rust showing through paint

[Robert]

Hi,

Some rust spots have appeared on my window sill. I am sure these must be the nails heads. I can imagine some condensation may have wet the sill but I am surprised the nails have rusted. I sanded it back to the wood and painted with primer and undercoat that were both solvent based. Shouldn't they have kept the water out? The top coat was that new Dulux water based gloss (yuck!). What is the best thing to paint over the nail heads with to stop the rust stains coming through again?

Thanks in advance. Robert.

[The Natural Philosopher]

knock em under the surface and fill with car body filler.

[Tabby]

use oil based gloss, not water based

NT

[Spamlet]

Or any wood filler. Before you knock them under the surface, check what might be on the other end. Doing window frames last year, I found the nails lifted the paint on the inside when I knocked them from the outside. You might end up having to knock them through, snip the end off and then knock them back and fill both ends. Also fiddly were star shaped pins in the corners of the windows themselves: but they seem to be aluminium.

S

[Cash]

Use knotting and fill the holes with a non-water based filler.

As a matter of interest, what filler did you use before painting?

[Robert]

But I did use oil based primer and then oil based undercoat, so shouldn't these have been sufficient waterproofing?

[Robert]

I didn't. These are very small nails, pins you might call them, and I don't remember seeing them when I painted. They look so small I can't see what use they have. They are at the window edge of a bay window. So no, I didn't use filler, I just overpainted them. It looks as though I need to knock them deeper with a pin punch, fill, and overpaint.