Will Zinsser Bulls Eye 123 Cover Knots?

We all know that Zinsser Bulls Eye 123 is a great primer and stain covering paint, but how well does this water-based paint cover knots?

Will it make a knot disappear forever or will the resin from the wood soon begin to bleed through your paint? Well, there is only one way to find out, test it!

I grabbed some Bulls Eye 123, found some wood with some knots, and then did a bit of painting and studied the results, let’s have a look, shall we?

Painting Pine Skirting Board With Bulls Eye

The first test will be painting over some raw, unprimed pine skirting board. I had a dig through my sample pile and found the one with the biggest knot I could.

The only thing about this test is that this sample is quite old, so it is not that resinous anymore. This first test will be more about the colour blocking ability of Zinsser 123.

I have another test later to see how well it blocks the resin from a knot coming through.

Here is our sample to be painted, our Zinsser Bulls Eye 123, and a paint roller. I am just using regular old white Bulls Eye paint.

So here it is straight away after painting, you can see that the Bulls Eye 123 has done a really good job of colour blocking the knot and you could easily give this a quick sand and apply your finish coat of paint.

But will it keep the resin from this knot sealed in and not let it bleed through? As I said previously this is quite an old piece of timber so the resin has probably dried out in it quite a bit.

But I will still leave it and see if there is any bleed-through but keep reading as I have a better piece of wood to test resin bleed-through with coming up!

So here is that same sample after two weeks, nothing has bled through so far!

Does Zinsser 123 Seal Knots?

With my first test being more of a colour block test and not a knot bleed-through test I decided to paint something different, something with a lot of knots.

I have this Ash flooring left over from another project, it is still fairly fresh and I know that the knots will bleed through paint easily after trying to paint a bit myself, so how will the Bulls Eye fare?

For this test, I decided to split the wood up into three and give them different coats, one coat, two coats, and finally three coats.

So, running from right to left we have 1 coat of 123, 2 coats, a little slither of 1 coat again, and then 3 coats. This way we can see how the three coats compare.

What you can see straight away from this is that one coat wasn’t enough, this sample definitely needed two coats of the Zinsser Bulls Eye.

But did it seal the knots and stop them bleeding through? Let’s have a look.

Along the bottom of the one coat sample, there is a lot of yellow bleed-through from the wood underneath. You can notice this in the photo but trust me, it is a lot more visible in real life.

The second coat seems to have stopped this, although it is slightly visible, Let’s see if it comes through anymore with time. Check back for an update!

Conclusion

Yes, you can paint over knots with Zinsser Bulls Eye 123, I would recommend using two coats of the primer as one coat doesn’t always seem to be enough to block the knots from bleeding through.