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Thread: Sap Bleeding Through Paint

  1. #1
    Join Date
    Feb 2003
    Location
    Slidell, LA
    Posts
    124

    Sap Bleeding Through Paint

    I replaced some exterior decorative trim on my front porch and, after installation, applied a coat of white primer (Glidden Gripper is the specific product) similar to Kilz. That was about a month ago and I haven't applied any top coat yet. I noticed that there is a orange-brown stain showing through in some areas that looks suspiciously like the grain pattern in the wood I installed. I applied another coat of primer (Kilz this time) but I'm beginning to worry that I may eventually see this through the top coat also. The wood I used was something the lumber yard called Arkansas Pine. It was pretty nice looking wood (almost clear) and it didn't seem to have any excessive amount of sap. Both of the primers were latex type. Any advice on the best way to block this from bleeding through?

  2. #2
    Join Date
    Feb 2003
    Location
    Lafayette, IN
    Posts
    3,583
    Quote Originally Posted by Jerry Solomon
    I replaced some exterior decorative trim on my front porch and, after installation, applied a coat of white primer (Glidden Gripper is the specific product) similar to Kilz. That was about a month ago and I haven't applied any top coat yet. I noticed that there is a orange-brown stain showing through in some areas that looks suspiciously like the grain pattern in the wood I installed. I applied another coat of primer (Kilz this time) but I'm beginning to worry that I may eventually see this through the top coat also. The wood I used was something the lumber yard called Arkansas Pine. It was pretty nice looking wood (almost clear) and it didn't seem to have any excessive amount of sap. Both of the primers were latex type. Any advice on the best way to block this from bleeding through?
    Ahhh, yes...the great primer primer. Glidden's Gripper is a good primer, but does not work well on some stains--it is intended to stick, not to be a stain-blocker (BTW, it's waterBORNE, not latex--subtle difference I won't go into here). Kilz is considered a stain-blocker, but won't necessarily block all stains. Repeat after me: "There is no such thing as a universal primer. " Say it again. The tannins in wood (not sap as you surmised--that actually comes out in thick globs) are essentially water-based, and therefore, waterbased primers will, for the most part, not work on them. Switch to Zinsser BIN, a white-pigmented shellac, or the oil Kilz, and you should have the stain sealed in and can then topcoat.

    Bottom line is that experience is what teaches which primers work on what stains, but as a rule of thumb, if the primer doesn't cover it, you need to switch to a primer with a different solvent base (water, oil, alcohol, xylene, etc.). Quick-dry is usually preferred as this doesn't allow the primer solvent to dissolve the stain and keep bringing it to the surface--it covers over it by flashing off quickly. Keep in mind, too, that sometimes, primers will seal in a stain without fully covering the color of the stain (think of it like putting plastic wrap over the stain--it's covered and sealed, but you can still see it). The solids in a heavy exterior acrylic will do that.
    Jason

    "Don't get stuck on stupid." --Lt. Gen. Russel Honore


  3. #3
    Join Date
    Feb 2003
    Location
    Slidell, LA
    Posts
    124

    Followup

    Jason - Thanks for the advice and I have a couple of followup questions. When applying the oil-based primer should I: (1) sand the existing primer?; (2) somehow remove the existing primer?; (3) after applying the oil-based primer, can I top-coat it with latex paint?

    I've heard things over the years about not using latex and oil paints on top of each other but can't remember what they were. Or for that matter, if they were correct to begin with.

  4. #4
    Join Date
    Feb 2003
    Location
    Lafayette, IN
    Posts
    3,583
    Quote Originally Posted by Jerry Solomon
    Jason - Thanks for the advice and I have a couple of followup questions. When applying the oil-based primer should I: (1) sand the existing primer?; (2) somehow remove the existing primer?; (3) after applying the oil-based primer, can I top-coat it with latex paint?

    I've heard things over the years about not using latex and oil paints on top of each other but can't remember what they were. Or for that matter, if they were correct to begin with.
    1. You can, but no need.
    2. No.
    3. Absolutely.

    The biggest problem exterior-wise is an oil topcoat over a latex topcoat--the oil will shrink and lose its flexibility and pull the latex off underneath, but that is not the case with a thin coat of oil primer over latex (actually most good WB exterior paints are now 100% acrylic). For interior, it is difficult to get latex to adhere to a smooth oil-based surface without a good bonding primer coat first.
    Jason

    "Don't get stuck on stupid." --Lt. Gen. Russel Honore


  5. #5

    Thumbs up

    YUP, YUP, YUP. Just what Jason posted. Bin is a great stain blocker.
    Steven Mendes

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