How does elastomer identification work?

The flame test, or spark test, can be used to identify the elastomer type. To do this, a small amount of rubber is held in a small flame. The rubber can then be determined by its burning behavior, odor and the residues that are produced. Compare the properties with the following table.

Rubber type	Burning behavior	Odor	Residue
NR	Burns very well. Yellow, even flame	Characteristic odor	Sticky, greasy, soft
NBR	Burns very well. Uneven, flickering flame		Crumbles, slightly greasy
CR	Self-extinguishing, does not burn in its own flame	Pungent odor	Firm and grainy. Not greasy
IIR	Burns well. Yellow, sooty flame	Faint odor	A little greasy
EPDM	Burns very well. Sooty flame	Pungent odor	Fine-grained, slightly greasy
CSM	Does not burn in its own flame. Bright smoke when burning. Bright glow on the rubber, even a few seconds after removing the flame	Corrosive odor	Very fine-grained
FKM	Does not burn in its own flame. Bright smoke when burning.	Very strong, pungent odor	Hardly any residue
PU	Does not burn in its own flame. Liquefies immediately on contact with the flame	Strong characteristic odor	Very soft or liquid residue that can even drip
VMQ (silicone)	Does not burn in its own flame. Yellow-white flame with white smoke. Burning point turns white	Little intense odor	Solid and white

CAUTION: When burning, rubber can release toxic decomposition products into the air. Therefore, only use the smallest possible rubber sample and only smell it carefully.