In this step by step tutorial I'll show you how to make your own plastic products out of waste you normally throw away or hopefully recycle, mainly plastic items such as milk jugs, plastic bottle caps and bleach bottles. I will be making hexagonal tiles that could be mass produced to decorate bathroom walls but I've also found they make for good coasters...
Step 1: Collecting Your Plastic
The plastic you're going to be using for this upcycling project is High-Density Polyethylene (HDPE) and Polypropylene (PP). To find these types look on your plastic waste for a symbol showing three arrows in a triangle with a number in the center. You're looking for the numbers 2 for HDPE and 5 for PP. Cut them up into small pieces ready for melting, don't worry about mixing the two types as they have very similar melting points and wont interfere with each other.
Step 2: The Mould
You're going to want something to press your hot plastic into. For my tiles/coasters I used a mould i made out of MDF that had been laser cut into the desired size and shape. I glued on a base and a handle leaving me with a simple mould that can shape the plastic easily when the lid is clamped down into it. The mould was then lined with grease proof paper to stop the plastic sticking to the wood. You don't need a fancy laser cutter to make your own mould. You can use anything you like as long as it will hold under the pressure and heat but the idea for my project was to make these moulds and sell them on for people to use with their own collected plastic, in turn this would hopefully reduce our plastic waste in the world.
Step 3: Melting the Plastic
Now it's time to melt down your collected and cut up plastic, the best option is to use the oven at 170C/340F until the plastic is tacky and pliable. I used a heat gun because it's faster but not as safe because over 180C gives the risk of toxic fumes coming from the melted plastic. You have to be quick with the next step, get some heat resistant gloves ready. I learnt the hard way that you need gloves to handle hot plastic.
Step 4: Press the Plastic
Once your plastic is hot and malleable its time to put it into the mould. Be careful when transferring it over because it will be too hot to touch with bare skin. Now that the plastic is in make sure its even and close to the corners, it doesn't have to be perfect because the clamp will do the rest. Lay a sheet of grease proof on top then press the lid on. Apply a clamp and tighten until you can't anymore.
Step 5: You're Finished Piece
Leave your mould to cool for an hour or more depending on how big the plastic item is. There should be a slight amount of shrinkage during the cooling because hot plastic will contract as it gets colder. Take off the clamp and lid and you should be able to remove the plastic easily. As you can see mine came out pretty nicely but sometimes you may need to sand it down or remelt with added plastic if there are areas missing. You can use certain colours and shape the plastic to give it cool effects too. I hope to make some like that and show them in future projects.