Automotive paint

[drunken monkey]

I was reading an article about classic car restoration and the topic of painting and polishing came up. In the article, it was mentioned that there is a "sweet" period for sanding and polishing. Before that, the paint is too soft and after that it is too hard to work. Is this paint specific and does it relate to what we use and what we do?

Is there a perfect sanding time or is it generally better to let the paint fully cure?

[Joe Blyth]

Maybe if you use automotive lacquers, but probably not hobby types like Tamiya or Testors. I've waited several months for Tamiya lacquer to cure and sanded/polished just fine.

[gionc]

I felt the same with the 2k Lecher Macrofan that is a pro automotive stuff: at last those products aren't designed to be polished (or at least not how we meant).
After 24h my 2k is just glass, I'll do nothing with compound if meshes wheren't used.

I found another bug on the matter: I masked with 3m tape (pro stuff for body shop works) after a day and the tape leave marks on the surface, so may be is just glass at touch but not cured at 100% (kat kind: medium, appropriate for the season)

Before 12-16H I haven't the appeal of something 100% dry, you'll feel some "friction".

[bri g]

drunkenmonkey, I personally use automotive 2k urethane clear for all my models and don't find any difference when sanding/polishing a week after or a month after. To test, I just dig my fingernail into the paint (somewhere where it won't be seen if a mark is made) and when it doesn't leave a mark, its good for polishing

gionc, I find the same problem with all types of masking tape including tamiya. if the paint is not fully cured, the adhesive will react to the 2k clear and etch it. to be safe though, I don't leave the masking tape on the model too long, as soon as I'm done painting, I give it about 30 minutes to dry and then take the tape off.