Different methods used to determine the type of plastic, when the type is originally unknown.

[1] [2]

Decision tree [2] [2]

Beilstein copper wire test

this is what it looks like if you get a green flame

boiling water test

When placed in boiling water for 30 seconds, does the material soften?

Soften: PET, ?

Doesn't soften: ?

burn test

[1]

does it float in water?

[1]

Floats: PP, LDPE, HDPE

Sinks: PS, PVC, PET

solubility

Some plastics are soluable (S) in a given solvent, some plastics will swell (SW), and some plastics are insoluable (I):

Gasoline Toluene Acetone Cyclohexanone
ABS SW S S S
LDPE, HDPE I I I I
PA (polyamides) I I I I
PET I I I I
PMMA I SW S S
PP I I I I
PPO I SW S S
PS S S S S
PVC I SW SW S