Old substrates
What damage to the old coating, constituting the foundation of the new one, must be checked before reworking it?
Before applying a new coating, the following should be checked for damage to the old coating:
1) Dirty;
2) discoloration, fungus, pubescence;
3) calcification;
4) insufficient grip;
5) scratches;
6) the presence of blisters;
7) the presence of eruptions;
8) improper binder structure.
Please list the possibilities of testing the adhesion of the coating to the substrate. The adhesion of the coating to the substrate can be determined by the following tests:
1) scratch attempts;
2) zigzag cut;
3) adhesive tape test;
4) adhesion testing device.
How can you distinguish between a mineral paint and an organic coating on a facade??
Organic coatings are burnt when attempted to burn. Organic coatings are soluble in removers.
Please describe the test to distinguish a silicate paint coating from a lime paint coating.
The type of paint is tested with hydrochloric acid. There is a strong turbulence when washing off the lime paint, because hydrochloric acid displaces carbonic acid from calcium carbonate. When washing off the silicate paint, no such disturbance is observed. In this test, only carbon dioxide is separated from calcium carbonate (chalk), being a filler.
How can one distinguish between a coating of dispersion paint and a coating of solvent-based paint on the facade of a building??
Dispersion paints are dissolved by nitro solvents. Solvent-based paints are also dissolved by white spirit.
As can be said, whether the window has been painted with alkyd paint, or dispersion?
Dispersion paint coatings are strongly dissolved by nitro solvents, on the other hand, alkyd coatings dissolve poorly.
Describe a simple experience, by which the thermoplastic acrylic coating can be recognized. Rub with a cloth moistened with a nitro thinner on an inconspicuous place, e.g. in the area of the car engine. If it is an acrylic varnish coating, it will be dissolved by the nitro diluent.
How can you distinguish a two-layer "metallic" paint coating on a car from the same coating?, but single-layer?
Such a distinction is made possible by performing a grinding test. If the water when wet sanding stains with a metallic shade, it is a single layer coating.
If it is a two-layer coating, only the clearcoat layer is sanded off. During wet grinding, the water then only stains white.