Sealing knots in PT

[Bernie]

Is it necessary to seal the knots in pressure treated lumber (with shellac, for instance) prior to painting it?

If yes, is shellac the thing to use or will other things also work?

Any help much appreciated.

[Roman]

[Barry in London]

The link at the bottom is the best stuff I've seen so far. Shellac based and covers a multitude of sins! Available at HD, paint stores and probably RONA.

I would imagine this will work too - SealCoat http://www.zinsser.com/product_detail.asp?ProductID=72

Regards

Barry



Zinsser Primer Sealer

[Roman]

To the best of my knowledge its the best out there. Eventually even Zins wont stop knots from bleeding but by the tiime they do bleed through it will be time to re-finsih the PT.

[Bernie]

Thanks Barry and Roman for the replies. I'll check out this Clearcoat stuff. Looks like it might be useful for other applications as well.
Regards.