Why the information on the data sheet isn’t always what you need…

Depends on what the manufacturer determines to be pertinent for publication. I have also found that I can pull a data sheet from IDES and then pull one from the manufacturer from the IDES link--- qnd they a different---- the manufacturers version typically has more detail.

But if you are still missing something- contact the manufacturer for the specific value you need

keep in mind what's published is something the resin companies can defend in court. The data is generated from test plaques that have been molded under ideal conditions, using certified conditions (drying protocols, molding conditions etc,). When choosing a material, consider this data a starting point. Your values will probably be less because you're not molding test bars under perfect conditions.

right on Bill - they are unlikely to state the bad portions of their resin properties - quote - "we didn't say it wouldn't fade etc etc"

My own experience says that most (but not all) are honest but to obtain the tensile properties stated will often require unrealistic molding conditions as their results are on simple flat "dog bone" type test samples. The perfect new mold run on quoted temperatures is not too realistic - but of course we have the manufacturers stated "range of temperatures" - right!!

Try samples of PVC as molded and then subject them to post cross linking type temps - the values are enormously different but still the same material. Sad but true

You have to take all the numbers on a spec sheet with a grain of salt. You need to be able to judge the posted numbers as per the ASTM test method to related. A specified higher elongation of one material versus another should in real life hold true that the molded part in each material falls in line with the reported test numbers. One material with a lower tensile value should fail before the material with a higher reported value.

If you cannot trust this direct comparison------ then there should be no ASTM tests or specs for any functional physical value of any materials.

The values need to be viewed as relative comparisons only----- not actual values of complex molded shapes.