How to measure the hydrophilicity of the material

You can use test ink, focusing on qualitative testing;
or contact angle measuring instrument, focusing on quantitative testing.

Measure the angle of water, apply the material on the glass sheet, make the film, and then drip the water to measure
The wrong word just responded, see this

Test who is in contact with the corner, apply the material on the glass slice, the film forms, and then drip the water to measure

The contact angle captures the image of the moment of contact with the material in contact with the material. The material should be dissolved without so quickly