The Damp Box
Why and How to Make Your Own
Making pots takes time. Decorating them takes even more in some cases. One thing that is always at the forefront of a potter's mind is the moisture state of the piece. If it's too dry, the carving tool will leave ragged edges. If it's too wet, the clay will stick to the tool and smear. Timing that handle attachment or that mishima scraping is a major part of our art that takes practice and patience to perfect. Let's face it, though: we all have busy lives, and sometimes, time constraints don't allow us to wait for just the right moment. Luckily, there is an easy solution that makes a great addition to your studio: a damp box.
A damp box is a humid container in which to store in-progress claywork. You are creating a makeshift version of this every time you put a plastic bag over an incomplete piece. The advantange of a damp box is that you can do this without the hassle of the plastic bag, or the potential surface marring it can cause.
Now, you could pay hundreds (or even thousands) of dollars for a fancy damp cabinet from a manufacturer, but I'm a broke twenty-something who pinches every penny until they beg for mercy. Why pay all that money for something you can achieve with $20 and 30 minutes of your time?
Once you have chosen your box, you will need some plaster. I prefer a medium-density plaster such as Puritan Pottery plaster or #1 Casting plaster (both are available at Armadillo Clay). You will want to weigh out about 10 lbs of plaster for a 30-40 gallon box. Smaller boxes will use less plaster. Assuming you are using one of the two plaster choices I recommended, you will need about 6 1/2 pints of water to make up that 10 lbs of dry plaster. In a clean bucket, measure out your water, then add in the dry plaster and mix for about 5 minutes. Make sure to wear a respirator! Once your plaster is well-mixed, carefully pour it into your box until you have about an inch depth of plaster in the bottom. Too much, and the box will be very heavy. Too little, and your plaster layer will be prone to breaking when you move the box around. Let the plaster set overnight, lid off.
Your damp box is ready to use! Make sure to leave the lid off when it is not in use, to avoid mold growth. If you do get some mold growing, you can spray the plaster slab with a bit of well-diluted bleach. To recharge your damp box, just pour some fresh water onto the plaster slab. I prefer to have a layer between the plaster and my pots, so I cut some old Orton Cone box liners to make a soft sponge layer on top of the plaster. Once you have a damp box, you'll wonder why you didn't make one years ago!
10/5/2018 11:51:59 am
Can you mix up the plaster right in the container you are planning to use? Otherwise I don’t have a throw-away for mixing.
9/8/2020 01:28:33 pm
You will need a separate container to mix the plaster.
3/24/2020 07:19:00 am
Thank you so much for sharing this!!!
9/7/2020 04:24:49 pm
So, you never actually tell us how much water to put on the plaster; only to recharge it by adding more. Do we cover the plaster layer in water? Thanks.
9/8/2020 01:38:03 pm
The amount it takes to recharge the plaster in the box will depend on how large/thick the plaster slab is, as well as if there is any moisture still in the plaster already. Best approach would be to add water a cup at a time and continue adding until the plaster becomes slow to absorb the water (about 10 seconds for the cup of water to disappear). You don't want your pots sitting in water, so only add enough to saturate the plaster. If you add too much, you can carefully tip the box to pour out the extra.
10/27/2020 08:41:27 am
I have made these for years for our class out of Sterilite gasket clear plastic boxes. The gasket keeps them air tight and the clay stays workable for years. We keep just enough water in them to see water droplets form on the lid. I don’t premix the plaster in a bucket. Just pour plaster in the storage container, add water according to the directions, stir and shake the box so the plaster levels out. If any droplets splash onto the sides of the box, just wipe away with a wet paper towel. I use DAP plaster of Paris. It finishes smooth and free of bubbles. Don’t know about other plaster products.
5/27/2021 04:52:23 am
8/12/2021 08:18:07 pm
I recently made a damp box with a large container
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