WHAT TO DO
Mix water, liquid glucose, sugar, and cream of tartar in the pot. Stir often and slowly bring it to a boil. If you boil it too quickly, it'll caramelise. As it heats up, it'll go from a cloudy colour to clear.
Heat the mixture to 150°C, then remove from heat. This should take at least an hour. Use a candy thermometer, but be careful not to let it fall in the mixture. You’ll know it’s ready when half of the mixture has boiled away and the molten sugar forms strings when it drips off the spoon.
Spray the baking tray generously with cooking spray or line it with tin foil.
Put on the thick gloves and pour the hot mixture very carefully onto the backing tray. Pour slowly to minimise bubbles.
Place the baking tray on an even surface. This will help the mixture spread out evenly so that the finished glass isn't thicker in some areas and thinner in others. Leave the mixture to dry for about an hour. After 45 minutes it should be cool enough to touch, but it isn't hardened, so don't take it out until the full hour has passed.
To remove the dry glass from the baking tray, take a knife and heat it up under hot water, then carefully cut along the edge where the glass meets the edge of the pan. Carefully pry it up, flip it over and slowly lift the pan away from the sugar glass that is resting on your hand.
Make coloured 'glass' by adding food colouring.