Sealing Pine Knots

[efgh]

I've been using shellac to seal pine knots and I've been happy with the results in that the knot doesn't bleed through. The problem I have is that I usually end up painting the project with white paint which doesn't cover the shellaced spots very well. I have to put on at three coats of paint to cover it and even then, it still doesn't look very good. Before anyone suggests I switch to a different type of wood, I use pine because it's cheap and I don't mind covering it with paint. I'm not a big fan of using a hardwood to just cover it up with paint.

Does anyone else use something besides shellac to seal the knots that works well when painted? I know Zinser makes a primer that includes shellac and I've used it before but after a year or so, the knots still bleed through.

My method once sanding is complete is to put the shellac on the knots, sand lightly with 220 grit, then apply latex primer, sand again lightly with 220 grit, then apply latex paint.

Thanks in advance.

[Dave In Houston]

Is this an interior or exterior application? In either instance I would start by switching to an alkyd primer over the shellac. If it's an interior application I always use an alkyd enamel.

[efgh]

It's for interior use only. I prefer latex because of the lack of odour relative to alkyd.

[SonomaProducts.com]

If you are using bullseye shellac out of the can, it is not dewaded and could be one reason paint isn't coveriing well over it. Regardless, look for another product by Zinser called Killz (not sure about spelling). It is a covering primer that I think has some shellac in it. It is also perfect for covering sappy knots and is a white primer paint. I would do one complete base coat of this with maybe a liitle more where you have the knots, then the top coat of paint will be consistent.

If you want to stick with shellac you can stry scuff sanding before you do a top coat. With Killz you can build it up thick and then sand it out to get a very smooth base for your paint, which is really reccomended for any over wood application if you want smooth finish.

[efgh]

I've tried a Zinser primer that had shellac in it and the knots still bled through after about a year. I guess what I'm wondering if anyone has tried a polyurethane like product and got the same results if they had used shellac.

[Dave In Houston]

Zinsser and Kilz are, in fact, two different brands of similar products, ie pigmented shellac. Cannot say about the Zinsser brand but know that Kilz makes a low or no ordor variety. And Benjamin Moore touts this alkyd primer as being "low odor." Benjamin Moore Fresh Start® QD-30 Stain Blocking Primer 202:

[Nova]

is made by MasterChem Industries, Inc. They make eight different types of Kilz Primers:

[Phisherman]

Coat the knots and any resin veins 3 or 4 times. I put up some painted crown molding (on a 18-foot ceiling) that I had primed with a shellac-based primer. It looked great, but after 3 years I started seeing resin patterns emerging. I sanded these areas, shellacked them

4 times, then painted over. It has been 10 years without any bleeding. Some of the (pine) door trim did the same thing. White shades of paint are the worst.

[cselby]

I used aluminum paint (spray bomb) on a stubborn corner that was attracting mildew. Latex paint over that and it hasn't come back in 8 years. Could also use brush on from a small can.

I offer this up knowing you don't want the odor issues, even tho that only lasted 1/2 hr indoors.

Pete

[efgh]

One coat of shellac works well for me. The problem I have is that it usually takes 3-4 coats of white paint to cover the darkness of the shellac so you can't see it. I'd like to use something lighter in colour like a polyurethane but I'm wondering if has the same sealing results of shellac.

[alexy]

While I know that the OP has rejected it, for reasons that may be right for him, I'd strongly second this suggestion. While I agree that an alkyd enamel provides better leveling and harder/more attractive surface, if the OP still wants to use latex as a top coat, I'd still recommend the oil-base primer. At the very least, buy an aerosol can of Kilz or BIN oil-based primer and spray just the knots before brushing on your latex primer. I can't imagine a knot bleeding through shellac + oil-based primer + latex primer + latex topcoat!

[B A R R Y]

Try Zinsser "BIN". BIN is white pigmented shellac.

[B A R R Y]

Not to nitpick, but I think it deserves to be mentioned that there is no such animal as "BIN Oil Based". Zinsser does indeed make an oil based product, but BIN isn't it. BIN is shellac premixed with white pigment.

Details:

[alexy]

Thanks for the correction. I usually buy Kilz, but was intending to mention a competing product not to appear to be promoting one particular brand. Oh, well; my intentions were pure. ;-)

[J T]

Wed, Oct 24, 2007, 4:56pm (EDT+4) [e-mail] (efgh) doth sayeth: One coat of shellac works well for me. The problem I have is that it usually takes 3-4 coats of white paint to cover the darkness of the shellac so you can't see it. I'd like to use something lighter in colour like a polyurethane but I'm wondering if has the same sealing results of shellac.

Well, apparently your one coat of shellac "doesn't" work well. If it did, you wouldn't be asking. I use latex on a variety of my projects. With no problems. I do use good quality indoor/outdoor. One coat usually meets my needs, sometimes two. You may want to try a different brand, and/or better quality. I haven't used shellac in decades, but do understnd it comes in different shades. You might want to buy flakes, and mix your own. Anyway, I think it's more likely the darkness of the knot, and not the shellac, that you want to cover up. I don't recall you saying what it is you paint. If you want viable responses, you need to provide ALL the details, not just a few. You know what they say, "GIGO, garbage in, garbage out".

JOAT "I'm an Igor, thur. We don't athk quethtionth." "Really? Why not?" "I don't know, thur. I didn't athk."

[Ferd Farkel]

messagenews:M5SdndGT7otXzoLanZ2dnUVZ [e-mail]...

Alkyd enamel is the one to beat. Acrylic comes close, might be worth a try if you hate the smell of varnish. Latex is good for rolling onto walls and not much else.

[Nova]

Use a blond or super blond shellac.

[J T]

Wed, Oct 24, 2007, 5:11pm (EDT-3) [e-mail] (Ferd=A0Farkel) doth sayeth: Latex is good for rolling onto walls and not much else.

You've obviously not been keeping informed. That's not the case anymore. Check to see what type of paint most houses are being painted with now..

JOAT "I'm an Igor, thur. We don't athk quethtionth." "Really? Why not?" "I don't know, thur. I didn't athk."

[J T]

Thu, Oct 25, 2007, 12:43am (EDT+4) [e-mail] (Nova) doth sayeth: Use a blond or super blond shellac.

Heh. Even better, drill, or cut, out the entire knot; then glue in a identical profile pine plug. No prob, it's going to be painted anyway. LMAO

JOAT "I'm an Igor, thur. We don't athk quethtionth." "Really? Why not?" "I don't know, thur. I didn't athk."

[J. Clarke]

While I agree with your point, the fact that most houses are being painted with it now doesn't necessarily mean that it's good, only that it's politically correct.

For older houses that have been repainted several times it's a safe choice as well--you don't really know what kind of cheap crap the last guy put on, and latex will go over oil and stick but oil won't go over latex and stick.

I need to strip mine to the bare wood at some point--the paint's peeling but it's not any paint that I applied--the peel is between a blue layer and a green layer and it's been white as long as I've had it.