Author: Midushi Kochhar
Preparation of eggshells:
Collect as many eggshells as you need from your home, neighbours, cafes, etc.
This version of the recipe uses 20 grams of eggshells.
Wash the eggshells thoroughly and boil them for about 15 mins to kill all bacteria.
To dry the eggshell, you can use one of these two methods:
1. Place the eggshells in the oven at 100 degrees for 15 minutes.
2. Place the eggshells in the microwave for 1 minute at high temperature, then 3 minutes at med-high.
Both methods work, but the eggshells need to be dried out; brittle but not burnt. Subtle crackling sound means that the eggshells are ready.
In a blender, grind the eggshells down to the tiniest particles possible and pass the powder through a sieve. Try to achieve the finest powder.
(If you don't have a blender, you can use a pestle and mortar an grind the eggsells by hand.)
PLEASE NOTE - The following steps need to be completed within 3 minutes, before the alginate starts to cure.
Mix all the ingredients together:
First sieve the 5 grams of alginate in a mixing bowl. Add 22ml of water to the bowl and mix thoroughly so that no lumps remain.
Gradually add the 20 grams of eggshells into the water-alginate mixture until a thick slurry* is formed and all the ingredients are mixed well.
*Slurry is a semi-liquid mixture, typically of fine particles suspended in water.
Pour the mixture into a mould. You might need to use a spoon to transfer all of the material mixture.
Let the composite dry and do not touch. Depending on the thickness of the sample, the drying time can vary. Drying options as follows:
OVEN: At 50° with fan for 5 mins. Check and repeat as per requirements as all ovens are slightly different.
AIR DRY: Can take 24 hrs+
After drying, the size pf the composite test will reduce by about 7%. Increase the ingredient amount in the same proportion to fit your requirements.