Firstly, you can determine the quality by appearence.
1.Measure the size especially for the THICKNESS.
If the thickness not reach your requirement, it means, the manufacture does not use enough raw materials to produce. It leads to the low cost.
2.Check the fiber of glass wool and contents of shot
The fiber of good quality glass wool is long and thin. The contents of shot should be below 1%.(No visible shot can be seen by eyes). It affects the performance of final products, such as thermal insulation, sound insulation and water resistance, etc. It decides by the quality of raw materials and production line. Small factories usually buy bad quality raw materials and do not have a QC to check the quality when production. It leads to the low cost.
3.Evenness of glass wool
High quality of glass wool made by good production lines is smooth and evenly.
4.Color of glass wool
Good quality glass wool has a bright color.
5.Package of glass wool
For glass wool blanket, it often transported by vacuum bag. It can reduce the volumn obviously. Good packing machine can shrink more, so it can pack more glass wool blanket in a container. The more quantity a container can contain, the lower the price will be.
Secondly, several simple actions to identify.
1.Compress the glass wool by hands. Simulate the pressure when building houses or other uses to test whether it can afford.
Bad quality glass wool will deform or the surface will unglued.
2.Release the hand to see, whether it can rebound back to what it was.
Good quality glass wool has a good elasticity.
If further or profesional tests are required, following technical date is our index and China standard: