Not everyone gets to play with fire as part of their job, but as someone who works in the plastics industry I get too. Many times it is to melt plastic that ended up in a place that it should not be but it can also be used for a greater purpose; material identification.
A simple burn test can tell a lot about a material. Just from holding a controlled flame under a part for a few seconds multiple things can be used to determine the material. Some of these include:
- Color of the flame
- Smoke appearance
- Molten Drips
- Smell of burn
- Ignition time
- Extinction time
- Change in color
- Melt/No-melt
All of these things give hints to what material you are working with
| Material | Flame Color | Drips | Smell | Burn w/o flame | Smoke |
| ABS | Yellow with Blue | Yes | Acrid | Slow continues burn | Black smoke with soot |
| Acetal | Blue | Yes | Formaldehyde | Slow continues burn | No smoke |
| Acrylic | Blue with Yellow | Yes | Fruity | Slow continues burn | N/A |
| PC | Orange | Yes with flame | Sweet | Self Extinguishing | Black smoke with soot |
| PE | Blue with Yellow Tip | Yes | Wax | Slow continues burn | N/A |
| PP | Yellow | Yes | Sweet | Fast continues burn | N/A |
| PS | Yellow | Yes | Gassy | Slow continues burn | Thick black smoke with soot |
| PU | Yellow | No | N/A | Slow continues burning | Black Smoke |
| PVC | Yellow and Green | No, Chars | Hydrochloric Acid | Chars, Melts | Chars |
| Nylon | Blue with Yellow Tip | Yes | Burnt Hair | Slow continues burn | N/A |
Using these clues the material of a part can be narrowed down if not determined. Many of these results are very similar and smells can be quick to miss at ignition. It may be necessary to try multiple times with one material to see all the different characteristics to look at.
As always remember to stay safe when working with fire and test in a well ventilated area.