HDPE is one of the most common and versatile plastic materials found in a wide range of home items and appliances—and it’s the perfect material to use for some DIY projects! Milk jugs and bottle tops are almost always made from HDPE, so if you start collecting these items today, you will be able to create some functional and ornamental products to start using around the home.
 
What’s so great about using HDPE is that it helps you minimise waste too. There’s no need to throw out all that plastic packaging when you can store it, cut it up, and then melt it to create some great crafts at home.
 
In our three-part series that we hope will inspire some fun school holiday projects, we previously looked at the everyday home items that are made from HDPE and you can collect and reuse.
 
In this guide, we are going to cover the basics of how you can melt milk bottle tops to create your sheets of recycled HDPE. These blocks of HDPE can then be cut to any size and shape, melted down again, reformed, and used to make anything from bowls to custom pens and more!
 
We would recommend using an old sandwich press, like the one used in our examples, as this will never heat the plastic too much. You can use an oven on low temperature too (keep it lower than 175C), but this process is a bit more difficult as it involves a bit of temperature regulation.
 
 
 
Melting Milk Bottle Tops
 
Preparation
 
Before you can begin melting and making with your milk bottle caps and other HDPE plastic items, you need to prepare your materials.
 

• Make sure all your bottle tops and plastic items are clean and any foodstuffs, grease, and labels have been removed.

 

• For larger items, such as milk and water bottles, you need to cut up the plastic into strips or 1cm pieces to ensure that the plastic melts evenly and no air bubbles are created. Milk bottle tops are small and thin enough to be melted without being shredded.

 

• We recommend shorting your bottle tops by colour—this will save you time in the long run if you decide to create a DIY product using only green plastics, for example. In our example pictures we have just used what we had available, so there's a big mix of colours!)

Tools Needed to Melt Your Plastic Bottle Tops

Once your bottle tops are sorted and sparkling clean, you are ready to begin melting them! Here are the tools you will need:
 

• Standard convection oven or toaster oven/panini press

 

• Greaseproof paper

 

• Heatproof gloves, such as Silicon gloves (avoid fabric materials as the melted plastic may stick to this)

 

• Mould/former

 

• Clamps (optional)

Method - How to Melt Milk Bottle Tops at Home
 
There are two different appliances people most often use to melt HDPE at home: a normal kitchen oven or a sandwich/toastie maker. The method for using both types of ovens are largely the same, but when using a toastie maker or panini press, you will not have to regulate the temperature.
 
Here’s how you melt milk bottle tops:



Step 1 

Stick your greaseproof paper to a metal baking sheet or the surface of your panini press using cooking spray or a small amount of cooking oil. Any plastic that gets stuck to the baking tray will be practically unmoveable, so make sure you use plenty of greaseproof paper.

We used some small dabs of butter, as it's all we had available. It seemed to work pretty well.

 

Step 2

Place a flat layer of bottle tops onto your tray or press. You can choose to use one colour of plastic or create a marbling effect by using a rainbow of different colours.




Step 3

Put your baking tray in an oven that has been preheated to 175 degrees Celsius (about 350 degrees Fahrenheit). It should take somewhere between 5 and 10 minutes to melt milk bottle tops. Larger pieces of HDPE will take longer.

If you are using a sandwich press or toastie maker (like we are!), simply lower the lid and leave until the bottle caps have melted.
 
 

Step 4
 

Once your first layer of milk bottle tops has melted, you can add more caps on top, if you want to make a larger block of HDPE.



Repeat the above melting process until you have used all available plastic.

You can collect the smaller bits into a larger block by pressing them together.




Step 5

After you have melted the required amount of HDPE and it is molten, you can begin to form the plastic. First, fold the plastic over on top of itself several times and press down to ensure any air bubbles are removed.

This piece has still got some air bubbles in so needs more work.



Repeat this process a few times, reheating the plastic between folds as it cools quickly.

If you are mixing multiple colours of HDPE, you can twist the melted plastic to combine the different colours. Make sure to use gloves when handling the HDPE as it will be very hot.

Once you have a melted mass of HDPE, you need to form it into a block and remove any air bubbles. Here’s how to do that:
 

• Transfer the melted HDPE to a square tin or wooden mould/former, which has been lined with more greaseproof paper (this can be made easily by screwing four scrap pieces of wood together).

 

• Compress the HDPE into the mould using a weight. You can attach clamps or place the mould into a vice for the best results.

 

• Depending on the size of your plastic sheet, it can take anywhere from 10 minutes to over an hour for the HDPE to cool.

 
Projects
 
With a selection of homemade HDPE sheets and blocks to hand, you can create a wide range of different DIY items for the home and garden! Everything from storage containers and chopping boards to pens and ornaments can be made from HDPE plastic, with a little bit of know-how.
 
What’s so great about HDPE plastic is that it can be melted down again and again. If you make a mistake when crafting a new plastic bowl, or there are too many bubbles in your first block of plastic, simply place it back into the oven and begin the process all over again.
 
If you want to start making some DIY projects at home, but do not have a large collection of HDPE plastic to hand, you can order bespoke sheets from our website. We cut High-Density Polyethylene and other recycled plastics to any size and shape! Get an instant quote today on our website.

If you found this interesting and are wondering where to start, why not check out Part 1 of this series: 25 Plastic Items You Can Melt Down and Reuse at Home

Next week we will be making something with our newly recycled plastic bottle tops, so don't forget to check back soon!