.

Anyway, I don't really know what you mean about a spreadsheet for glaze calculations. I have Excel, which is spreadsheets, but not what you mean I think. Do you mean there are software packages written just for potters? The program has some info about the physics/chemistry of glazing built into it? Or do you just mean keep meticulous records and make judgements based on them? I do keep firing records, but in a note form or journal form, not in a table or a graph format.

I do know what you mean about learning from failures; I used to fire that old electric kiln a lot, and well I thought, but looking back, I didn't have very high standards for success.

Cheers,
Val Garth

[bonsaipotter]

Hi Val,

The spreadsheet thing was about how to formulate a glaze for the characteristics you want. Yes just for potters.

It get's down to the chemical composition of the glaze components and works up a picture of the total glaze. Try a google search on 'Seger Glaze Formulation' or otherwise have a look at http://www.duncanshearer.co.nz/glaze/molecular.html . Get through all that and enjoy the science!
Glazemaster is one commercial software offering.

Yes the angle grinder was on the glaze fired stoneware. Bisque is prone to fracturing but the mature stoneware is more robust. The diamond blade is very thin and not at all like a regular cut-off wheel.

Cheers
Happy Potter

http://www.bonsaipotterycoy.blogspot.com

[kcpoole]

Hi Val
My thought was if can use a dremel, with a grinding wheel to take off the lumps where the glaze ran, then polish the edges so not dull so it lookls OK.

Ken

[mudlarkpottery]

Just use plain masonry discs with your angle grinder. Anchor the pot very well upside down and grind along the edges at an angle. I fire to 1280 and sometimes have to grind off drips from both the pot and the shelf.
Penny.

[vgarth]

Many thanks to Ken, Happy Potter and Penny once again.
Val