At what point does a NEW, semi-gloss, latex paint become an OLD paint finish? Another words, when painting over old paint, it’s recommended to cut the old sheen so the new paint will stick. Most manufacturers recommend waiting on a second coat for 4 hours. If it’s been 12-20 hours since the first coat, is it OK to paint over the old semi-gloss, or do I need to sand lightly?
Most of your info is wrong… you only need to lightly scruff up the old paint if it’s an oil base high gloss finish… otherwise whatever it is, just paint over it, after PROPER PREP THAT IS… …(you can indeed paint latex over oil too if necessary)… why do you think you need a second coat? ONE coat … as long as it covers, is all you need!!!