sealing knots on hard wood

[andrewaaa299]

Hello
I am having new sash windows installed. These will be made of hardwood. I wondered whether knotting solution should be applied to hardwoods to stop the knots from releasing sap. Or is it a case of only soft woods requiring knots to be sealed?
Thanks

 

[karun]

no you dont need to use knotting solution on hardwood but make sure you use a good primer like an aluminium hardwood primer.

 

[andrewaaa299]

thank you very much. Out of curiosity, what are the risks / pitfalls of usuing just a regular wood primer in this scenario?
thanks

 

[dcdec]

a regular wood primer will have very poor adhesion, it is essential to use aluminium wood primer or similar.

 

[karun]

I would very highly recommend using an aluminium wood primer. As im sure you know sash windows are a sizeable investment and the use of an aluminium primer will significantly increase the life of your windows. As it contains aluminium pigment, the primer has far better resistance to moisture than an ordinary wood primer. This not only protects the wood but stops the wood from swelling as a result of a high moisture content.