I've been doing a lot of "yard art" for our Farmers Market season coming up in June.

Priming the wood for outdoor use up here is a must. The directions on the can says to top coat within 2 weeks. I haven't found a good answer as to why. Does the primer loose something when you wait too long or what? My wife is getting backed up on finishing the cut outs and I'd like to prime them all at one time and be done with that part.

Harry, the primer does loose something, it loses it's bonding strength with the top coat, the primer cannot completely cure or dry or harden, if it does than the bonding properties are diminished significantly. Just think of it as the top coat needs to micro bond or mix with the primer between the layers to ensure a good secure and strong bond. After two weeks, with that particular primer you are using, they are saying that it will cure and be come too hard or dry for the a top coat to bond correctly.

I'm no expert but the experts (painting contractors) tell me that they only use a primer to seal a knotty wood or to seal in an odor. They claim that, if you use two coats of the color, it's the same as using a primer. I'd imagine that the same thing that John mentioned would apply to the coats of color, also.

I've done it both ways and can see no difference on the trim or doors I've painted. And, where I buy paint, primer is mere pennies less per gallon than the top coat. Less than $2.00 difference on a 5 gal pail. Not worth the hassle, IMHO.

Great point Gene, spot on. Same goes with a clear coat or varnish, many folks like to use a coat of sanding sealer before they apply varnish, it's a waste, just use the first coat of varnish as your sanding sealer.