Sealing Knots for Painting

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Forum topic by JHuttIII posted 09-01-2017 08:03 PM 696 views 0 times favorited 3 replies Add to Favorites Watch
View JHuttIII's profile


2 posts in 1075 days

09-01-2017 08:03 PM

Recently bought our first home at the beginning of the year, and our Master bedroom needed a complete overhaul from head to toe. Everything is pretty much complete now with the exception of the trim/molding, which I removed too as it was in bad shape. I have all of the wood necessary (just using Pine), but am having difficulty finding a good method to not have any knots bleed through the paint.

When I rebuilt the closet threshold (did an expansion), I used a technique I found on YouTube by professional painters which entailed applying a couple layers of a bondo sealer over knots before priming. After about 3-4 coats of Kilz latex primer though, the knots still bled through. I was pretty shocked as I wasn’t expecting it to come through the Bondo layer.

After some further research online, what I have come up with now is to apply wood filler to the knots, then apply a couple of coats of BIN shellac primer (aerosol) before putting on my regular primer for the wood.

I rarely paint the wood I work with, so I don’t have a lot of technique down for this. Any help or guidance here would be most appreciated!

3 replies so far

View jdh122's profile


1167 posts in 3626 days

#1 posted 09-01-2017 08:41 PM

Shellac is about the only thing that works. Personally I don’t bother with a shellac-based primer, but rather put actual shellac over the knots (once they’re filled with wood filler). It dries in about 30 minutes, then use regular primer and then paint.

-- Jeremy, in the Acadian forests

View JHuttIII's profile


2 posts in 1075 days

#2 posted 09-01-2017 09:08 PM

Thanks for the reply. I was wondering if regular shellac or the BIN shellac primer choice would matter much. I hear a lot of people swear by the BIN stuff, but not sure if one would be better over the other.

View woodbutcherbynight's profile


6069 posts in 3217 days

#3 posted 09-02-2017 02:01 AM

I have taken the router to the offending knot and then glazed back over it with bondo.

-- Live to tell the stories, they sound better that way.

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