When you go to the paint store and buy a can of paint, you will find paints that are labeled as stain resistant or stain resistant. Are you familiar with the term "anti-fouling"? Do you know what stains paint resists and how do paint companies test them?
The stains tested by the paint company include common household stains. They can be divided into hydrophobic and hydrophilic stains, as follows:
Hydrophobic stains: These stains are oil-based materials such as cooking oil, newspaper ink, crayons, lipstick, pencils, etc.
Hydrophilic stains: These stains are water-based materials such as tea, coffee, soy sauce, etc.
The stain resistance test method is shown below.
Apply two paints side by side on black PVC board.
Apply several types of stains horizontally over both paints. Wait 15 minutes.
Wipe half of the stained area with a damp cloth.
After drying, check to see if stains remain on the paint film. A paint film with good resistance will reduce staining. The surface of the paint film can only be oriented towards more hydrophilic or more hydrophobic. Because "like attracts", a hydrophobic surface will attract hydrophobic stains, and a hydrophilic surface will attract hydrophilic stains, making it harder to clean. Paint companies will strive to achieve a balance of hydrophobic and hydrophilic properties on the paint film surface. They also use additives to keep stains from penetrating into the paint film.
In addition, there is also a stain resistance Tester dedicated to the stain resistance test of architectural coatings, details can be found at: https://www.nbchao.com/list130/