Emulsion over Brummer Yellow causing bubbles

[RigidCollision]

HI,
Bit of a strange one this. I am building a model railway and am putting a base coat of brown emulsion on it. The board is thick plywood. Where the screw holes are I have used Brummer Yellow to fill. when I cam to paint it all was ok apart from a few of the filled areas. Some of them appear to be causing a reaction with the paint because it is bubbling on the area where the Brummer is.

any ideas what could be causing this and how I can patch fix it without stripping the board right back to wood and starting again?

Regards

 

[footprints]

Hi,
Only guessing here but is there any chance there was oil or grease of some sort on the filling knife?
I would have a go at scraping off the bubbles, wipe with white sprit (on a cotton bud if it's a very small area) then when dry lightly sand to give a bit of a key, spot treat with wood primer (might be best to use an oil based one if you have any) then try your topcoat again. Just try one first to see how it goes.

Hope it helps,
footprints

 

[RigidCollision]

Good point about the possibility of grease, Unfortunatly I don't believe that was likely. I will take your advice and clean, prime and repaint to see what happens. I was thinking along those lines originally but was unsure about the Brummer (I might have been told that I was an idiot because it is not designed to be over painted directly with emulsion ). if there is nothing obviously daft about what I have done then I will go ahead this evening with a scientifically controlled experiment.

I will post back my results...

Regards