Casting Plaster Alice 10c

In this instructable I will be showing how to make a paperweight out of plaster with just a few steps. Before we get started make sure that you don't have any food or open drinks around as you don't plaster dust in your food, all surfaces should be covered to avoid them getting dirty, wear an apron to keep your clothes as clean as possible, if you have long hair tie it up and while cleaning up avoid pouring plaster in the sink as it will result in clogged pipes.

Plaster, Polypropylene, Cardboard, Scissors, Water, Tape, Ruler, and Pencil

The first step to making a successful polypropylene mold is to experiment with paper, make sure the mold is stable to hold plaster, keep in mind that the paperweight has to be a certain size to weigh down the paper. Do not attempt to pour plaster into the cardboard. Try taping the cardboard net together to see if all the sides align. Once you're happy with your design you can continue to your next step

Take your net design from Step 1 and trace it on to the polypropylene. Be careful not to damage any of the pieces that you want to use later on as this could lead to leakage. Once you're done cutting out your net seal all the edges with tape, make sure everything is very secure. Avoid using tape on the inside of your mold, this could leave ugly marks on your final paper mold which we want to avoid.

To prepare for pouring the mold cover your working space, wear an apron, and tie up your hair if needed. The ratio to make the plaster is 2:3, 2 cups of water and three cups of plaster powder, while making the plaster you might need to add more powder or water depending on your mixture. To avoid lumps in the mixture add the water first into a big container and slowly stir in the plaster powder, make sure the mixture is thick but also still pourable. Before pouring in the plaster mixture you can place things into the mold like rhinestones or letters as shown in the photos above. You can also add color to your plaster as plaster is usually grey, I recommend using watercolors because they blend very well with the plaster mixture. Now take your polypropylene mold and slowly pour the plaster in, try to avoid pouring it over the edges. Set the mold aside to dry and start cleaning up. When cleaning all the utensils used try scraping everything off into the trash, paper towels are very ideal for this situation. do not wash off your utensils in the sink as this will clog your pipes.

After waiting a reasonable amount of time your cast is ready to be removed. You can use an exactor knife for this step ( please ask an adult for help) to cut the polypropylene, this might not be needed depending on your net shape. Be very careful while doing this step to not cut into your paperweight. You might need to clean up your design with some sandpaper to make it look the way you wish, this is very common as the plaster can stretch out the mold at times or leak from small mistakes.