Pitting & Pinholing

Well a friend corrected pinholing by refiring to a lower temp. I think he had orininally fired to about 1200C and then refired to 1100C, but I can't be sure about the temps, it did however fix the pinholing. Good luck A

There is no real harm in refiring. I have done this to remove some pitting. I would let it soak for an hour. You may find that it also produces a slight colour change.

In article , Lindsay MacArthur writes

Should I fire at the same temp of the initial fire or should I fire at a lower temp?

LMac

That's what i thought a few weeks ago, i had a favorite mug which had an ever so slight chip on the rim. I reglazed the part and refired the mug: same temperature, same glaze, - it came out totally destroyed, glaze is rough, the writing on the side ran, everything else in the kiln was as normally, - i had that happen several times with refirings, so don't bet on it.

Monika

-- Monika Schleidt snipped-for-privacy@schleidt.org

Fire to the normal temp for the glaze in question - or even a little bit higher. I would first try to the normal temperature and give it a one hour soak.

In article , Lindsay MacArthur writes

i'm still breaking in a new gas kiln and a batch of pieces from the last fire had pin holing. this group was fired too low for bisque, and in the glaze fire they pin holed. i plan to use a runny glaze over the holes to "flux" these holes shut in the next cobe 10 fire.

it's only dirt anyway...

steve

steve graber

Simon, I tried refiring just once so far. It didn't help and some things trned out even worse. I haven't given up totally on the idea, but would like to share what I learned from this attempt. Through the help and advice of the great people on this list, I came to the conclusion that the reason why mine failed could be traced back to the bisque firing. The pieces that were the worst were from a bisque firing that had blown the breaker sometime during the firing. I was never able to determine for sure at what point it tripped, but I am sure I didn't reach ^04 and maybe not even ^06. Apparantly not enough of the impurities had a chance to burn completely out and they effected the glaze. I know that sounds somewhat simplistic so maybe the wonderful folks here would explain it better. But that's my experience with refiring. Enough to teach me a really good lesson on how important the bisque firing stage really is!

I just put in a load to refire. I am going ^6 with a 1 hour preheat and a 1 hour soak at the end. I'll let you know what my results are. LMac

Alas, the experiment was a failure. The pitting is worse. I hate that I can't figure out exactly what went wrong.....was it the glaze? was it the bisque? (which I've never had problems with before)....it seems like any number of things can cause this. Well, it just means I need to get back in the studio and start remaking this stuff because, of course, everything was for an order. One good thing though....I got some great colors after the refiring.

One last question...

Are there any structural and/or functional problems with pieces that have pitting and pinholing?

Thanks, LMac

Lindsay: Other than the obvious, that a piece should probably not be used for containment of food, (hard to clean) some people regard holes, cracks and other "natural" defects as enhancing a piece, rather than detracting from it. All depends on your sense of aesthetics, I suppose. Question for you... Was this any of the following:

a new batch of clay? a new batch of glaze? a new (to you) kiln or firing procedure?

If any of the above are true, I would begin looking there for the source of the problem, since you mentioned that you have not had this problem previously.

Don't necessarily consider this a failure. You may have just stumbled on something of value...either the surface texture or the "great colors". Might not be useable for this application (your order), but something you make in the future might just cry out for what you're not happy with today. Save one of those pieces as a "test sample" with the recipe and firing notes. You'll probably be glad you did at some point :>) I would think that more than 80% of all great "new" glazes are the result of someone's "accident".

Hope that helps, Wayne Seidl