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Burn Test Identification for Plastics

 

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

ABS
 
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