Hi folks,
Is there a product that «Really» seals Knots in Pine that will be painted? I’ve used oil base primer (1 coat) and 3 coats of Latex paint, both of best quality and months later, Trace of knots started to reappear on my work! I’m desperate!
Any Idea? Thanks
JP Maher
Replies
I have found a shellac based primer will work.
most of the time.
In situations like up under roof sheeting as a porch ceiling finish, the heat will cause the knots to bleed.
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Thanks a lot! I'll sure try that stuff,JP
we do primer, then a coat or two of the shellac based primer/sealer like kilz, then finish coats.
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Thank you very much!I'll go on with that procedure from now on. But just one thing! Why a primer FIRST than shellac primers after?JP
to be honest, I'm not sure, except that this is how I was taught.I do know that primer has more bonding agent than finishing paints, so maybe it has the "glue" to stick but sealers are sold as primer/sealer also so it ought to work either way
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Piffin.
you will find superior knot sealing if you use shellac first then primer.. The reason has to do with the nature of shellac.. it's really thin watery stuff that soaks into the finest crack and seals like crazy.. primer will block some of that ability to seal..
I won't argue against that
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Thinking some more here - we do two coats of the sealer on the knots that look bad - instinctive judgement that they might still want to bleed through. I'm remembering that this is more easy to see and judge when the whole board is already white
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Doesn't matter why really! If it works, it works. Thanks for the tips. It's a pain when a good job suddenly turns into a nightmare! The Pine wasn't dry enough to be painted. But anyway, knots almost always come back till many coats of paint are put on!Thanks again,JP
I have always used alcohol based "Bin"
Works well dries fast (to fast ruins any brush it touches).I think thats the idea,it dries so fast it seals anything under it.
What ever it works.
Thanks,I got a pretty good idea of what the problem is now. I'll try that too.Thanks againJean-Pierre Maher
Québec Canada
alcohol is the carrier for shellac. It is shellac based with alcohol as a thinner/carrier/solvent.Shellac is flakes of partsfrom microscopic prehistoric animals. Those flakes layer down on top of each other as solids and that is why it seals well.
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Piffin,Shellac is actually the secretion of the female lac insect, Kerria lacca.It is harvested by scraping off tree limbs. Child labor at its best.KK
For more detail on shellac, you might want to check out the Wiki entry:http://en.wikipedia.org/wiki/Shellac
Prehistoric ? I believe shellac comes from secretions of the Lac Insect, no?
apparently I am wrong on the origins and right on the flake/solids character istics..Oh well, got my mistake out of the way early this week
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well, got my mistake...
I'm surprised. Is that your first one for the year?
One a week? Maybe one day I'll get to be that good....
Hi Piffin,
I'm pretty new here, and have been enjoying reading your posts. I will definitely investigate Shellac. Any good books?
" I'm pretty new here, and have been enjoying reading your posts. "That's OK, you'll get over it, LOLyou'll notice that there is a large knowledge base here - I call it the mastermind. Somebody will recommend a book
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Works well dries fast (to fast ruins any brush it touches).<!----><!----><!---->
Actually, you can clean your brush with household ammonia - dry or not.<!----><!---->
Ammonia works well for cleaning any BIN drips that may have gotten past your drop cloth.<!----><!---->
Terry<!----><!---->
I just use throw away brushes
Henley,
Don't clean the brush but just reuse it! The alcohol in it will soften the brushes back up and you can reuse the brush!
I never clean my brushes, just let them soak in the shellac for a few minutes and some of my brushes are over a year old!
That let's you spend good money for a brush which helps me be a better painter.
Exactly. Just dedicate a brush to shellac, and don't bother cleaning it. Faster, better for the environment too. Use a taklon bristle brush for shellac. It really makes a difference.
Does it really clean your brushes?
I mean would you use your brand new Purdy?
Does it really clean your brushes?I mean would you use your brand new Purdy?
Honest to God, I do use a Purdy (synthetic) brush for BIN.
I find that when I use a cheap throw-away brush for BIN, either bristles pull out or I get a rough looking finish or whatever.
The point of priming and painting is to provide the best finish I can.
Just to see how well ammonia works on cleaning a brush, try soaking an older brush that has latex dried up in the heel in it. A short time later use a brush comb or a wire brush and see how much comes out. And keep in mind that ammonia works even better on BIN.
Terry
ok ok no more through away brushes. Can't a guy be lazy once in a while?
Have had very good luck with Gougeon Brothers epoxy, maybe overkill, but no bleeds. EDIT: Try your local boaters supply or Gougeon.com
Edited 1/21/2008 7:14 pm ET by rlrefalo
Don't mind over-killing 'cause the knots might kill me soon!Thanks,Jean-Pierre
There is a product by Fast-Cap it is a cyanacuralate(sp?) glue i use the medium viscosity with the activator dries completely in this season in 10 - 15 minutes. It's not cheap , but it works real quick and efficiently so there not a lay up time . For large jobs i would go with west- systems for exterior , shellac for interior. I take any guess work out of it , with those applications.................. Good luck
Thanks,Another trick in my pouch! I need that.Jean-Pierre