Paint won't stick to exterior wall!

Zebbedee

I stupidly painted my exterior plastered walls with an unknown bucket of paint that I found. Have no idea what type it was as I got rid of the empty bucket.
Everything was fine until I repainted it a few years later with a good quality sandtex exterior emulsion and then the paint started bubbling and peeling off on the north facing wall only every time the wall got rained on.
I wire brushed off the loose bits and repainted with more sandtex.
Same problem again, it's ok for a couple of months and then starts bubbling off and loose bits fall off with the wind.
It appears that the unknown paint is the problem. It has a very slippery surface and no paint will stick to it even when heavily keyed with wire brushes.
I have power washed off all the sandtex exposing the unknown paint.
Is there any sort of sealer or primer I can paint over the unknown stuff that will stick to it and then I can repaint over with exterior emulsion?

BobLeeSwagger

Think you need something like this to mix with the paint. http://www.woodiesdiy.com/Product/Owatrol-EB-EmulsaBond-25L/11117/1.1.10.3#.Udnt1PnVCQc
Its dear but I know of a chap that has used it recently and it has done a great job.

cheif kaiser

Sounds like you may have used an oil based paint and the water based paint on top is just not sticking. You could try priming with E.S.P (easy surface preparation) it's supposed to be very good but whether it is designed for exteriors I don't know but you could always email and ask first - http://www.igoe.ie/esp-painting-shiny-smooth-surfaces

michael999999

Give it a few coats of stabilising primer. Then 2 good coats of weathershield.

The EB emulsifier mentioned above is only for use on dusty surfaces. And the ESP is used for painting fitted kitchens and fireplaces, that have a non porous/shiny surface to key to.

boatbuilder

michael999999 wrote: »

Give it a few coats of stabilising primer. Then 2 good coats of weathershield.

The EB emulsifier mentioned above is only for use on dusty surfaces. And the ESP is used for painting fitted kitchens and fireplaces, that have a non porous/shiny surface to key to.

Um I think you've got that backwards
Stabilising primer is only for dusty surfaces. I wouldn't use it in this case.
EB is used to provide a grip to paint on almost any surface inside or outside. It even sticks to glass and varnished surfaces.

Zebbedee

Thanks to all who replied.
Looks like the ESP stuff is the one I need as I have a very shiny surface to paint over.