Painting over wood with knots

[ben67]

I need to paint a new pine doorframe. The wood has lots of knots which I have painted with Knotting solution. Then I have applied a primer on the doorframe, but I have noticed that the knots are coming through and the primer over the knots is cracking.

Was I wise to use knotting solution when I was going to prime the wood anyway.

Also, at this stage should I apply an additional coat of primer over the knots and hope that this will provide a good enough base for the final coats of paint - I intend this to be an oil based silk paint.

 

[JohnD]

For knotty, resinous or burnt-off wood I prefer an Aluminium Wood Primer rather than knotting - you can do the whole door in this, it comes out greyish not silvery.

Might just be a personal preference thing.

 

[ben67]

I take your point John, but that would be OK if I was starting from scratch.

Is it feasible to put a layer of aluminium primer on top of the original primer I have already applied.

 

[Growler]

Lightly sand affected areas with 400 grade wet and dry, touch up with your primer/uc and carry on with your final coats.

 

[Nige F]

I`ve bin using B-I-N white shellac wiped it on with a rag over some knotty wood then primed

 

[Zampa]

Stick another coat of knotting over the top of the others then carry on painting.

Are you sure its the stains from the knots or just where the paint hasnt soaked in quite as much on the knots...it can give a similar effect...knots normally take weeks maybe months to bleed through paint.

 

[ben67]

No it is not the bleeding from the knots that is coming through. We have applied knotting solution to prevent that. It seems that the primer has not taken properly where the knotting solution is.

We will try one or two of the ideas offered.

Thanks

 

[Third_Eye]

No it is not the bleeding from the knots that is coming through. We have applied knotting solution to prevent that. It seems that the primer has not taken properly where the knotting solution is.

We will try one or two of the ideas offered.

Thanks

What make of Knotting Solution did you use ? And what make of Primer did you use ?

 

[tonygerm]

sounds as if you have used the knotting correctly,circles and cracks need filling ,rub down flush and of u go. uc x2 glossx1 rubbing down betwen coats.jobs a good one.

 

[ben67]

I think I have identified the problem. I have been using a water based primer on top of the knotting solution (Blanchards). I have now rubbed it down and used a oil based primer. This seems to have done the job.

 

[Belrose]

This has been a very interesting exchange. We recently bought a house with knotty pine everything........... Well, no, not the sanitary ware, but just about everything else. Before the subject is closed I would like to mention that LIBERON make knotting that is clear/slightly white. Not many people seem to know about it. I am convinced that the usual dark coloured knottings grin through after a while so just love the white stuff. Seems absolutely fine where we have used it so far.

 

[Third_Eye]

I think I have identified the problem. I have been using a water based primer on top of the knotting solution (Blanchards). I have now rubbed it down and used a oil based primer. This seems to have done the job.

Yep, when using water based primer/undercoat over an knotting solution then this can cause the problem you suggest (even years later). I have found YOU MUST use an Oil Based Primer over Knotting.

 

[robopenshaw]

Hmm... I too have movedinto a house that is vritually pine everything!

Previous owner varnished all the pine witha single varnish coat.. This has raise the "pile" and the doors are dead rough now...

So I'm planning on rubbing them down with the orbital sander until smooth, the white gloss over the top of that!

Do I need to add knotting solution here? Or will teh varnish keep the sap/colour at bay?

Rob

 

[Third_Eye]

Nope it will pass through the varnish. If only one coat of varnish has been used, then just apply an knotting solution over that.

 

[bobajobdeb]

This has been a very interesting exchange. We recently bought a house with knotty pine everything........... Well, no, not the sanitary ware, but just about everything else. Before the subject is closed I would like to mention that LIBERON make knotting that is clear/slightly white. Not many people seem to know about it. I am convinced that the usual dark coloured knottings grin through after a while so just love the white stuff. Seems absolutely fine where we have used it so far.

Thankyou for suggesting liberon - I will purchase it off ebay - my knotts have just started seeping through - and will have to start again