using acrylic paint over wood knots

[norbellini]

I have a fire surround to paint in white Using good quality acrylic wood primeras a first coat The surround was previously Polyurethane varniished I have machine sanded back to wood but have three knots that that i am worried about They a re not bleeding or sticky any suggestions thanks

 

[Gerrydelasel]

Most people recommend Zinsser BIN for this.

 

[geraldthehamster]

Knotting compound?

Cheers
Richard

 

[diy lou]

I used Zinsser BIN on a very knotty pine door, dabbed over the knots and then a full coat over the lot (as it was varnished and you don't need to sand if you use this as an undercoat) So far no knots have bled and as the top cpat was white I think I would have noticed them by now! So can recommend it.