You need to test for a two pack if you do not know what paint is already on the boat.
The reason for this is that if you put a two pack on top of a one pack it could react with it and 'pickle' the coating. You can quite safely put a one pack paint on top of a two pack but not the other way round.
Hence the tests below - two form Awlgrip and one from International.
Awlgrip Paints suggested methods.
Test One: Cross Hatch Adhesion
1. Select a test area or areas on the surface to be painted. Thoroughly clean, de-wax, and degrease this area.
2. With a single-edge razor blade, scribe a 2” x 2” test area in a 1/4” checkerboard pattern. The cuts must be deep enough to reach the substrate. On a thick fairing system this test may have to be done to several different layers.
3. Apply 3M #610, #895 or #898 3M Scotch Brand Filament Tape (or similar type of packaging tape) over the scribed area, making certain that the tape is tightly adhered to the test surface. Do not use masking tape.
4. With an abrupt yank, pull the tape back parallel to the surface. To pull the tape straight up will give no test at all.
5. Examine the test surface. If any square of old coating in the scribed area is removed, the adhesion has failed. All the failed layers must be removed.
Test Two: Solvent Resistance
1. Saturate a cotton ball or small wad of cloth with one of the Awlgrip Topcoat or Primer Reducers. (T0006 or T0003).
2. Tape the reducer saturated ball to the scribed area surface for 30 minutes.
3. After 30 minutes, remove the cotton ball. If the reducer has dissolved or severely softened the old coating, the coating is incompatible and must be removed. If the scribed area has remained intact, allow a 15 minute recovery period and repeat all steps in Test 1 again.
4. If any square areas are removed, all the failed layers must be removed.
International Paints suggested methods.
TESTING FOR COMPATIBILITY:
To test if an existing topside paint product is compatible with our two-part polyurethane finish (International Perfection) ; tape a cloth soaked in International Thinners No. 9 to the previously painted substrate for 24 hours. If the surface is softened, it is probably not compatible. In this instance only a one-part paint product should be applied.
