I was ageing paper for reproduction radio labels. I needed a yellow brown blotchy paper to print the labels on. I would take a quart of table grade cider vinigar and stuff a steel wool pad into it. After a few weeks the pad would desolve completely into solution and I would soak white paper in it, dry it and then iron it. Looked like it was 80 years old.
Never really gave it the rust test.
DG
