knotting solution

Wrong kind of knots?

Obviously knot a good product. Brian

"Show through" as in blister and ooze resin or just slight discolouration in a pale paint?

A good coat of shellac perhaps. That's all (decent) knotting solution is.

No blisters or oozing, just a brown discolouration on white paint.

What colour is shellac? Is it what gives knotting solution it's brown colour?

I found I had a tin of the ronseal in the garage. I must have bought it to try and forgotten about it. It is water based a white, which is why I wonder whether it is something other than shellac. The blurb on the tin talks about advanced polymers etc. but that could just be the marketing department talking.

I have tried some on the skirting board and architrave; I'll let you know if it works but you will have to wait three years ;)

yes. Think French polish. (shellac + methylated spirits)

Shellac bleaches well, hence the pale polishes and sanding sealers. It also comes in various shades, garnet being the darkest, almost purple colour. Nothing water based is going to seal knots BTW

I'm wondering about not bothering with knotting solution in the future and using aluminium primer for everything instead!

I don't know how resistant that is to the resin that bleeds out of knots

Oh, perhaps I've got that wrong then, I thought it was supposed to stop knots. I thought it had the advantage of being a knotting solution and primer all in one coat, and it's solvent based too. IIRC water based primers can raise the grain. TIA

You may be right. When I said I didn't know.....:-)

any time I have used knotting solution it has been a dark brown colour ... what you are doling is putting shellac over a knot to stop the know bleeding.