<HTML> <HEAD> <TITLE>Re: [CAUT] Tuning Pin Questions</TITLE> </HEAD> <BODY> I only have expertise in one area here, but I’ll share it.  Bluing is a rust preventative surface treatment for steel.  It was once the most common means of rust prevention, but now is used only occasionally, mainly for gun barrels and tuning pins.  Technological advances have made plating and stainless steel much cheaper than they used to be so they are now the norm, except in applications where those materials don’t work very well – like gun barrels and tuning pins. Regards, Ken Z. -- Ken Zahringer, RPT University of Missouri School of Music </BODY> </HTML>