Using The Burn Test to Identify Plastic Materials
Here is a simplified guide that will help you to identify many common types of plastic materials using a flame source such as a cigarette lighter, torch, or bottled gas burner. Naturally, the burn test should be used only for tentative identification. Many complex plastic compounds require a rigorous spectral or destructive chemical analysis for a positive identification.
To initially determine whether a material is thermoplastic (meltable) or thermoset (non-meltable) type, heat a metal or glass stirring rod until it glows red or orange (to about 500°F / 260°C) and press it against the sample. If the sample softens, the material is a thermoplastic; if it does not, it's probably a thermoset.
Next, hold the sample to the edge of a flame until it ignites. If no flame is produced quickly, hold the sample in the flame for about 10 seconds. If the material burns, note the color of the flame, the nature of the smoke, the presence of soot in the air and whether, while burning, the sample drips.
Next, extinguish the flame and cautiously smell the fumes. To identify the odor, samples of known plastic samples for comparison can be most helpful. Finally, check your observations against the known characteristics of each plastic as shown in the table below. Once you have made a tentative identification, it is usually desirable to repeat the flame test once or twice to confirm the results of the original identification. Remember that additives may affect results. For example: flame retardants can mask the polymer material's normal flame & smoke burning characteristics.
NOTE: The Burn Test Characteristics Table below is also available for download in easy-to-print one-page Download/Open PDF Version Now.
PLASTIC MATERIAL BURN TEST CHARACTERISTICS
|
Materials
|
No Flame
|
Burns, but Extinguishes
on Removal of Flame Source
|
Continues to Burn after
removal of Flame Source
|
Remarks
|
Odor
|
Odor
|
Color of Flame
|
Drips
|
Odor
|
Color of Flame
|
Drips
|
Speed of Burning
|
THERMOPLASTICS
|
|
|
|
Acrid
|
Yellow,
blue edges
|
No
|
Acrid
|
Yellow,
blue edges
|
Yes
|
Slow
|
Black smoke
with soot in air
|
Acetals
|
-
|
-
|
-
|
-
|
Formaldehyde
|
Blue,
no smoke
|
Yes
|
Slow
|
|
Acrylics
|
-
|
-
|
-
|
-
|
Fruity
|
Blue,
yellow tip
|
No (cast)
Yes (molded)
|
Slow
|
Flame may spurt
if rubber modified
|
Cellulosics
|
|
|
|
|
|
|
|
|
|
Acetate
|
-
|
Vinegar
|
Yellow
with sparks
|
No
|
Vinegar
|
Yellow
|
Yes
|
Slow
|
Flame may spark
|
Acetate Butyrate
|
-
|
-
|
-
|
-
|
Rancid butter
|
Blue,
yellow tip
|
Yes
|
Slow
|
Flame may spark
|
Ethyl Cellulose
|
-
|
-
|
-
|
-
|
Burnt sugar
|
Yellow,
blue edges
|
Yes
|
Rapid
|
-
|
Nitrate
|
-
|
-
|
-
|
-
|
camphor
|
White
|
No
|
Rapid
|
-
|
Propionate
|
-
|
-
|
-
|
-
|
Burnt sugar
|
Blue,
yellow tip
|
Yes
|
Rapid
|
-
|
Chlorinated Polyether
|
-
|
|
Green,
yellow tip
|
No
|
-
|
-
|
-
|
-
|
Black smoke
with soot in air
|
Fluorocarbons
|
|
|
|
|
|
|
|
|
|
FEP
|
Faint odor of
burnt hair
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
Deforms;
no combustion,
but drips
|
PTFE
|
Faint odor of
burnt hair
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
Deforms;
does not drip
|
CTFE
|
faint odor of
acetic acid
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
Deforms;
no combustion,
but drips
|
PVDF
|
acidic
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
Deforms
|
Nylons
|
|
|
|
|
|
|
|
|
|
Type 6
|
-
|
-
|
-
|
-
|
Burnt wool
|
Blue,
yellow tip
|
Yes
|
Slow
|
-
|
Type 6/6
|
-
|
Burnt wool
or hair
|
Blue,
yellow tip
|
Yes
|
-
|
-
|
-
|
Slow
|
More rigid than
Type 6 nylon
|
Phenoxies
|
-
|
Acridd
|
Yellowc
|
Noc
|
Acridd
|
Yellowd
|
Yesd
|
Slowd
|
Black smoke
with soot in air
|
Polycarbonates
|
-
|
Faint, sweet
aromatic ester
|
Orange
|
Yes
|
-
|
-
|
-
|
-
|
Black smoke
with soot in air
|
Polyethylenes
|
-
|
-
|
-
|
-
|
Paraffin
|
Blue,
yellow tip
|
Yes
|
Slow
|
Floats in water
|
Polyphenylene
|
|
|
|
|
|
|
|
|
|
Oxides (PPO)
|
-
|
Phenol
|
Yellow-orange
|
No
|
-
|
-
|
-
|
-
|
Flame spurts;
very difficult to ignite
|
Modified Grade
|
-
|
Phenol
|
Yellow-orange
|
No
|
-
|
-
|
-
|
-
|
flame spurts;
difficult to ignite,
soot in air
|
Polyimides
|
b
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
Chars; material
very rigid
|
Polypropylenes
|
-
|
Acrida
|
Yellowa
|
Yellowa
|
Sweet
|
Blue,
yellow tip
|
Yes
|
Slow
|
Floats in water;
more difficult to scratch
than polyethylene
|
Polystyrenes
|
-
|
-
|
-
|
-
|
Illuminating Gas
|
Yellow
|
Yes
|
Rapid
|
Dense black smoke
with soot in air
|
Polysulfones
|
-
|
b
|
Orange
|
Orange
|
-
|
-
|
-
|
-
|
Black smoke
|
Polyurethanes
|
-
|
-
|
-
|
-
|
b
|
Yellow
|
No
|
Slow
|
Black smoke
|
Vinyls
Flexible
|
-
|
Hydrochloric acid
|
Yellow with
green spurts
|
No
|
-
|
-
|
-
|
-
|
Chars, melts
|
Rigid
|
-
|
Hydrochloric acid
|
Yellow with
green spurts
|
No
|
-
|
-
|
-
|
-
|
Chars, melts
|
Polyblends
|
|
|
|
|
|
|
|
|
|
ABS/Polycarbonate
|
-
|
-
|
-
|
-
|
b
|
Yellow,
blue edges
|
No
|
-
|
Black smoke
with soot in air
|
ABS/PVC
|
-
|
Acrid
|
Yellow, blue edges
|
No
|
-
|
-
|
-
|
-
|
Black smoke
with soot in air
|
PVC/Acrylic
|
-
|
Fruity
|
Blue, yellow tip
|
No
|
-
|
-
|
-
|
-
|
|
THERMOSETS
|
Alkyds
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
Diallyl Phthalates
|
-
|
-
|
-
|
-
|
Phenolic
|
Yellow
|
No
|
Slow
|
Black smoke, cracks
|
Diglycol Carbonate
|
-
|
-
|
-
|
-
|
Acrid
|
Yellow
|
No
|
Slow
|
Black smoke
with soot
|
Epoxies
|
-
|
-
|
-
|
-
|
Phenol
|
Black smoke
|
No
|
Slow
|
Black smoke
with soot in air
|
Melamines
|
Formaldehyde
and fish
|
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
Phenolics
|
Formaldehyde
and phenolc
|
Phenol and wood or paperd
|
Yellowd
|
No
|
-
|
-
|
-
|
-
|
May crack
|
Polyesters
|
-
|
Hydrochloric acida
|
Yellowa
|
No
|
b
|
Yellow,
blue edges
|
No
|
Slow
|
Cracks and breaks
|
Silicones
|
b
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
Deforms
|
Ureas
|
Formaldehyde
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
a Flame retardant b Nondescript c Inorganic filler dOrganic filler
|
Ref: Materials Engineering, Penton/IPC, Cleveland, Ohio
|