# Alternative to knotting liquid required...



## rafezetter (1 Sep 2017)

I've been asked to make a bespoke bath side panel; to basically sort out a bodge of the person who fitted the bath neither level front to back or side to side, so the bath panel it comes with doesn't fit, and it's all been tiled in so no adjustment possible.

I'm going to use pine T&G from wickes (already bought) but being cheap wood it's covered in knots. Rather than using knotting one by one, is there an alternative that will seal them prior to painting, as I really don't want them to bleed through.

Do you think sanding sealer might be enough to do it (which I have) or should I get some cheap shellac?


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## ColeyS1 (1 Sep 2017)

Just use knotting,that's what it's designed for. Or aluminium primer ?

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## Eric The Viking (1 Sep 2017)

[As Coley - both of us having an early breakfast!]

Knotting is pretty economical. I still have half a bottle left over after doing the floorboards and 10" skirting in our bedroom. 

You can also use aluminium primer, but in my experience it doesn't work quite as well (as knotting - otherwise an excellent primer) and it is quite expensive. It is very good for controlling mould and fungus though in damp situations, so I use it on skrtings (our place is old and fairly damp). 

The proper stuff is particularly good for "dead" knots, the ones that have already started to shrink and which otherwise go loose over time. If you are in Bristol presently, Mogfords in WoT carry it in sensible-sized bottles for small jobs.

In this context, given the stock is probably barely better than horrible (I once bought some wood from Wickes!), I would use both, on both sides and the cut ends. Treat the knots themselves with knotting then two coats of Aly primer all over, especially the board ends, denibbing and flatting back between coats. That will make it as stable as you will probably get it, and stop anything coming through or falling out.

Flatting back the actual knotting can be a pain, especially if the wood is resinous - it's a mechanical barrier for the resin, and a thin glue for the dead knots. You are essentially removing it again by sanding. I don't know of a magic bullet - once you break through, the paper instantly clogs and smears, and you're almost at square one again. 

Acetone or meths (or that thinner in tins from Lidl) seems to clean up the resin, bit it also dissolves the knotting! I've settled for a very slight ridge around the knotting patch (spread well past the actual knot), which can be feathered in with subsequent layers. 

I know your finishing is excellent! The Aly primer can be annoying in that it shows through thin or patchy paint, but if it's to your usual standard there won't be a problem. And it does seal well if it's thick enough, so even in a bathroom things shouldn't move around too much.

E.

PS: if you are in Bristol and feel like a trip to Lidl today, TXT me - Southmead didn't get its tool delivery for yesterday, meaning going to one of the others :-(


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## Rorschach (1 Sep 2017)

Zinsser BIN being a shellac based primer should do the job.


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## cowfoot (1 Sep 2017)

Zinnser BIN or Coverstain (most of the decorators I know are using the latter as an all-purpose primer/undercoat nowadays).


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## stuartpaul (1 Sep 2017)

Rorschach":1ogf4boo said:


> Zinsser BIN being a shellac based primer should do the job.


I can also vouch for Zinsser BIN having painted a load of cheap cladding with plenty of knots a few years ago. No sign of any discolouration even now. It is expensive though, - circa £50 for 2.5 litres when I bought.

If it's just a small panel shellac would work (and is cheaper!) but will you need an oil based undercoat afterwards? Not sure, never painted over shellac!


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## No skills (1 Sep 2017)

If possible spend out on the zinsser - a couple of coats should do the trick (wipe the knots with spirit first) and the bonus is you'll have some left over for other projects. I've only used BIN an not cover stain so I can't say if ones better than the other.


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## Woody2Shoes (1 Sep 2017)

I think that knotting solution is basically just shellac - on that basis any shellac-based sludge should do. Also +1 for ali primer.

Cheers, W2S

PS I have a whole house painted by someone who had no idea about knotting - probably the joiner's apprentice - all the doors, architraves and skirtings are pine and covered with dirty brown stains a bit like tobacco.


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## cowfoot (2 Sep 2017)

Woody2Shoes":1pcbpvpg said:


> I think that knotting solution is basically just shellac - on that basis any shellac-based sludge should do. Also +1 for ali primer.
> 
> Cheers, W2S
> 
> PS I have a whole house painted by someone who had no idea about knotting - probably the joiner's apprentice - all the doors, architraves and skirtings are pine and covered with dirty brown stains a bit like tobacco.



Sounds familiar.
The big firms get a crew in to bash them out as quickly as possible for the lowest cost.
Then, if you're lucky, a clerk of works turns up and starts on a snag list longer than the encyclopedia, which then gets passed on to someone who'll kiss his teeth and ask why he wasn't paid a decent day's money to do it properly in the first place.


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## rafezetter (3 Sep 2017)

Thanks for the replies - one of the reasons I had sort of discounted the knotting is because of previous experience of the raised sections Erik mentioned. I'm having to do this job on a very tight budget, so the zinn is out, I guess it's ali primer then.

Edit: ali primer is almost the same price as the zinnser, and this really is a shoestring budget basically little more than a favor for a friend, so .... how far can I thin out bought knotting before it becomes useless? The stuff I have seems pretty thick.


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## ColeyS1 (3 Sep 2017)

Your budget will be out the window if you have to do the job twice. Pointless trying to cut corners. 

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## Phil Pascoe (3 Sep 2017)

Woody2Shoes":xcge1mja said:


> I think that knotting solution is basically just shellac - on that basis any shellac-based sludge should do. Also +1 for ali primer.
> 
> Cheers, W2S
> 
> PS I have a whole house painted by someone who had no idea about knotting - probably the joiner's apprentice - all the doors, architraves and skirtings are pine and covered with dirty brown stains a bit like tobacco.



An ex girlfriend's parents bought a house that was built in the early '70s. A guy I worked with several years after told me his brother had worked for the "decorators" who did the estate. They were on a price and in a hurry so nothing was knotted, primed or even undercoated - it was emulsioned then glossed.
I had no reason to disbelieve him - when the sun was hot you could watch the resin from the knots running down the paintwork. It made a hell of a mess of your clothes if you rubbed against it anywhere.


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## Jacob (4 Sep 2017)

No point in looking for an alternative to knotting. 
It's cheap, effective, quick and easy to apply, very quick drying, but more than anything it is one of the best possible primers for most paints and is extremely durable - often the last thing left after all the paint has been weathered off..


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## PUtcvNqa (5 Sep 2017)

Titebond III works well on knotting
(if you have it and don't want to get Zin Bin)


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## rafezetter (5 Sep 2017)

Jacob":1arcg2xs said:


> No point in looking for an alternative to knotting.
> It's cheap, effective, quick and easy to apply, very quick drying, but more than anything it is one of the best possible primers for most paints and is extremely durable - often the last thing left after all the paint has been weathered off..



It wasn't so much not wanting to use it, I've used it lots, but it was the sheer number of knots etc in the cladding, they were clearly smaller trees harvested with dozens of knots and even some heartwood(?) on a 2.4 plank; that and in the past I've always had to load several layers of primer on top just to mask the visible areas where it's been used.

I took the advice of not cutting corners and shelled out for some Zinnser BIN. Well, what can I say it's great stuff! Goes on well, covers and layers up well too, I did 3 coats as I didn't want to come back to this down the road and to give me some rubbing back leeway. Won't get the money back but it's saved me some time and opened my eyes, I think I'll be using this more often for painting pine.

Thanks chaps.


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## Phil Pascoe (5 Sep 2017)

There's your lesson - buy better timber, it's cheaper in the end.


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## rafezetter (5 Sep 2017)

This is true, when budget allows. It's funny - I have a stash of T&G that Dave the builder salvaged from a kitchen renovation that must have been put up in the 60's or 70's; having just looked at a few boards it's 90% clear and TWICE as thick.

This lady is a friend... but she weren't havin' that for a bath panel (hammer)


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## Bodgers (5 Sep 2017)

Anybody else think that the knotting stuff is a "treatment worse than the disease"?

I recently bought some made to measure softwood garage doors (I was too lazy to make them myself) and it was recommended to me to slap some of this stuff on the knots.

I am four coats of brilliant white Ronseal Weatherproof paint in (two primer, two top coat) and I can STILL see the brown knotting compound...which is kind of what it is supposed to be preventing in the first place...



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## Jacob (5 Sep 2017)

I'd blame the paint. Knotting has been in use for hundreds of years without being a problem.
Ronseal Weatherproof is water based apparently. I wouldn't touch it with a barge pole!
NB just one coat of Allback Linseed oil paint is just about dense enough to cover almost anything, two coats definitely.


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## Bodgers (5 Sep 2017)

Jacob":18v1g642 said:


> I'd blame the paint. Knotting has been in use for hundreds of years without being a problem.
> Ronseal Weatherproof is water based apparently. I wouldn't touch it with a barge pole!
> NB just one coat of Allback Linseed oil paint is just about dense enough to cover almost anything, two coats definitely.


I hear you on the paint. It was the best waterbased I could find. Oil based paint drives my Asthma into overdrive and the clean up on waterbased is much easier.

I suppose I just need to layer up until it has gone.

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## Jacob (5 Sep 2017)

Bodgers":ywtzf21y said:


> Jacob":ywtzf21y said:
> 
> 
> > I'd blame the paint. Knotting has been in use for hundreds of years without being a problem.
> ...


It's the solvents not the oil. 
Another of the many advantages of linseed oil paints - no VOCs. To be realistic there must be a tiny trace of something as you can smell it, but no solvents and/or other VOCs. And you can clean up in soapy water, or leave brushes in oil for a very long time, if well covered.
I wouldn't be surprised if Linseed was good for asthma!


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## rafezetter (5 Sep 2017)

There's a trick used by scale model makers that might apply for some paints, if it looks like they don't seem to have enough pigment to give you opaque coverage - white and yellow are the two colours most prone to the base colour showing through. Obviously for scale models you can't just keep slapping it on or you'll lose the detail so they add just a few drops of black to the mix though obviously we are talking small volumes here. It hardly changes the colour, but gives enough opaqueness to block out the base.

Some people go as far as grading - from grey prime to 30/70 white grey - 50/50 grey white 70/30 white grey - then just the few drops at the end; this is where spraying really shines.

5 coats - primer, 2 undercoat, 2 topcoat isn't that big of a deal especially for outside wood.


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## Jacob (5 Sep 2017)

rafezetter":31eg21or said:


> ....
> 5 coats - primer, 2 undercoat, 2 topcoat isn't that big of a deal especially for outside wood.


Linseed paint you can get away with one coat oil followed by one of paint. But two is better. 20 years down the line and you might have 5 coats but it goes on thin so no problem.


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