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and now a word from howard axner

updated sun 18 feb 07


howard axner on thu 15 feb 07

As an interested and involved participant, I wish to provide =20
information that might bring more clarity to recent discussions about =20=

Nitride Bonded Silicon Carbide Shelves (NsiO).

I believe the discussion started when a recent order of Nitride =20
Bonded Silicon Carbide (NSiO) cracked after their initial firing, in =20
an electric kiln, from what we determined, after talking to the =20
potter involved, to be a forced, rapid cooling cycle. This could =20
have resulted from similar circumstances in any type of kiln =96 gas or =20=


The cracking issue subsequently raised the issue of safety. It is =20
true that some precautions should be taken when using NSiO shelves in =20=

an electric kiln, but when those precautions are taken, it is a =20
completely viable use. Just as you wouldn=92t retrieve toast from your =20=

toaster with a metal knife, you shouldn=92t insert of remove NsiO =20
shelves when the electricity to an electric kiln is turned on. =20
Unlike clay shelves, NsiO shelves conduct electricity, so the power =20
should be off, and any loose elements should be safely away from the =20

Details regarding the use of NsiO shelves are provided on http://=20 with =20=

some of the pertinent points including:
=95 Be aware that NSiO shelves are subject to conducting electricity
=95 Do not allow your shelves to get wet. If they do get wet, make =20
certain that they are very dry before firing.
=95 NSiO shelves are somewhat more prone to crack under severe thermal =20=

conditions than typical clay shelves

As with many other products there are both advantages and =20
disadvantages to using NSiO shelves. For those of you who are =20
unaware of them:

1. NSiO shelves are very thin and thus very light. Therefore, they =20
are much easier on the user=92s back when loading and unloading kilns. =20=

This is no small thing for many people and I thus I classify these =20
shelves as a healthy choice.
2. The thinness of the shelves allows more pottery to be stacked into =20=

the kiln and require less fuel in heating their mass. Thus I would =20
classify them as a =93green=94 product and as one that enhances =20
3. When used properly, these shelves will far outlast other types of =20
kiln shelves.
4. NSiO Shelves are far, far less subject to warping than other types =20=

of kilns shelves.
5. NSiO Shelves are capable of withstanding temperatures that are far =20=

higher than Cordierite Shelves, =93High Alumina=94 shelves, or ordinary =20=

Silicon Carbide (SiO) shelves.

1. NSiO shelves are more subject to thermal shock than Cordierite =20
Shelves. This is not a problem for most potters during the most =20
common firing cycles.
2. Some forms of NSiO shelves are subject to spalling or even violent =20=

explosions if fired when wet. Two very experienced potters in our =20
community, Bill Campbell, and Nils Lou have recently demonstrated =20
this with some other brands of NSiO shelves. We have tested our =20
shelves for this potential problem, and, to date, no similar problems =20=

have been detected. Our best advice is, don=92t let your NSiO shelves =20=

get wet.

As pointed out by one Clay Art contributor these new, thin and =20
lightweight shelves may not always be perfectly level. I have looked =20=

at a great many shelves, and, from my experience, they have appeared =20
to be within a reasonable and acceptable tolerance. Certainly the =20
benefits and great price make them a shelf of choice for many of our =20

In terms of customer satisfaction, the proof is in the pudding. =20
During the course of the recent Clay Art discussions, I have spoken =20
privately with a number of users of our NSiO shelves and so far, I =20
have gotten nothing but positive feedback. One of our users =20
indicated that it was the best pottery related purchase that he ever =20

Finally, I wish to re-address one more point that has come up on =20
several occasions during these discussions=85 the statement that Laguna =20=

Clay Company is an uncaring corporation. I have now been part of =20
Laguna for almost 8 months, and I find that statement inaccurate and =20

Our industry has grown and matured over the years and our supply =20
companies grow and mature too. Our growth and maturity have allowed =20
us to buy and distribute in ways that offer you greater variety, =20
better quality, and better prices. But by any generally accepted =20
modern economic standard, Laguna is, in fact, a relatively small =20
company with many competitors. In economic terms we have to provide =20
good products and good service at good prices in order to survive. =20
In human terms, all of the individuals that make up our staff take =20
great pride is serving you well and we get great satisfaction in =20
doing so. That is not to say that we never make a mistake, but we =20
work hard to avoid those and we correct them when they occur.

For those of you who had the stamina to read this long post, thank =20
you. If you care to correspond with me personally you may reach me =20
at and I would love to hear =20
from you.

Howard Axner=