The best method of cleaning a plaster bust when it has got blinded by the finer markings getting dulled with dirt, is by careful scraping. If the whole figure is simply stained, or presents a dirty appearance, the best way is to give it a coat of knotting - a fine varnish that may be bought from any house painter - and, when this has become thoroughly hard, paint the whole with whitewash, adding a little glue to keep it from rubbing off too readily. Whitewash is preferable to paint for the reason that when the former becomes soiled it is easily removed by soaking the bust in water. The water will soften the whitewash, but leave the varnish underneath intact, thus making it possible to retain any delicate modelling there may be, and preventing the finer parts from getting filled up as they would be if a succession of coats of paint were applied. To attempt to wash the figure would only be to further rub in whatever dirt there was on it.