I purchased a Norwegian pine shed some years ago and after painting with a water based paint the knots seeped through in significant sized globules which are sticky and problematic to remove.Is there a “solvent” available to overcome this problem?

  • 1
    I believe turpentine/mineral spirits/white spirit will usually dissolve sap.
    – FreeMan
    Jul 6 '20 at 17:48

You needed to seal the knots prior to painting. No matter what you do, it will continue to bleed through.

Remove the paint around the knots. Use solvent such as turpentine to remove the sap with a scraper and rags. Seal the knots with an appropriate knot sealer (available at any paint store). Prime the sealed knots, perhaps twice. Repaint the whole surface to even out the coverage.

Sometimes water based primer-sealers are acceptable as "knot sealer"; ask at the paint store or read the label. If this is the case, then the sealing and priming would be the same step.

  • Shellac to seal the knots? Or is this not "strong" enough?
    – gnicko
    Jul 8 '20 at 19:11
  • I have no idea, but it probably depends on what finish is going over it. I don't think shellac and exterior latex get along very well, for example. But I do a lot with "knotty" pine, and I just use the sealer/primer combo from my local paint store, or the transparent sealer that is applied before a translucent stain or other finish.
    – jdv
    Jul 9 '20 at 13:56

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