Mike - i tried that stuff. works well and paint sticks fine. I found that it is not "wata pruf". Water penetrated the plug and the finish cracked. The plug also got heavier the longer I fished it.
I use Zinsser Oil based primer sealer. I also cut it with turps about 1/3 turps to 2/3 cover stain sealer. I get good penetration and it sands smooth leaving a good prime coat.
I made a plug priming rig from 4" PVC. I made it 15" long and it is sealed on one end with a cap - open on the other end with a screw on cover. I usually mix only enough primer to fill the container 1/2 full leaving room to dunk and tip over end to end. I use the mix untill it gets dust and crap in it leaving lumps on the plugs that are tough to get off. It is always at the ready to prime one or a number of plugs at one session. I use a pair of tongs to grab the plug and hang it to drip dry.
