How to cover dark patches on painted wood

[Maggie1]

I have just stripped all the paintwork on the stairs and landing. There are a lot of knots in the wood and also some areas where I left the heat gun on a spot for too long and "burnt" the wood surface.
I have applied two coats of Zinsser Bulls Eye 1-2-3 primer and sealer (and stain blocker) but these dark areas are still showing through and I'm not sure if the paint I have for the top coat (Johnstone's Trade Acrylic Durable Eggshell) will cover them.
I appreciate any advice given and thanks in advance for any help.

 

[DiyNutJob]

Maybe you didn't stir the primer properly. There's no limit on how many coats of primer you can apply. Give it a good stir/shake/whatever, and try again. Also, there's no limit to the number of top coats you can apply. If you really want to, you can apply primer, top coat, primer, top coat, etc. The primer is there to stick, and the top coat is there to cover. Things showing through the primer shouldn't be a problem.

 

[Maggie1]

Just curious. How long should I stir the primer for?

 

[Wayners]

Could try 123+ but I'd use zinsser BIN.

Bullseye 123 is not a full range stain blocker. Some minor aged stains only.
The 123+ is better and may work

 

[Maggie1]

Should I just paint the dark areas with BIN?

 

[Wayners]

I'd apply BIN to all off it
Then correct primer for top coat.

See If all is ok before your eggshell goes on

4 coat system.

One bin. One primer and two top coats

 

[Maggie1]

Thank you

 

[DiyNutJob]

Just curious. How long should I stir the primer for?

Stir until tired or bored, or get a child to do it for exercise. Stirring paint that's been sitting at the shop for an unknow amount of time is better than not stirring it.

Should I just paint the dark areas with BIN?

You can do that. Spot repair is a natural part of painting.

 

[Wayners]

Sir until all mixed.

Could be 10 seconds or a few minutes If thick at the bottom of can
Wooden Spoon in drill works well on slow speed