Instamorph is an non-toxic, lightweight polyester thermoplastic which can be heated in hot water and can be moulded like clay to produce many different items. When purchased, Instamorph comes in pellet form and can be poured into hot water (60°C / 140°F) to melt.
Instamorph is also reusable, so you can melt it again to reform into a completely different item from before. However, if you start from a big ball of the plastic, you will quickly find it very hard to heat sufficiently in hot water to melt again.
In this tutorial, I take you through how to heat your big ball of Instamorph in an oven. You will end up with a flat sheet of Instamorph which you can cut into small strips and store back in its original bag to reuse in hot water.
Step 1: You Will Need...
To reform your big ball of Instamorph into small strips, you will need:
- Oven (gas or electric)
- Non-stick baking tray
- Metal utensil eg spoon or pallet knife
- Container to store your Instamorph in
Choosing the oven temperature
Turn your oven on and set it to a low temperature. The Instamorph instructions state to warm it in water of 60°C / 140°F, but this is too low for a conventional oven. I found a low setting was best, but the "keep warm" setting my gas oven has was too cool.
Suggested values for your oven are Gas Mark 2, 150°C or 300°F. While this is significantly hotter than the recommended temperature of the hot water usually used to warm Instamorph; remember that we need the heat to penetrate to the centre of a big ball of the plastic and warm that to at least 60°C / 140°F.
Step 2: Put the Ball in the Oven and Frequently Check It
Place the ball of Instamorph on a non-stick baking tray and place in the preheated oven.
Keep an eye on it through the oven window. After the first 10 minutes, take it out to see how it's getting along. By now, the outside of the ball will be beginning to melt and go transparent. You should be able to use a metal spoon or pallet knife to flatten the transparent outsides of the ball.
This will allow the heat to penetrate the solid centre of the ball much quicker.
WARNINGS: The Instamorph will be very hot, so use a utensil to flatten it.
If you use a non stick-tray, make sure not to scratch it with your metal utensil. There's a chance that a wooden or plastic utensil will stick to the Instamorph. I managed to use the non-stick tray and a metal spoon without damaging the non stick surface of the tray.
Step 3: Continue Until You Have a Flat Sheet
Continue heating and flattening your Instamorph until you have a thin flat sheet. My ball took 40 minutes to get to this state.
Towards the end, when your Instamorph is almost in shape, it is very easy to boil it. You can see that happened in my photos above, where the flat surface is now covered in small holes.
You should be able to avoid that happening by turning off the oven but keeping the door closed so the heat is retained. You need to keep a close eye on it too; not much time is needed in the oven when you've just flattened it into the final shape; just a few minutes to get a nice smooth surface.
Take the tray out of the oven and allow the Instamorph to cool to a temperature you're comfortable to touch. This should only be 2 - 5 minutes cooling, depending on the size and heat used. Don't wait for the Instamorph to be completely cool!
Step 4: Cut the Sheet Into Small Squares
Once you're happy handling the Instamorph you can now use your flat sheet for your new project.
If you want to store the Instamorph for another day cut it into strips, then cut the strips into squares. Once cold, your Instamorph is ready to be poured back into it's original bag or a new box and stored until you want to use it again. You can now follow the instructions on the packet and heat the Instasmorph using the hot water method.