hardner use

I am using enamel.

To add to the other's - I'd try a little somewhere where it doesn't show. Depending on the stage of cure of the paint that is down and the aggressiveness of the reducer in the paint to be applied, you may get lifting. You'll know in less than an hour if there is a problem like that. That type of reaction is not dependent on a hardener being used in the new paint. For example, PPG's OMNI MAE acrylic enamel used w/o hardener is not recommended by PPG to be recoated after initial dry with additional MAE (hardener or not) at any stage of cure. They will not guarantee that lifting will not occur when doing that. Your paint may be different but it's a good idea to be cautious in order to avoid an unpleasant surprise.

Rod

I've painted w/ hardner over old dry paint with no ill results.. however.. i imagine over new fresh paint.. there might be a problem with cure times being different ont he hardened vs non hardened coat..

I'm sure a paint pro will be here soon to give you a more definative answer.. perhaps NCKS .. Rod.. etc..etc..

Soundguy