What you need:
3 plastic containers (casting+alginate mixture+plaster mixture), spatula, modelling paste, cutter, sandpaper.
Instruction:
1. Stick the abject to be moulded at the bottom of the plastic cup with a small piece of modelling paste. Make sure that the object does not touch the walls. In a recipient, pour a volume of alginate, i.e. half the casing. Pour onto the powder two volumes of water and mix vigorously for one minute. Do not worry if any lumps farm, since this will not affect the quality of your mould. Pour the mixture on the object.
2. Wait 50 to 10 min. until the mixture has set: it remains flexible but should be set like jelly. Slide a knife between the wall of the glass and the mould to allow air to enter. Take the alginate mould out of its casting and remove the piece of modelling paste from the bottom. Using a cutter, cut the alginate mould longitudinally, making sure that you do not damage the object.
3. Pierce the bottom of the plastic cup with the cutter. Put the two halves of the mould back together in the casing. Turn over the plastic cup with the holed bottom towards you. Prepare the plaster, then pour in into the mould through the opening created by the modelling paste. Wait half an hour until the plaster is dry, then once again take the alginate mould out of its casing. Separate the two halves and extract the plaster casting. Smooth it lightly with sandpaper if necessary. You can use the same mould for a maximum of 3 castings.
Gedeo tips:
- Before using the powdered alginate, pour it into a sealed container and shake vigorously. The aerated powder will not form lumps.
- The alginate sets more quickly with hot water, and more slowly with cold water.
- You can also make a casting by embossing. Slightly reduce the amount of water, and apply the mixture onto the subject when it has started to thicken.
- How to make a mould to measure: Cut out a semi-rigid strip of plastic film to the height required and form a cylinder. Fasten it with adhesive tape. Place this cylinder on a smooth surface and seal the join with modelling paste.
