Removing rust from external painted wall

phlogeston

A few years back, I had a loft conversion. The external wall was pebble-dashed to match the rest of the house.

I then painted all the pebble-dash.

After a year or so, a number of rust streaks began to appear from the new render and the rust has now stained all down the painted surface of the wall.

On inspection, it appears that the pebbles have some iron content which has caused the staining.

I am going to dig out all the offending iron and fill, but was wondering if anyone could recommend a good way of either...

Covering the rust so it does not come through any new paint, or
Removing rust stains from exterior masonary paint?

Many thanks

amarg

This might help-

removing rust from stone

nickj_2

try painting with a solvent paint - undercoat or stain sealer