Clay pliability / short aging time.

[firebob]

I mix all my own clay's.  My stoneware I like to age 6+ months and my terracotta I like to age 3+ months.  Somehow (dealing my illness) I only mixed around a third of the terracotta that I normal do.

What I like to do... Is mix the clay, pug mill, store / age, than us a de airing pug mill right before I use it.

I have around 3 tons (dry weight) of terracotta that was mixed, pug mill, aged about 3 weeks, re pug mill, aged a week, and have not messed with it.

Is it worth cleaning my de airing pug mill and trying the terracotta, or will it need to age longer?

Would it be better to pug mill it Monday and let it sit 1 more week before starting on it?

The largest pot I would make with the clay would be 40 pounds.

Thanks for the suggestions.

[neilestrick]

I don't find any need to age if it goes through a de-airing pug mill, especially if you're using some slurry/reclaim in the mix.

[Mark C.]

I agree with Neil as long as you have some old slurry or slop or reclaim in the mix as he noted.

The old stuff really lacks a difference  even if it just a small part of the mix.

[firebob]

It was all made fresh.  I only throw terracotta during the winter.  I only buy terracotta once a year.  It's much cheaper to fire in the gas kiln when the cost of propane is up.

I did wedge some up today and play with it as I was firing both my kilns and think it's a little iffy for larger pots.  I ran it all back through my big pug mill and cleaned everything up to switch back over to terracotta in the morning.  It'll get the de airing pug mill right before use.  It should improve over the next week I hope.

[glazenerd]

Bob:

Welcome to the forums. In reviewing the information in your posts; needed information is missing. Your comments suggests that you are buying dry premix clay bodies, in lieu of custom mixing your own recipes? I do not see a cone fire listed. Giving the length of time you are aging your clay after mixing, suggests something is amiss somewhere. I know some potters like to age their clay; so it will become either softer or stiffer pending preference. 

I will "assume" you are mixing in a drum mixer, or some other non de-airing mixer; letting it age for a period: then running back through a vacuum pugger? Even if you mix in a Soldner or similar mixer; after a week plasticity should be achieved. Pending particle sizes, aging might be beneficial: perhaps a few weeks tops. 

So when you say check it and it is not there yet, raises my eyebrows after months of aging. It makes me wonder if you are mixing a sculptural body, which has little to no plastic materials. I could understand the aging if this were the case; more so for terra cotta. Stoneware however usually has higher % of plastic clays in the recipe. However, like terra cotta there are recipes for specific uses that would have little plastic materials. Something in this process is off; just trying to figure out what it is. Which by the way is not a comment on your methodology, but rather I am highly suspicious of the recipes. I understand you have a preference in firmness; which could also be controlled by water content or open drying time before bagging.

nerd

[firebob]

I buy all dry clay.  My stonewear recipe is from my dad, but my terracotta is a normal mix.

I mix in a Soldner, the a large self feeding pug mill, cut the clay into logs and put into a plastic tote / pallet that doubled bagged, and stacked to age.  I use a de airing pug mill before I use the clay.

I have found it's hard for me to throw a terracotta pot that has a 20" rim or a large strawberry pot unless the clay has aged.  It could have some to do with me taking the clay out of the de airing pug mill and going to the wheel with out wedging and how I learned to throw.

I know very little when it comes to clay chemistry. 

[glazenerd]

Bob:

You know more about clay than you think: you mix your own. The aging is to achieve firmness, from what I am gathering. You can achieve firmness by a change in particle sizes, % of clay content, large particle additions, and water content. Bottom line, there are easier ways to slay the firmness beast 

here is a simple test for both bodies.

100 grams of terra cotta mix. Mixed with 24 grams of water. Mix in a bowl or other non- absorptive surface.  After mixing thoroughly: wrap in cling wrap ( food wrap) and let it stand one week. Do exactly the same for the stoneware.

Open one week later:  if tacky or sticky: ball clay content is too high, which makes for a  weaker body. Which also means water content is too high. 2. If it is dry and cracks easily, could mean several things. If silica and feldspar levels are high: that will diminish plasticity. More likely that ball clay content is too low.

you can make additions to both bodies that will make them stiffer, and will support larger forms. At this point, given your mixing protocols, and aging process: water content is too high.

[firebob]

Next time I mix clay I will give this a try.  Thanks