Q. I have just finished the fitting-up of a double boiler, and while I work with fine metal and am particular, the owner recommends burnishing the joints. Can you give me any information how to do it? He wants them to look like silver.

A. You may burnish a joint with any smooth and round steel burnisher, first carefully removing any roughness with a rasp and file. If you succeed in getting a smooth, bright surface, which is exceedingly difficult on such soft metal, you may then coat it with white varnish to prevent tarnishing. On the whole, we do not think it will improve the appearance of your work, while it may convey the impression the plumber was not capable of wiping a good joint, and that he trimmed it into shape.