Plastic bags are something that we all have lying around. Most of these bags can be recycled. You can even recycle them yourself at home. In this project I am going to show you how to fuse plastic bags together to make thick sheets of plastic that you can use in your craft projects.
Step 1: Watch the Video
Here is a video walkthrough of the project.
Step 2: Materials
Here are the materials and tools that you will need for this project.
Plastic Bags (such as HDPE grocery bags)
Baking Parchment Paper (rated for at least 400 degrees Fahrenheit)
Metal Baking Sheets
Heat Resistant Weights
Step 3: Acquire a Lot of Plastic Bags
The first thing that you need to do is acquire a lot of plastic bags. In this project, I used a total of 64 plastic grocery bags. It took quite a while to collect this many bags. Every time I went to the grocery store I just saved the bags and I kept them in my pantry.
All the bags need to be clean and dry. So if there is any food residue on a bag, you can't use it. If the bags have any water on them, let them thoroughly dry out before storing them.
The bags that I used were "High-Density Polyethylene" (HDPE). This is the standard in most American grocery stores. "Low-Density Polyethylene" bags can also work but be aware that they have a much lower melting point.
It doesn't matter where you get the bags from. Different stores may use different color bags but as long as it is made out of the same kind of plastic, it will work.
Step 4: Cut the Bags Into Sheets
Next you need to cut the bags into sheets. Start by cutting the bottom edge just above the seam. Then cut off the handles by cutting a line straight across just below the top edge. You now have a plastic tube. At this point, you can make the tube into a sheet by cutting a slit down the side. I wanted to have a plain white sheet with no writing or logos. So I also cut off the whole front panel of the bag. Repeat this for each of the bags.
Step 5: Fuse Four Plastic Sheets Together
Now you are ready to start combining the plastic sheets. Start by tearing off a large piece of baking parchment. Then lay it on top of a heat resistant surface. My normal work table has a plastic finish on top. So I decided to work on a scrap piece of wooden construction board.
Next lay the plastic sheets on top of one another. Try to line them up as well as you can. Then place another large piece of baking parchment on top of the plastic sheets.
Turn on your iron and set it to the medium temperature setting. Press the iron down firmly over the center of the plastic sheets. Slowly slide the iron across the paper toward the edge. Press down firmly as you go. Iron over the whole sheet.
After you have ironed the whole sheet a few times, lift up the top piece of parchment and check to see if the plastic sheets are fused together. If the sheets can still be easily separated, your iron may be set to low. Turn up the temperature a little and iron over the sheets again. If however you see holes melted in the plastic, then your iron is too hot and you should turn it down a little. You want to use the minimum heat required to fuse the bags together.
Once you have done this, you should have a single four-ply sheet of plastic. Repeat this process with the rest of your bags, making as many four-ply sheets as you can. We will combine these later into thicker sheets.
Step 6: Fuse Together Thicker Sheets of Plastic
To make thicker sheets of plastic all you have to do is combine the four-ply sheets that we made in the last step. Through trial and error, I have determined that the four-ply sheets are the best thickness for fusing together. With individual sheets it is easy to accidentally melt holes in them. With sheets that are thicker than four-ply, it is harder to get them to fuse together properly.
So take two four-ply sheets of plastic and place them between the pieces of baking parchment. Iron over them, pressing firmly as you go. You may need to increase the temperature of the iron slightly to get them to fuse together. When you are done, you should have an eight-ply sheet of plastic.
To make your plastic sheets even thicker, continue fusing on more four-ply pieces of plastic. With each additional four-ply sheet that you add, turn over your stack so that you alternate between the front and back sides. If you kept fusing on layers to only one side, your sheet might warp and start to curl. Adding layers to both sides helps to prevent this. Continue adding layers until you reach the appropriate thickness for your intended project.
A four-ply sheet can be used to make light raincoats and bags. An eight-ply sheet can be used to make a heavier coat or bag. With twelve or more fused sheets you can make backpacks and laptop bags. Twenty-four layers will give you thin sheets of hard plastic that you can use to make models and hard crafts. Sixty-four layers will give you 0.1 inch (2.5mm) hard plastic that you can use to make containers and rigid parts out of.
Step 7: Press and Re-Melt Thicker Sheets to Strengthen Them
In between each layer there are gaps and bubbles that will make the plastic weaker and more flimsy. If you want to make plastic sheets that are very hard and sturdy, it may be necessary to press and remelt them. To do this you will need a pair of matching metal baking sheets and some heat resistant weights such as bricks.
Set one metal baking sheet down on top of your work surface. Then place a piece of baking parchment on top. Then set your combined plastic sheet in the center of the parchment. Place another piece of parchment over it. Then add the second metal baking sheet on top of that. To press them together, add your weight on top.
Then place it in an oven that is set to 400 degrees Fahrenheit (about 200 degrees Celsius). Let this sit in the oven for half an hour. Then take it out of the oven to cool. Leave the weights on top. This will help prevent warping. When everything has cooled to room temperature, remove the weights.
Inspect the edges of the plastic. If they have fused into an almost solid piece then you are done. If not, then you may need to repeat this step and increase the temperature to 425 degrees or 450 degrees.
Step 8: Trim the Edges
The edges will probably be jagged and not uniform. Take a pair of sharp scissors and trim the edges until you are left with an even thickness all the way around.