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Hempcrete Stool [Assembly]
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1 Cut a piece of cardboard 18.5in x 44in (47cm x 112cm) so that the corrugated lines run along the 18.5in (47cm) side. Roll up the cardboard to create a cylindrical form.
2 Tape the cardboard together, forming a cylinder. Also tape the cylinder to a wooden board (or anything sturdy you don’t mind getting messy).
3 Use your disposable cup to add 1/2 cup of portland cement, and 1.5 cups of hydrated lime (or 1 cup of metakaolin and 1 cup of hydrated lime) to the mixing bucket. Make sure not to inhale any dust from these materials.
4 Use your disposable cup to add 2 cups of water to the mixing bucket.
5 Use your disposable cup to add 7 cups of hemp hurd to the mixing bucket.
6 Wearing protective gloves, mix everything together in the mixing bucket.
7 Transfer the mix to the cardboard cylinder and press relatively firmly, filling the bottom of the cylinder. The cylinder will be hard to move when all steps are complete, so make sure it is in a location you are ok with it staying for weeks.
8 Repeat steps 3-7 multiple times, until the cylinder is about 1/3 full.
9 Place a smaller cardboard cylinder, about 6in (16cm) in diameter, in the center of the larger one.
10 Repeat steps 3-7 multiple times, filling the gap between the smaller cylinder and the larger one.
11 Fill the cylinder almost to the top. The last mix you make, use slightly less hemp (6 or 6.5 cups). Pat down the mix so that it is perfectly level all around the cylinder.
12 Let everything dry for 2 days, and remove the cardboard cylinders very gently. Then Let the stool dry for about 6 weeks. Over that time, the hemp dries out, and the lime slowly hardens by absorbing carbon from the air.
13 Boil some water in a saucepan and mix in some all purpose flour, making a thin papier-mâché paste. Wait for the mix to cool, and brush it all over the stool. It should dry clear and help keep the hemp from flaking off.