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Plating

Why does tin and zinc plating blister on 12L15 low carbon steel?

Pat McKinney
Senior Manufacturing Engineer - Glenolden, PA, U.S.A.
2004

That was pretty vague, Mr. McKinney.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2004

First of two simultaneous responses --

It is the "L" which means "leaded Steel". Under a 20X loop you can see flecks of lead unless it has been smeared by the machinist. Most job plating shops do not understand that lead on the surface forms an insoluble salt with the prep acid in their line: HCl and/or H2SO4.

The only way to get reliable adhesion on leaded steel (or leaded brass)is to dip in 30% Fluoboric Acid and then enter the plating cell "hot" (make contact BEFORE YOU GO IN).

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

2004

Second of two simultaneous responses --

The L is for leaded. That is what makes it cut better. The price of this easier machining is the requirement to have the surface lead removed prior to the plating tank. A dip in fluoboric acid tank is the common cure.

James Watts
- Navarre, Florida
2004

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