Wood varnish stain coming through primer

[Iloveangelslices]

Help!

I’m priming my staircase and bannister with wood primer, but I have this terrible yellow stain soaking through that I think may be varnish?

I did sand the surface beforehand using an electric sander, hoping I could avoid this.

Does anybody have any recommendations of a product I can apply over this to stop the yellow seeping through? I want a white gloss finish eventually.

TIA

It's probably the tannin from the pine. Most decorators swear by Zinsser primer and stainblocker.

I'd go another coat of primer.

I’d try stain blocker then another coat of primer - Zinsser is meant to be v good

Thanks for the recommendations everyone. I used Zinsser stain blocker and it worked a treat. Gloss tomorrow 🙂