Make a Clay Damp Box for less than $20!

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I'm a mom of two young children. Finding time to work on my pottery is tough. These damp boxes keep my pots leather hard for months at a time if needed! I used 50 pounds of plaster (about $18) and 2 plastic totes ($9 each) to make two damp boxes. This was enough for a 3'' slab of plaster in the bottom of my totes. I probably could have gotten away with half as much because the totes are sooo HEAVY now. You can add water as needed to the plaster to create a humid environment to keep your clay moist.

Materials: plastic totes, water, pottery plaster, scale, drill to mix with

1.) Figure out how much water you need. For USG pottery plaster #1, the ration is 70 parts water to 100 parts plaster.  For 25 pounds of plaster, you need 2.25 gallons of water. The water should be room temperature.

Here's a great chart from Ceramic Arts Daily:

2.) Weigh your plaster.

3.) Slowly add the plaster to the water while mixing. I mixed the plaster right in the the totes, but you can mix it in a separate container also.

4.) Continue mixing until all of the chunks are gone.

5.) Allow about 24 hours for the plaster to sit up. Clean up the sides with a sponge and use a shop vac to get rid of any plaster crumbs. Start using your damp box!


  1. I use a similar process, but instead of plaster I place a piece of sponge rubber at the bottom of the box. Pour water into the box until the sponge will absorb no more and cover it with rigid plastic sheet (Correx or similar). If you wish a little Milton solution can be incorporated to keep mould away, but this is not essential. I use the same system to store clay.


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