moldy clay weights

[blenderbender]

I have a nice 15 l crock that came with a set of unglazed clay weights which continue to plague me as they develop mold every time between uses. I thoroughly sanitize (bleach soak) and dry them each time before and after use. I can only assume that since they are porous that the source of the mold is now deep within and isn't killed by sanitizing or drying. First question that comes to mind is why aren't these weights glazed to begin with to prevent the penetration of mold (spores?)? I've just removed the weights from my kiln where I fired them to 1000 deg. F for 1 hr. believing that will kill anything that is still a viable source of contamination. Don't know all that much about mold but guessed that 1000 deg. should do the trick.

thanks.... Gary

[Christopher Weeks]

Ha! As I was reading, I was going to suggest you look for a potter-friend who could fire them. We once had a similar discussion here about a crock and that was my suggestion. I'm surprised that bleach didn't take care of it, but I'm really sure that if you soaked the weights at 1000F, there's no living tissue in them.

When you say they develop mold between uses, what does that mean? How does it manifest?

Make something now and let us know if that worked!

[blenderbender]

I wish I had taken a picture to post before I cleaned them off and fired them..... they'd been sitting dry in the bottom of the crock for a while now as I haven't fermented a large batch for some time. From what I recall it was mostly black patches, but there were other colors also. They were still stained after cleaning and then after firing it almost looked like patches of an ashy looking material had formed on the surface. It's beyond me what that might of been but I'm fairly certain it's all quite dead now. They just got cleaned off and dropped into my first attempt at whole sour heads of cabbage.

thanks.... Gary

[Dgocowboy]

Not saying this is what happened, but is it possible that the weights got moldy during storage? If they weren't totally dry, and were kept in a musty basement, for example, they might have picked up the mold spores from the air. I don't know if this happens, but it struck me as a possibility.

[dandelionwine]

I have the same problem and this is why i did not go on with fermenting. I tried with what is used to sterilize beer equipment and it did not work. I tried to boil them for a long time and it did not work. They are still smelly.
But reading the thread One idea occurs me: what would happen if I put it in the wood fire for a time? Would they crack? What is the reason they are not glazed anyway?
Otherwise I might contact the guys who make the crocks and ask.
It happened to me because I was taking the kraut out of the pot each time I ate some and I did not submerge properly and then it got moldy.

[Christopher Weeks]

If they suffer a thermal shock, they'll crack, split or shatter. A kiln brings things up to temp *very* slowly. Of particular importance is to drive out all residual water very gradually instead of just turning it all at once to steam. So putting them in a wood fire is a pretty dangerous course. Putting them in an oven at 200 and after an hour turning it up to 300 and after an hour turning it up as high as it goes is a safer option.

I still don't really know what's going on that would cause the weights to be prone to infestation once infested, though.

[Tibor]

I have a very close friend that is a professional potter. She fires her propane kiln at over 2200* and she says that an unglazed weight is just a tad more porous than a glazed one. I had her make me some unglazed weights and I used them a few times with beets and they did not pick up any stain.To fire unglazed weights you can stack a bunch of them in a pile.To fire glazed ones, you need to have these little pointy stands to put each of them on, so that they don't stick to the kiln shelf and they also might warp to boot. That is why, I believe, they don't glaze the weights and like I said, if you fire the weights at a very high temperature they are not very porous.

[Tibor]

After another discussion with my potter friend, this is my take away on the moldy weights. The moldy weights were fired improperly. My friend fires her kiln at cone 10 which is 2380 degrees. Every type of clay needs to be fired at a specific temperature to be properly vitrified. There is no one temperature to fire all clays--glazed or unglazed. Also purer types of clay will lead to less of a possibility of unwanted tiny pockets of impurities.
I would suggest, blenderbender, that you return those weights and ask for new ones. Properly fired unglazed weights should not be a problem.

[Christopher Weeks]

This doesn't affect the meat of what Tibor's saying, I'm not really disagreeing, just adding some trivia. It's slightly more complicated than "cone 10 = 2380F". In reality, firing to Cone 10 means that a pyrometric cone with the rating of 10 slumps well, but doesn't really melt. That will happen at some lower temp, if it's held there for a while, or at a higher temp for a short time. :-)