Strange effect - emulsion on silver spray paint?

[HerrX]

For reasons that I don't fully understand, a 'beautiful' leaf pattern was painted on to the walls of our bedroom. Spray painted. With shiny silver paint. I kid you not. My guess is this paint was intended for art projects or possibly covering repair jobs on the car, but definitely not meant for putting on plastered walls. The 70s have a lot to answer for!

The previous owners, thankfully, had a little more taste and managed to cover up this monstrosity with what looks like bog standard magnolia emulsion.

That's how things were before we started. We stripped three of the walls back down to the plaster (this is how we know the colour and nature of the spray paint...), but decided that with time pressing we would leave the last wall and just sugar soap and paint it.

Big mistake. We can see the familiar pattern of the silver leaves where our new emulsion isn't taking. Whatever that silver paint is, it is working its way through the magnolia and the white undercoat we put on and preventing the matt emulsion for adhering properly.

So... how on earth do I fix this, short of stripping the paint from that final wall? I'm need to get another tin of paint, so I'm wondering weather a different finish/type would adhere better.

Thanks in advance for any tips!

 

[footprints]

Hang lining paper, or use Zinsser Bullseye 123 stain block two coats.