Shellac is the typical sealer for resin from pine knots. Zinsser Seal
Coat is a dewaxed shellac that is packed in a Qt. can about $6.95USD.
Spray shellac is also dewaxed and will seal.

On Wed, 23 Nov 2005 18:31:37 GMT, "CathyLee"
wrote:

I used zinssers on my pine window trim with 2 coats semigloss and i am
starting to see some knot stains coming through. Just installed this
summer.