Sealing Knots

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Forum topic by LearningAsIGo posted 12-20-2012 07:51 PM 4628 views 0 times favorited 9 replies Add to Favorites Watch
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50 posts in 2836 days

12-20-2012 07:51 PM

I need to prime and paint some boards that have knots in them. I’m using dark paint, so I’m not sure if you will be able to tell if the knots bleed through?

Through googling I have seen that the general consensus seems to be that in order to seal knots you need to use BIN primer or else they will bleed through. I have definitely seen this with latex primer. Will knots bleed through oil based primer or can you use oil to seal them also?

9 replies so far

View Gerald Thompson's profile

Gerald Thompson

1118 posts in 2435 days

#1 posted 12-20-2012 08:30 PM

Use Zissner’s Seal Coat.

-- Jerry

View Cosmicsniper's profile


2202 posts in 3359 days

#2 posted 12-20-2012 08:34 PM

The BIN Primer is just dewaxed shellac, either clear or pigmented white. There are oil-based and latex primers out there, Kilz being one I have in stock. Rustoleum (Zinsser) also has water and oil-based variants.

The BIN primer will work regardless of the top-coat as shellac is universal in what can go on top of it, though I would typically use a water-based primer with a latex finish, like the aforementioned Kilz or the Rustoleum alternatives. However shellac is a better barrier than the other alternatives, so if you are priming to cover nasty odors or something, then I’d use the shellac-based BIN. Likewise, for your application, I’d stick with shellac…it’s slightly better as a moisture barrier, but it also dries very fast…giving really runny knots little chance of affecting the primer as it dries (which could be a problem with the slow drying oil-based stuff).

The Zinsser Seal Coat mentioned by Jerry is essentially the same stuff as the BIN Primer, perhaps a little thinner than the Bin Primer (though that’s just a guess on my part), and clear like typical shellac.

-- jay,

View madts's profile


1873 posts in 2540 days

#3 posted 12-20-2012 09:51 PM

Try Putting some super glue on them. That will seal them and also keep them in place if they are loose.

-- Thor and Odin are still the greatest of Gods.

View LearningAsIGo's profile


50 posts in 2836 days

#4 posted 12-20-2012 10:56 PM

I have Zinsser 123 latex based primer
Cover Stain oil based primer

I have a quarter of a can of bin but it’s been sitting in the basement awhile and I’m not sure if it’s usable.

Can I use one of these?

View NiteWalker's profile


2738 posts in 2777 days

#5 posted 12-20-2012 11:09 PM

+1 more for zinsser BIN. That stuff is amazing.

-- He who dies with the most tools... dies with the emptiest wallet.

View Rob's profile


317 posts in 3187 days

#6 posted 12-20-2012 11:22 PM

Zinsser Bin is definitely the product to use. Get the Shellac based. The Latex stuff is good for general purpose priming but won’t seal the knots

View Rick  Dennington's profile

Rick Dennington

6301 posts in 3395 days

#7 posted 12-21-2012 12:58 AM

If it was me, I’d seal the knots with epoxy….You didn’t mention the type of wood you’re using, but I’d mix up a little dust with the epoxy and fill them it…..good to go…...

-- " At my age, happy hour is a crap and a nap".....!!

View LearningAsIGo's profile


50 posts in 2836 days

#8 posted 12-21-2012 04:14 PM

The wood is dimensional lumber so probably douglas fir or whatever else they make it out of

View kizerpea's profile


775 posts in 2568 days

#9 posted 12-22-2012 12:25 PM

another ZINSSER b.i.n. here ..pine knots…. shellac based primer two coats an lookin good!!!!


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