Main Discussion Area > Primitive Skills

Pottery at Pete's

<< < (4/12) > >>

nclonghunter:
Hey Zuma, found this article about shells. Explains it better than I can,

I poured the crushed shells in a cast iron pot and placed it on a gas range. Steam quickly began rising from the shells. Hydrogen sulfide could be smelled as it was driven out. Then, as the shells turned white, there was an odd odor. I leaned over to sniff and saw stars. Fortunately, I had about three seconds to cut off the burner, before completely blacking out. I woke up on the kitchen floor about 30 minutes later. This obviously is an experiment that one should not try at home.

Eventually, a friend, who is a chemical engineer, figured out what had happened. Freshwater mussel shells contain chemical impurities that are not present in sea shells, particularly in their mother-of-pearl inner surface. When heated to over 500 degrees those chemicals react to create cyanide gas! Methinks that the young lady at the University of Alabama was either trying to make herself immortal by entering the Guinness Book of World Records through the most anthropology students killed at one time, or she really, really didn’t like her ex-boyfriend, the married professor. I could see her fluttering her lovely Alabama Belle eyes and demurely uttering, “Some more hot, crushed, Black Warrior River, mussel shells my dear?”

nclonghunter:
More good info;

Instructions from the Alabama Belle with a death wish, said to fire the shell-tempered pottery to at least a cherry-red temperature and hold it there for two hours. What temperature is cherry red? All pottery turns “red hot” when being fired. I guessed she meant “earthenware temperature” and placed the appropriate temperature cones in my kiln.

The Maya tripod pot fired beautifully. There was not a flaw. The pot pinged like the finest porcelain. It glistened like a Corvette with candy-apple enamel on it. As soon as the pot cooled enough to pull out of the kiln, I photographed it, and sent an email to the tribe’s Mikko (Principal Chief) to brag about the gift that was coming his way.

The next afternoon, I happened to glance at the pot. Hairline cracks were forming that gave it the appearance of raku pottery. I didn’t understand how cracks could form 24 hours after coming out of the kiln, but the pattern made the pot look even more exotic.

While I was cooking breakfast the next morning the pot’s handles fell off. By noon the handles were two piles of ceramic pebbles. Throughout the day, I could hear pop, pop, pop, as more tiny shards exploded from the vessel. By noon of the third day after firing, the beautiful two gallon Maya tripod cooking pot was a pile of polychrome pebbles. It was an artistic disaster.

Further research in a book on Britannic-Roman shell-tempered pottery revealed the source of the disaster. Shell-tempered pottery can only be fired to the point when it just begins to glow red. If it is fired the translucent, orange-red glow of stoneware and porcelain ceramics, the calcite changes into an unstable chemical similar to Portland cement. After it cools, the unstable calcium compound will absorb moisture from the air and revert to hydrated lime. At this point, nothing bonds the clay particles together, so they disintegrate.

There were enough crushed, hydrated freshwater mussel shells to make a big batch of pottery, if I mixed them with limestone sand. The chemical reaction was the same for limestone as shells. The new pieces of pottery were fired to just the right temperature. They came out of the kiln perfectly and did not disintegrate afterward. However, making shell-tempered pottery was not worth the effort and risk.

Zuma:
Thanks for all the great replies. folks:)
I happened to be in Florida and the gator pipes
seemed apropos. I actually gifted some pipes and
bowls to folks I met down there before they went
snap crackle pop. I never heard about it :laugh:
BJ Lyman has a darn good handle on all the primitive stuff.
I totally recomend playing with the mud It's rewarding.
Hey I just saw the Alabama death post >:D. Glad you found it
nothing about it on a  on a shell tempered pottery search.
Open flame temps are around 1650 degrees (ABO Earthenware)
Stoneware around 1850-2000. which I use in the kill. (insurance)
and I fire my spaghetti bowls too. Above 2k you can get porcelain

Grog can also be used for heat transfer. Natural sand is not good as it is round
from erosion or glacial action. That's why they crush rock for grog.
The tiny jagged edges knit together with the clay better.
Zuma

Zuma:
Oh Tom I almost forgot. ???
No potatoes for you! :P
Zuma

Tom W:
I had hoped they(the potatoes) were all consumed by now! The ribbed mussel shells I gifted you are a SALT water species. Not sure about the toxic aspect of them vs. fresh water, think Lyman has the correct idea, throw them in the fire and walk away.

Navigation

[0] Message Index

[#] Next page

[*] Previous page