Film recoatability refers to the ability of Coating to bond well with the original coating when it is reapplied on the surface of a dried film. In practical Coating applications, film recoating performance is one of the keys to the long-term stability of coatings. The following are two commonly used methods for measuring film recoatability:
Cross-cut method
The cross-cut method is to evaluate the recoatability of the film by scratching a cross-score on the surface of the original coating, and then re-coating a layer of Coating on the score to observe whether the coating is tightly combined with the original coating. The method is as follows:
(1) Use a scale to draw two sets of parallel lines on the surface of the drying film, and the line spacing is generally 1 mm.
(2) Draw a cross along a set of lines, and the scale depth is generally half of the thickness of the original film.
(3) Apply the new Coating to the cross, and after drying, disbond the Coating with tape or fingers.
(4) Observe whether the Coating is completely disbonded. If the Coating disbonding is more, it means that the film has poor recoatability.
Pencil hardness method
The pencil hardness method is to scratch the surface of the original coating with pencils of different hardness, and then apply a new layer of Coating to the scratch to observe the combination of the new Coating and the original coating to evaluate the recoatability of the film. The method is as follows:
(1) Scratch the surface of the film with pencils of different hardness.
(2) Apply the new Coating to the scratch, and after drying, disbond the Coating with tape or fingers.
(3) Observe whether the Coating is completely disbonding. If the new Coating is well combined, it means that the film has better recoatability.
The above two methods are common methods for measuring film recoatability. Choosing an appropriate method for testing can effectively evaluate the recoating performance of Coatings. NBchao prompts you: When testing, you should choose appropriate test tools and test conditions, and reasonably interpret and analyze the test results. At the same time, Coating substrate, construction conditions and other factors will also affect film recoating performance. Therefore, in practical applications, a variety of factors need to be comprehensively considered.
