In re-painting wooden structures disfigured by the marks caused by iron nails having turned rusty, first rub out the rust marks with sandpaper, getting as much rust as possible off the nail heads; then with a small brush worn down to a stump rub well in around each nail head some good oil varnish. When quite dry, apply the paint. The above method will check the rust to a great extent, but it will still form in the holes against the wood.