We do the same as Jim Sears describes, for the same reasons as Jim describes.
"I always use a single part paint on the antiques. Now PPG Concept is the best available and use the hardner."
However, Jim, I think the PPG DCC Concept paint should be referred-to as a two-part/component single-stage paint.
"CONCEPT® (DCC) Acrylic Urethane is a premium quality, single stage, two component refinish product designed to offer exceptional gloss and color match. It is available in conventional single-stage solid and metallic colors and can be used over all properly prepared OEM Finishes and cured air dried finishes."
We have also used PPG Omni (on select projects) which is a lower-cost two-part single-stage Urethane.
