Casting with Plaster

A sheet of aluminum foil with cardboard underneath it is on one side of the picture. The image of the engraving to be copied is visible in the foil. A can of shaving cream is in the background; the shaving cream was used to attach the aluminum foil; to the cardboard for stability. The finished plaster cast, with its tactile design is next to the aluminum foil and cardboard.

Target Subject: Technology/engineering

Author

Adapted by Yoo Jin Chung and Kate Fraser

Purpose

To provide students with hands-on experience with various tools and materials used in design and construction. The student will make a mold and a duplicate for an engraved image.

Background Information

Buildings and monuments often have engraved writing or interesting designs. A student with a visual impairment may not notice these features unless given the opportunity to examine them. On a field trip students may tactually examine various possibilities. Be sure to get permission from the owner or management of any private property.

Preparation

Assistance and/or pre-teaching may be needed with using scissors, and making the plaster.

Materials

aluminum foil, scissors, tape, shaving cream, heavy-duty cardboard or lightweight wooden panel, plaster

Procedure

1. Find an engraved image to make a mold of.
2. Cut out a piece of aluminum foil. When cutting, make sure the foil is big enough to provide 3 to 4 inches of border around the image.
3. Place the foil on the image, so that the foil covers the image completely. Slowly and carefully, push the foil over the image with your fingers. Make sure you don’t tear the foil. If you tear the foil, start over and try again.
4. With the foil still on the engraving, thoroughly cover the foil with shaving cream. The shaving cream will act like a glue to hold your mold in place. Quickly, place the cardboard over the shaving cream. Slowly and carefully, pull back the cardboard to separate the engraving and the foil. With the aluminum foil facing up, place the cardboard piece on the ground.
5. Fold the edges of foil up to create sides of the mold. Tape the sides to make sure the sides stay together. The mold is now complete!
6. Mix the plaster according to directions. Make sure there’s enough plaster mix to cover the foil mold. Work quickly! The plaster hardens very fast.
7. Carefully pour the plaster into the foil mold. Gently shake the cardboard as you pour to prevent air bubbles from forming.
8. After the plaster casting hardens (the plaster gets warm as it hardens, then cools when it’s done), peel away the aluminum foil.
9. The foil mold can only be used once. Your complete casting will be hard, smooth and an exact duplicate of the original engraving!

Resources

Pierce, Alan J. and Dennis Karwatka. Introduction to Technology, Third Edition, The McGraw Hill Companies, 2005, pages 102-103