Painting have mould growth.

Brush it off, attending to the front and back of the painting, and air it for a few hours outside. There is more on this on the MITRA website (USA) which I'll try to find tomorrow. Orf to bed now....

Right - a bit more research undertaken.... Take the paintings outside into sunlight, and leave them for some hours. Brush off all the mould you can see on the reverse and front of the painting with a soft brush (you can also use a vacuum cleaner on a VERY low setting, but be careful). Mould spots on the painting itself are not easy to remove once they've dried out, because mould filaments penetrate the paint. However, very, very careful dabbing at the spots with a cotton-bud dipped but not soaked in Iso alcohol, perhaps diluted, might work AFTER you have tried brushing it away and gently polishing the surface: if the painting is varnished, you may be lucky - the mould might just be sitting on the surface of the varnish. If it doesn't work, this is about the limit that a non-professional conservator can do - anything more than that requires the attention of a trained conservator. Better to leave the dried-out mould spots there than rub away at the painting and remove paint. Some paper cleaners - available from Brodgar (I think: if you can't find it under that name, look for websites selling book and paper restoration products) by mail order - eg, Absorene rubbers, remove dirt and mould from the BACK of the painting (if it's on a stretched canvas). I have seen some advice online recommending the use of a tiny drop of bleach in water - the person giving the advice says that very little bleach is needed to kill mould. Personally, I would never approach an oil painting with bleach in any form, no matter how weak it was - if you've seen that advice, I really wouldn't take it: you could destroy your painting, and bleach is extremely bad for cloth fibres. I think you've got a bit of a problem with these paintings, to be honest, but with any luck some combination of the above procedures might at least make them presentable; granted, finding a dry, sunny day at this time of year isn't easy, but get as much of the mould off as you can even if you can't put the pictures outside for the moment; the conservation site I visited recommends wearing a mask, to avoid inhalation of mould spores: I admit that I wouldn't do that, but I had better advise you that you should. In short - clean them as much as you can yourself without resorting to drastic measures; if the paintings are valuable, commercially or sentimentally, take them to a conservator - they're few and far between, but they do exist.