Should I use Zinsser BIN?

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Rosina

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I want to paint some pine furniture (4 chests of drawers). They are 50 years old and finished with a varnish. I will be sanding them down and was going to spot the knots with Zinsser BIN, sand down a little, and then use a water based primer undercoat followed by a couple of water based top coats.

I have done a test on a piece of plywood to see if the BIN shows through and whether the water based paint adheres ok. I’m not totally happy with the look as I can see the patch of BIN showing through the blue paint.

Do I have to use BIN or would the knots have dried out because they are 50 years old?
 
Rosina, good evening.

After such a long period of time and the fact that the timber is relatively "thin" it should be squeaky dry by now, and any residual resin in the knots will have gone.

Ken.
 
If the bin is white, and you are putting blue on top, you will see white grinning through after just one coat of blue.
 
Thanks very much KenGMac, I think I will give the BIN a miss. Yes the wood is thin and I looked on the other side and the knots look dry.
 
Thanks for your suggestion Chivas 69, but the BIN is not very nice, it doesn't go on smoothly like a paint, so think I'll go with KenGMac's info and just put on a primer undercoat.
 
I’ve just painted some external doors that Had been painted in gloss (years ago).
After a wash, rough-up I used the ‘blue’ can of zinsser... followed by a coat of water based Undercoat then satin... has worked a treat.

The zinsser is a bit watery to paint on, but Provided a good key for the next coats... il be using it again.
 
Thanks for your info Mr Chibs, It’s useful to know how all these undercoats work - I think the blue can is the Zinsser 123 which is water based.

My problem is all the knots in the pine which is why I was considering Zinsser BIN, which contains shellac, apparently the all important ingredient for stopping the resin in the knots from staining the paint. But as I would be using it to ‘spot’ prime the knots and it appears to show through a little, because it’s an odd sort of paint, I’m probably not going to use it.
 
Old wood should have stopped bleeding by now, you can just buy knotting solution, if you use this, try to get the clear one... the dark brown one taken more coats to cover-up.
 
Thanks for your suggestion Mr Chibs. Yes I have seen clear knotting solution, I believe that I have to dewax it if I want to put a water based paint over the top. I have read that I could do that using denatured alcohol which I think is the same as methylated spirit. I've also just realised that some of the knots are a bit bumpy with a few gaps and I'm going to have to use filler on some of these, probably after I've done a coat of primer. Any experience with all this?
 
Car body filler is what I use to fill gashes and splits, followed by knotting solution, then water based primer, undercoat and then paint.

Why do you have to dewax... varnish is not a wax finish?

Are you painting more than one piece?
 
Thanks for the order of procedure Mr Chibs. I read, on a DIY site, that shellac needs to be dewaxed with denatured alcohol before painting over with a water based paint - maybe that is incorrect! I am painting 4 chests of drawers by the way.
 
Thanks Chivas 69. I though I'd start off by sanding down a bit just to give it a matt surface for the paint to grip on to. I wasn't going to try to get every bit of varnish off as I didn't think that mattered as long as all the surface was 'roughed up' a bit for the paint to adhere to.
 
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