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Humidity and greenware drying


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I am rather new to pottery, and my classes have been canceled to us with hands on classes in CA. 

I have a question on drying greenware, in a humid area. 

I am considering a movie to Mazatlan, Mexico and the humidity is 70% often, where as CA is 12% often. What do you do to dry your greenware slowly, yet with a complete dry?

It seems to be a challenge. 

Please advise. 

Thank you, TeaPotter

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Certainly takes longer and can be supplemented in a lightly heated enclosure (light bulb is common) but...... it will likely need a bit of drying in the kiln regardless. Traditionally bisque cycles in high humidity areas call for a drying segment or preheat very slowly to about 250 degrees to help the situation.

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I have humid summers where I live. It’s been around 60% for the last week. Even when it’s humid, as long as the air in the studio is moving, pots will dry. So I keep a fan running all night. As soon as I have enough dry pots to fill a bisque kiln, I roll my drying rack over near the kilns. The draft created by the vent hood, plus the heat from the kiln, does a quick job of drying the remaining pots. 

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10 hours ago, Bill Kielb said:

Fans work, but we always caution their use in a studio for dust reasons

Are you also recommending that pottery studios should not use air conditioning? It seems like the same thing in terms of creating a draft. In the summer, I run a portable AC when I’m in the studio working. When it’s very humid, I run a fan at night to help the pots dry. I don’t think I could be productive in the summer without either of them. If it’s dangerous, then it’s a trade off I’m willing to make. 

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AC does pull some some moisture, which is almost always helpful...

fwiw, I'm no longer using fans (in the studio), as the air stream is more focused, hence kicks up more dust; there just isn't a place to point it where the air wash doesn't reach places that I'm not willing to clean regularly (behind material stores, under shelves ...my studio, err, studio/workshop/bike shop, is in a one car garage - not particularly large). I open the rollup door and the person door to get gentle air movement, which is almost always enough to speed drying, and kicks up less dust. When in a hurry (doesn't happen very often, heh), I'll carry ware boards outside.

Also fwiw, I'm "monitoring" dust levels via accumulation on horizontal surfaces about the studio - how much dust, where, how long, etc. I'm seeing that keeping the floors clean makes a big difference - stepping on dry clay makes dust - however, the biggest culprit appears to be the wedging area, where opening/closing clay bags that have any dry clay on the plastic and allowing any clay to dry on/around the wedging boards generates dust. Any cloth - rags, clothing (not much difference, heh) - that gets clay on it will generate dust. Looks like greenware sheds dust, however, storing it away from breezes seems to help.

Point being, how to monitor dust levels? I don't know, other than watching the surfaces about the studio. I placed a clean bat out of reach at the local JC ceramic studio when I was taking classes there, and was appalled (but not surprised) how much filth built up in two days. Well, this (post) isn't the first time I've made a case for monitoring dust... 

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1 hour ago, GEP said:

Are you also recommending that pottery studios should not use air conditioning

Just caution with fans.

Ac equipment is filtered so there is that but as a recommendation better filters would be great and part of a  thoughtful design. 

In many studios fans are forbidden because they blow dust around. It’s good practice, they are nearly always higher velocity than any AC discharge so that compounds the potential problem with fan use as well as folks using fans generally blow it right on the clay. 

Sweeping just never is as good as sweeping with compound which is still much worse than wet mopping. Just reasonable caution is the message, things that spread dust - do.

Best idea I saw for drying is low temp warming plates set up for just such use instead of folks piling their wares on the edge of a kiln. For High humidity areas, some form of passive  heating is probably most effective.

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I’d bet there is a big difference between studios that have dozens of users, and studios with only one user, in terms of how much dust is around. 

I sometimes put pots on top of a warm kiln to dry them faster too. But I don’t think it makes sense to turn on an additional heat generating device in the summer. 

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A forced air system in the house will negate that 70% right quick. I don't use AC and have radiators. Huge difference as well. Education from plants. Transferred to Clay.

Understanding and abiding by an appropriate Kiln Cycle is the prevention of this problem.

Work a month or 2 ahead of the game. 

Don't be like "Sally Steam Explosion" and burn yourself, both literally and figuratively, trying to take hot wares to a plastic booth table.

I don't believe in drying "slowly" or "evenly". 

Dry APPROPRIATELY.

Weigh em, when they stop losing weight for X amount of days, they are ready.

A pot can not lose water at 100% Humidity.

Humidity determines X.

All you need is a longer kiln cycle and more prefire storage shelving.

Sorce

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19 hours ago, Bill Kielb said:

Just a quick caution
Fans work, but we always caution their use in a studio for dust reasons as well as sweeping vs. wet mopping.

I'm really fortunate to have my studio mostly outside because of where I live.  Air flow is my dust control.  If you live where the climate is not so hospitable,  artificially controlling dust, temperature, humidity is considerably more difficult, I'm sure.

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15 hours ago, GEP said:

But I don’t think it makes sense to turn on an additional heat generating device in the summer. 

Maybe, but watts of fan or watts of hot plate all says same energy. One spreads dust and heat and one just locally heats the pots. I have watched  folks just put an old forty watt lightbulb in their lightly covered (plastic) drying area and turn on for the day.  Lots of room for the lamp not touching anything and it got  the space At least 10 degrees warmer to aid in drying.

Typical 12 inch oscillating fan = 50 watts which adds  50 X3.41 =170 Btuh plus lots of moving air, 40 watt light bulb  = 40w X 3.41 = 126 Btuh and much less dust blowing. I think the light bulb was a cool idea so to speak.

Edited by Bill Kielb
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It’s not about energy use, Bill. It’s about not wanting to make the studio hotter when the weather is already hot, and when there are hot kilns to deal with sometimes already. The energy use difference between a light bulb and a fan is made insignificant by the kilns. I’ll take the option that actually makes the studio cooler.

Edited by GEP
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4 hours ago, GEP said:

t’s not about energy use, Bill. It’s about not wanting to make the studio hotter when the weather is already hot

No worries I understand. Since watts are energy though the fan is actually adding more heat To the studio than the light bulb. 44 btu per hour I believe. The energy has to go somewhere. I am quite against fans in the studio but realize many folks do use them.

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