Introduction: Introduction to Pouring Plaster
In this instructable i will be showing how to make a flower pot out of plaster.Before you work with plaster you should make sure that: if you have long hair it is tied up,you're wearing an apron so you don't get your clothes wet,don't dispose of plaster in the sink as it will clog it,cover the surface you're working on so it doesn't get dirty and don't have any food or open drinks around plaster if you don't want plaster dust in your food.
Cardboard,scissors,tape,polypropylene,water,plaster,ruler and pencil
Step 1: Paper Mold
Before starting to work with polypropylene you should experiment with paper molding to make sure your ideas could even work as molds.DO NOT try pouring plaster into your cardboard mold as it will get really messy and you wont be able to take it out of the mold.Use pencil and ruler to draw out your net and cut it out with either scissors or an exactor knife then tape it together and don't forget to make a core.Try making a few molds of different ideas so you have multiple designs to choose from.
Step 2: Polypropylene Mold
After you've decided on a final design and made it out of cardboard do the same but out of polypropylene. You can score the polypropylene very lightly in order to bend it but be careful not to cut the polypropylene instead.
Step 3: Pouring Your Plaster
After you've finished your polypropylene mold you can pour your plaster in the mold.Cover the surface you're working on with something that you don't mind getting dirty.To make the plaster add two cups (I used small yogurt cups) of water and three cups of plaster powder, pour in the water first to avoid lumps.If you think you need more or less plaster mixture you can make however much you need following the same ratio.Mix your plaster mixture until you think its ready, make sure its not too liquid and not too hard before pouring it in. Make sure there are no holes and/or openings in your mold and everything is taped shut in order for the mold to work.Try avoiding using tape on the inside (or outside of the core) wherever the plaster could be touching it as it will be difficult to remove from the hardened plaster.When cleaning the bowl you mixed plaster in avoid washing it in the sink as the plaster will harden and clog the sink.Wait for the mixture to dry in the bowl and scrape it into a trash can.Your shape might take a few hours to dry depending on how big it is.
Step 4: Taking Out Your Cast
After you've waited a sufficient time for your plaster to dry (depending on the size of your shape).Take it out very carefully, you will probably need to use an exactor knife to cut the polypropylene as its very hard to take the plaster out without any help. Be very careful so you don't ruin your net as you might have to have another go at casting if it didn't turn out exactly as you wanted.After your plaster is free you can try sanding the edges or the inside to make them perfect and you're done!If you arent satisfied with your result try taping the net back together and have another go at casting but keep in consideration what exactly you want to change and/or do better in your next shape.