Weld Plastic Using Household Plastics
Weld plastic using household plastics begins with determining what kind of plastic you will be welding. But I’m getting ahead of myself. First thing you need to know about welding is that welding requires additional material to combine two pieces together. In the normal welding of steel, you have a steel welding rod that melts into the two pieces being welded fusing them together.
It is the same thing with plastic welding. You will need the fusing material to be of the same type of material as the two pieces you are welding together to achieve the strongest weld possible. You could buy plastic welding rods or you could find the same type of plastic material in your home. But how do you tell which item is the same type of plastic?
Where do you find the information?
Do you know that you can determine the plastic-type by looking for the recycling symbol on the part to be welded? The number inside the triangle and the letters stamped next to the recycle symbol indicate the type of material. The following list is the types of plastic. The numbers and letters represent the plastic material to be welded. This is the first piece of information needed in order to weld plastic using household plastics.
Recycle symbol
- #1 or PET (Polyethylene Terephthalate)
- #2 or HDPE (High-Density Polyethylene)
- #3 or PVC (Polyvinyl Chloride)
- #4 or LDPE (Low-Density Polyethylene)
- #5 or PP (Polypropylene)
- #6 or PS (Polystyrene)
- #7 or Other (BPA, Polycarbonate, and LEXAN)
Now you know what type of plastic your working with. The next question becomes where can I find more of this same plastic material to use as my “plastic welding rods” or filler material? You’re standing in the middle of a gold mine of plastics. You just need to look for the likely things that are made up of that same material. Once you find an item make sure that you clean it thoroughly before using it to weld. Listed below are the seven plastic categories and the things usually made from those plastics.
Best shape for welding
Cut the filler material into 1/4″ to 1/2″ wide strips for the best results. Use a heat gun to warm the piece to be welded and then heat/weld the strip into the crack.
Safety
You will be heating up the plastic and vapors may develop during the process of welding the plastic. For more safely inhalation information of plastic use the material safety data sheets listed.
- PET MSDS sheet
- HDPE MSDS sheet
- PVC MSDS sheet
- LDPE MSDS sheet
- PP MSDS sheet
- PS MSDS sheet
- PC Polycarbonate MSDS sheet
#1 or PET (Polyethylene Terephthalate)
PET(E) plastic is used to make many common household items. Usually clear in color, the vast majority of disposable beverage and food containers and bottles are made of #1 plastic.
| beverage bottles | medicine jars | rope |
| shampoo bottles | mouthwash bottles | soft drink bottles |
| water bottles | mineral water bottles | household cleaning product containers |
#2 or HDPE (High-Density Polyethylene)
HDPE is usually opaque in color. HDPE products made from this plastic include…
| milk containers | motor oil containers | shampoo containers | conditioner containers |
| soap bottles | detergent bottles | bleach bottles | fabric conditioner bottles |
| snack food boxes | cereal box liners | non-carbonated drinks bottles | toys |
| buckets | rigid pipes | crates | plant pots |
| plastic wood | garden furniture | butter tubs |
#3 or PVC (Polyvinyl Chloride)
PVC is commonly found in…
| plumbing pipes | fittings | wire and cable sheathing |
| Credit cards | food wrap | bottles for cooking oil |
| shower curtains | inflatable mattresses |
#4 or LDPE (Low-Density Polyethylene)
Items such as…
| cling-film | sandwich bags | squeezable bottles |
| plastic grocery bags | packaging films | bubble wrap |
| some bottle tops | bread bags |
#5 or PP (Polypropylene)
It is used to make…
| lunch boxes | margarine containers | yogurt pots |
| syrup bottles | prescription bottles | potato chip bags |
| crates | plant pots | drinking straws |
| ketchup | syrup bottles | kitchenware and “microwave-safe” containers |
#6 or PS (Polystyrene)
Overwhelming evidence suggests that this type of plastic leaches potentially toxic chemicals, especially when heated. It would be wise to avoid welding #6 plastic as much as possible. Items made from PS include…
| disposable coffee cups | plastic food boxes | plastic cutlery | packing foam |
| yogurt containers | egg boxes | fast food trays | video cases |
| vending cups | seed trays | coat hangers | low-cost brittle toys |
#7 or Other (BPA, Polycarbonate, and LEXAN)
If its made from this stuff follow the respiratory guidelines from the MSDS sheet. Polycarbonate falls into this category, including the highly toxic BPA. Polycarbonate (PC) is used in…
| baby bottles | compact discs | medical storage containers |
| sports equipment | medical and dental devices | CD’s and DVD’s |
Cut into strips
The best shape for the filler material is a wide thin strip. If your welding tool is a soldering iron the material should be on the narrow side. If you prefer using a heat gun the best shape would be wider. You can use a set of heavy-duty shears to cut the material into strips.
All the information
Verify that you have the right material using the recycle codes. You now have all the knowledge you need to weld plastic using household plastics. You know where to find your material for “welding rods/filler material” and you know where to look on the piece to be welded. Also, you have all the safety inhalation information on each type of plastic thru the use of the MSDS sheets.
Related Article: DIY Plastic Welding
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