[vinny2256]

Hi, I've noticed over the past few years that holiday homes beside sea sides in donegal, ireland have become coated in a somewhat red layer (with a ferrate hue).  The walls are painted with white emulsion paint and are pebble dashed although the latter has most likely got nothing to with the matter.  Salt from the sea is definitely thrown up into the air from the sea into the rain so perhaps a certain chemical in the paint is reacting with the Na+ and/or Cl- ions?  I'm unaware of the chemicals in the paint but because the compound is coloured I've thought it more than likely that the precipitate contains a transition metal or much less likely contains a chromophore i.e. is organic based.  I've also considered the possibility that an insoluble salt has formed as I applied vinegar to the precipitate on the walls sparingly to notice a change from a red ppt to a bright orange ppt.

So it's definitely not organic based when i come to think of it. there could also be a chelating reagent in the paint which reacted with the ions in the rain water from the sea.

Mainly I am led to believe the red precipitate with its reddish hue is an insoluble salt that has formed between one of the salt ions with a substance in the paint.  

Can anyone verify this for me or give me a few ideas?
Thanks vince