[CR]Removing chrome-plating from silver-soldered components

(Example: Framebuilding:Tubing:Falck)

From: "Norris Lockley" <norris@norrislockley.wanadoo.co.uk>
To: <Classicrendezvous@bikelist.org>
Date: Mon, 29 Aug 2005 22:02:45 +0100
Subject: [CR]Removing chrome-plating from silver-soldered components

Depending on the state of the chrome-plating ie pretty well worn off, and on the skill of the polisher, it is sometimes possible to buff off the remaining plate with fine aluminium oxide grits. The usual way to remove plating according to the company that does my plating is to place the item to be stripped into the acid bath and to reverse the polarity of the electric current. We can all tell horrifying stories of cable eyes being eroded away, of holes appearing in tubes when the current has been too strong, but in the hands of a skilled craftsman no harm should be done.

The question of the acid eating away the silver solder is an interesting one, and I am not convinced that it would be affected. Some long years ago I taught silver-smithing and jewellery-making. At the time we used to etch decorative designs into the students' work using acid mordants. All of our silver solders on the standard practice work in copper, nickel silver and gilding metal were from the Easy-Flo range made by the Johnson-Matthey company.

I recall that on the medium range and low temperature solders ie those running from 620 to 635, and from 608 to 620 range, we often had problems etching away the joint lines in the workpieces..and that they were totally unaffected by the acids so that very fine lines stood out above the surface of the etched-away fields.

I took the matter up with the technical guys at J-M's and received the amusing reply advising me that they had concluded that "...my problem was probably insoluble."

The acids we used were either nitric or sulphuric diluted to a strength relevant to the rate of removal of metal and the texture required. They were almost always used cold or slightly warm. No electric current was employed.

Silver solders as used on bike frames vary little from those used on the type of silver-smithing I described and are usually alloys of copper, zinc, silver and, occasionally cadmium,. In theory the solders should be "etchable".... but J-Ms couldn't explain the problem.

Whether the addition of an electric current into the equation has any bearing on the "etchabilty" of solders I am uncertain

Not sure that this helps at all...Any one out there got a scientific explanation ?

Norris Lockley..disolving into uncertainty..Settle UK