Cedar releases natural oils, sap, and tannin. This release occurs at the knots. Blisters are forming over each knot. Scraping, sanding and priming may fix a few but then more blisters come up in different spots, and sure enough, the new spots have knots too.. Am I chasing this around like a chicken with no head……How can this blistering be stopped? I have used BIN Cover Stain on it. The BIN work great everywhere else but the knots…… A dark color is being used, oil based, applied in hot weather using Penetrol to slow drying and increase leveling. The blisters/bubbles go down to the knot, not inner layer paint bubbles..No problems with paint adhering to primer.

Is this a lumber problem, or a painting process problem? Virginia Cedar….A deep red cedar for sure, high aroma and red with little white grain…….

Any suggestions on how to stop the blisters forming over the knots?