This work is derived from an diagram originally published in the October 1983 issue of MD&DI titled "The Three Step Plastics Identification Method". The method actually has more than three steps in some cases hence I have re-titled it. Over the years I have frequently found myself using this method and hope that others will find it as useful.
Some characteristics are subjective. Others are affected by plastic additives (pigmentation, plasticizers, flame-retardants, etc...). Therefore the results of this method may be inconclusive but will generally help one narrow down the possibilities. It helps a great deal to have experience handling a variety of plastics.
The are many new plastics that are not listed. As I find the time I'll add others. If you characterize a plastic that is not listed e-mail me the info and I'll add it. In time I'll try to add useful links and/or technical information about the plastics that are referenced.