Translations:AY Honors/Plaster Craft/Answer Key/24/en

Preparing the mold

Plastic molds generally cannot support themselves once they are filled with wet plaster, so you must prepare a support base to set them on. This support base can be as simple as a sealable plastic bag filled with uncooked rice or sand. Squeeze as much air out of the bag as you can, and then lay the bag flat on the work surface. Place the mold on top of it and press it into the support, wiggling it around until the support conforms to the shape of the mold. Try to get the mold as level as possible. Once the mold is in place and well supported, coat the mold with mold spray (see requirement 3).

Mixing the plaster

The most fool proof way to mix dry plaster powder with water is to weigh them. Use seven parts plaster to 10 parts water by weight. If you know how much your plaster weighs, multiply that weight by 1.43 to get the required weight of the water. It's a lot easier to do this using the metric system, because a milliliter of water weighs one gram. So if you know how many grams of water you need, that's also the number of milliliters of water you need. Let's run through an example: