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Member Since 04 Oct 2011
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#115039 Blisters Worse After Re-Firing

Posted by neilestrick on Yesterday, 07:43 PM

Agree Babs:  but he said "unstable glaze- not enough alumina and/or silica." Alumina and silica are refractory materials. Depending on the ratio of flux/ refractory materials, the melting point will rise and fall.......  I took a short cut in my explanation. hope it is now clearer what I meant. 


Yep. If it was fired cooler it might be fine, but at that temp it needs more silica or alumina to stabilize it. If we had the recipe we could compare it to limit formulas, but without a recipe you could run tests adding equal parts alumina and silica in 2% each increments. At some point, if that really is the problem, the craters will stop. Equal parts clay and silica will generally keep the si:al ratio the same as the original, or at least very close.

#115038 Kiln Shut Off Too Early - Can I Refire These Pots?

Posted by neilestrick on Yesterday, 07:23 PM

As long as the glaze didn't crawl, you can refire them with likely success.

#114950 Perfect Fit For A Lid.

Posted by neilestrick on 20 October 2016 - 09:47 AM

I get what you're saying, but- lids should dry on the pot, so if the lid is so tight that you need to grind them together to get a perfect fit, then there's a chance of cracking the rim of the pot as they dry or the lid getting stuck.

#114931 Homemade Gas Updraft Kiln, Not Enough Temperature Any Help :)

Posted by neilestrick on 19 October 2016 - 09:40 PM

Are you saying you don't have an exit flue? All kilns need an exit flue. Heat has to move through the kiln, with enough air to feed the combustion. You shouldn't have any carbon buildup, especially at low temps. I can't really tell what's going on from your photos, but I would recommend getting a kiln building book to learn about how to build one properly. There are certain 'rules' to follow if you want it to work.

#114700 Quickest Way Of Making An Enclosed Form?

Posted by neilestrick on 14 October 2016 - 12:51 PM

If you want to hand build them, I'd find some bowls that are the right size and use them as  slump molds. Lay slabs into it and join them up once the've firmed up.

#114691 Blisters Worse After Re-Firing

Posted by neilestrick on 14 October 2016 - 09:33 AM

Have you used that glaze before? Does is have this issue often, even a little bit?


To me it looks like an unstable glaze- not enough alumina and/or silica.

#114649 Concerns About Wood/anagama Kiln Smoke Vs Neighbors...

Posted by neilestrick on 13 October 2016 - 09:39 AM

Some areas consider kilns to be just like open burning. Others think of them as barbecues. Others consider them an industrial process. It just depends on where you live. Even if they allow the kiln, don't buy anything until you check on what building codes will apply to it, such as location restrictions like boundary setbacks, chimney height, etc. There are lot of potential limitations that may make it difficult or impossible to build. I would have a kiln plan ready to show them, since they probably won't have a clue what you're talking about.

#114627 Concerns About Wood/anagama Kiln Smoke Vs Neighbors...

Posted by neilestrick on 12 October 2016 - 09:37 PM

Certain types of kiln smoke more than others. The long slow types like anagama tend to be smokier than faster firing, more efficient designs like a train kiln or a cross draft kiln. In grad school we were required to fire with as little smoke as possible, since the kilns were right in the middle of campus, and it wasn't a problem with the types of kilns I just mentioned, other than during body reduction. Every type of kiln will smoke to some degree, however, so you want to do some good PR work with your neighbors. Invite them to help stoke, let the make some little pots and put them in the firing, provide lots of beer, etc. If done right, it will likely smoke less and be less of an annoyance than burning leaves.


On that note, check with local fire codes and building codes before buying a house. Have a conversation with the fire marshall about exactly what you plan to do, and get things in writing.

#114560 How Long Do You Like To Be In The Studio?

Posted by neilestrick on 11 October 2016 - 07:50 PM

Longer than I usually am.

#114558 Anyone Deal With Buying And Shipping A Kiln From Clay-King?

Posted by neilestrick on 11 October 2016 - 07:42 PM

The kiln will ship in the original packaging from Skutt. Clay-King will not unpack and repack it. When the kiln arrives, inspect the outer box for damage. If there is any, note it on the bill of lading with the driver. If the driver will stick around for a few minutes, remove the outer box and inspect the kiln. If there's obvious major damage to the kiln, refuse the shipment. Technically, you own the kiln once it's shipped, however the place you bought it from will help you with making claims. The kiln manufacturers and all the clay suppliers have relationships with kiln techs, and will often just have the freight carrier pay for a repair rather than replacing the entire kiln. I've done that several times on kilns that were not purchased from me, and kilns that were damaged by moving companies. Clay-King may not have those relationships, and would rather just replace the kiln. As long as the obvious damage to the packaging is noted on the bill of lading, making claims is easy. It's also good to take lots of photos as you unpack the kiln. But round kilns are rarely damaged in shipping.


You could also ask your local supplier to match Clay-King's price. They can do it, and will probably be happy to sell it at a lower price rather than miss out on the sale.

#114555 Glaze Dripped Onto Kiln Floor

Posted by neilestrick on 11 October 2016 - 07:02 PM

Pots should never be fired directly on the kiln floor. For starters, it will often run cold at the bottom if you don't put a shelf down there an inch or so off the floor. Second, it's much cheaper to replace a kiln shelf than a kiln floor.

#114359 Stoneware Limit Study

Posted by neilestrick on 05 October 2016 - 04:34 PM

Most view porcelain as being tough to blend, I think stoneware is much more complicated because there does not appear to be any cohesive parameters.




Bingo. Porcelain tends to be more consistent because there are specific parameters that define porcelain and therefore fewer options on how to make it. Stoneware is pretty much anything that's not porcelain or earthenware, which is an incredibly broad definition. The possibilities for formulas are infinite, and it's very often formulated specifically for how it's going to be fired, which is not usually the case for porcelain.  A porcelain will work in either reduction or oxidation, but a brown stoneware intended for oxidation may be much too high in iron for reduction. Porcelain is good for some things, but awful for other things. Stoneware can be formulated to work in any situation. As mentioned before, wood and salt bodies tend to be lower in silica to encourage flashing rather than glossiness. Sculpture bodies tend to be very groggy to allow for thicker and less consistent construction, whereas white stoneware throwing bodies are smoother than porcelain. It's like dog breeds- they're all dogs, but each one has its own appearance and function.

#114348 Wedging Clay

Posted by neilestrick on 05 October 2016 - 11:23 AM

I find that most of the clay bodies that we use in my studio are useable right out of the bag without wedging. The key is to cut a cube off of the big block, which can then be made into a ball without folding it up and trapping air bubbles. If you cut a thin slab off the top of the big block, it will need to be wedged. Porcelain always needs to be wedged.

#114302 Stoneware Limit Study

Posted by neilestrick on 04 October 2016 - 09:06 PM

The discussions around grog in clay body formation tended not to be in terms of what the grog added to the melt (except in soda/salt firing), but its primary use was for workability in a clay body. More temper means the clay is more structurally sound while being made into large pots. It won't slump or warp so readily while drying or being formed.


This is a good example of what I meant in my previous comments. Stoneware clays are all over the board in terms of particle size and random additions intended to increase workability. I'm very interested to see the affects of these materials.

#114271 Cone 4 Oil-Spot Type Glaze

Posted by neilestrick on 04 October 2016 - 02:49 PM


IMG 20161004 144557
You can definitely see that thickness matters. The top half is double-dipped. It can be applied even thicker, which gives large spots.