[Clayart] humidity

[John Rodgers]

Interesting ways to dry clay that we all face. I once had a really big
order - 800 each chalices and patens - and just so much time. The trick was
how to save drying time or I might miss my deadline. Solution? It was
summer, very hot. I got a shipping container, put some very open racks
with open bottoms inside. Added four large fans to stir the air yet not
blow directly on the clay. Added a big dehumidifier with a hose going
outside.  With doors closed, the heat in there combined with the
circulating air and water extraction by the dehumidifier did the trick. I
had a constant stream of pottery going in and out of that setup. Pottery
put in there in the morning was completely  dry and ready to bisque fire by
the end of the day. Never had any cracking, or warping. Worked great.

On Tue, Mar 7, 2023 at 1:33 PM Sharon Cary <scarythepotter at gmail.com> wrote:

> I discovered years ago that my small pieces, covered with pieces of cotton
> sheets, would dry nicely and relatively faster than under plastic. If they
> need additional work, a sheet of plastic Over the cloth would keep them
> leather hard until time to trim. The salt shakers I make are by nature
> thicker at the bottom and would develop stress cracks if left uncovered,
> but just keeping the drafts off with cloth solved that and let them dry.
> Small slab plates don’t warp when covered this way as well.
>
> S.Cary -
> Make something beautiful every day.
> Sent from my iPad
>
> > On Mar 7, 2023, at 8:15 AM, Snail Scott <claywork at flying-snail.com>
> wrote:
> >
> >
> >> On Mar 7, 2023, at 6:48 AM, mel jacobson <melpots at mail.com> wrote:
> >> In many ways sheet plastic wrapped around sculptures has the opposite
> affect.
> >> The water migrates to the plastic like a rain forest and drips back
> onto the
> >> piece….I met an amazing sculptor...She wrapped her sculptures in
> linen...
> >
> >
> > Yes. Plastic is, in my mind, the biggest game-changer in the history of
> ceramics since the kiln. Gas, electricity, cones, frits…all that is just
> modifications and upgrades.  Plastic makes keeping clay wet incredibly
> easy. When Rodin travelled around France, schmoozing the collectors, he
> left poor Camille Claudel back in the studio to wet down the rags every
> day,  keeping the work-in-progress workable until he returned. Imagine what
> she could have accomplished with a box of trash bags and some free time!
> >
> > However, plastic is not good for keeping the moisture even, and does not
> allow clay to dry evenly, either. When sealed up and kept tight to the
> clay, thick plastic holds moisture in for quite a while. When loosely
> draped, though, condensation gathers at the top during overnight chill. It
> drips down onto the top, and runs in rivulets to puddle in the bottom…the
> bigger the work, the bigger the issue. When people want to start drying the
> work, they tend to drape the plastic loosely, with gaps which cause uneven
> evaporation.
> >
> > I cover work in progress with thick cotton sweatshirt fabric or cotton
> towels under the plastic.  When I want the clay to be softer, I spray the
> cloth with water, dampening it and creating a humidifier inside the plastic
> environment. The cloth wicks the moisture evenly, and it catches and
> redistributes condensation. (For serious rehydration, direct contact with
> damp cloth is the way to go, though…water is held against the clay and does
> not run off into a puddle. like sprayed water does.)  When I want the clay
> to stiffen, I swap the cloth once or twice daily for dry cloth, removing
> just the moisture that had absorbed from the atmosphere inside the plastic.
> The cloth does not need contact with the clay to do any of this…it affects
> the humidity under the plastic, not the clay directly.  The more cloth, the
> greater the effect, both for dampening and dehydrating. When the entire
> piece has reached the stiff leather-hard phase, beginning to turn pale, I
> remove the plastic and wrap it in just cloth. It permits evaporation, but
> slower and more evenly than open air exposure, with no drafts. I have
> refined this over many years, and it works. Cloth inside plastic is a
> portable damp box; and folds flat when not in use! Stacking bins are great
> for small pots, but not for larger work.
> >
> > It frustrates me to see people covering work well in plastic and
> wondering why it won’t dry, or draping plastic with big gaps at the side.
> creating dry spots and irregular shrinkage. Perforated plastic is better,
> but it can’t move the moisture like cloth can. Drying ’slow’ is not the
> goal; drying evenly is.
> >
> > -Snail Scott
> >
> >
> >
>
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