Re: Oil primer with paint and alkyd medium?
Normally one would have expected half a dozen responses by now, maybe everyone is out enjoying the spring weather? (Snowing here today.)
You definitely can use your white oil paint and some alkyd medium to make an oil ground. It will be very slippery and non absorbent, perhaps a bit more than you want. I wouldn't add more of the medium than needed to speed the drying time, certainly not more than the maker recommends. A general max is around 20% for some products if it doesn't say.
To give it a bit more tooth and less shine, add some calcium carbonate (marble dust, whiting, chalk). You can buy calcium carbonate soil conditionar at most gardening shops and whiting at paint stores. No need to pay a premium for "artists" marble dust. Just be sure it is a very fine grit powder. Be sure to test whatever mix you come up with to determine the amount you like best, before covering all your panels.
As for the sealing you don't have to use GAC100. I would save that for other stuff since it is so expensive. Any commercial primer will be fine. Zinsser, Kills, XIM UMA, Bulls Eye Wax Free Shellac, plain old acrylic Gesso and several other materials will do the job. You do not need to worry about SID (Substance Induced Discoloration) with oils on wood panels like you do with Acrylics. Just seal all sides and edges with something that will help keep the moisture out. You can sand the sealer to make it more smooth but you don't need to. The viscosity of the oil primer depends on how you apply it, knife or brush, and how smooth you want it to be. Again, test before proceeding on working panels. Let the primer / sealer dry for the recommended time before putting your oil ground on there.
If you have not already purchased the MDF panels, I would recommend using tempered hardboard from Lowe's instead. The 1/8" works well up to 11x14, I prefer the 3/16th for larger than 9x12. If you already have the MDF, they will be OK to use. Just be sure to seal them well to prevent warping and expansion from moisture absorption.
Last edited by contumacious : 04-03-2019 at 11:14 AM.