Identifying Plastics for Fabrication and Repair

It's important to identify the plastic you're welding as only like plastics can be joined. The simplest way is by performing a burn test.  

Take a small sliver or shaving of the material to be welded and light it with a flame, observe and smell the smoke. Most commonly: 

• For PVC: blackish smoke and acrid smell
• For Polyethylene (PE): no smoke, the melted material drips like candle wax and smells of wax
• For Polypropylene (PP): no smoke, the melted material drips like candle wax and smells of burnt oil
• For Polyamide (PA): no smoke, melted material pulls to form a thread and smells of burnt horn
• For Polycarbonate (PC): yellowish sooty smoke, sweet smell
• For ABS: blackish smoke, sooty flakes, sweet smell

​See our Plastics Identification Flow Chart for an expanded listing of plastics and their properties. ​

Recommended Further Reading

• Choosing the Right Tool for your next Plastic Welding Project
• ​Find the Correct Welding Temperature for your Project

Originally published: 9/19/2014