bought some kapchi coatings primer filler last week good stuff can the hardener be used with 2 k paint on the tin it says 2k primer filler hardener thanks
2k paint hardener should be aliphatic di-isocyanate which is resistant to yellowing when exposed to daylight, sunlight or UV, but at typically 3 to 5 times the cost...
Fillers and others that are designed for "subsurface" applications could be a mixture of MDI's (Methylene di-isocyanate's, not so bad) and even TDI's (Toluene di-isocyanate's, not pleasant) whose polyurethane copolymers will yellow on exposure to sunlight and UV...
As others have said go with the product that's designed for the purpose