What is the Method of Adhesive Test by Using Mylar Film?

This is a question from one of our customers. And it is regarding the water-soluble polyester resin. Mylar film here refers to the polyester film.
After these potential customers receive our samples of WSP resin, they need to conduct an important test about adhesion.
Good adhesive brings a positive result to the sizing process.
Here is the method.
1. Make a 15% clear solution of polyester resin in soft water.
2. Apply this solution to dry completely by air drying
3. Solution must be applied on A4 paper size film in the form of a 3 to 5-inch circle
4. After the polyester film is fully dried, start rubbing by using a coin of yuan on that film.
(Minimum 100 runs are required for rubbing test.)
5. If the film of polyester resin is not disturbed after 100 runs, the adhesion is perfect.