The E-Sylum:  Volume 5, Number 5, February 3, 2002, Article 15

LACQUERING'S BAD RAP.

  Regarding Ron Guth's item on the Milwaukee's Museum
  Cleaning & Lacquering, Dick Johnson writes: "While cleaning
  coins is another story, lacquering coins has gotten a bad rap
  in the numismatic press for years. It is a coating placed on a
  metal numismatic item that prevents toning, tarnish and some
  abuse. Literally, it can preserve the original condition of a
  metal surface if it is applied properly and shortly after the item
  is struck. This was widely done by some real old-time
  numismatists for preservation, but this was before slabbing
  and air-tight plastic containers. (Did they know something
  that has been forgotten by modern numismatists?)

  There are numerous kinds and colors of lacquers but is
  basically a clear shellac. Most trouble comes from
  inexperienced application.  It should be applied as lightly as
  possible but must cover the surface completely.  Since the
  ideal lacquer used for coins is clear, you cannot see it when
  you apply it. Lacquers are widely used in the manufacture
  of better medals. These are often tinted.

  It is best applied with a spray gun (the finer the nozzle
  apertures the better). Since the spray disperses into the
  air, a mask for the operator and a spray booth must be
  used (required by OSHA!). In medal manufacturing the
  medals are baked (to remove all moisture), laid out on
  a wire tray about 12 by 24 inches, and this placed on a
  turntable inside the booth.  One pass of the spray gun
  west to east and back. The tray is rotated 90 degrees.
  Another pass and back. It dries immediately. A tray
  is placed over the medals and the entire ensemble held
  tightly and flipped over. Then sprayed again like before
  (on the opposite sides).

  Inexperienced collectors are tempted to use lacquer
  from a spray can (or worse, brushed, or dipped!).
  Inevitably, they apply too much lacquer and it builds up
  in crevices and goops at the sides of letters and relief.
  Instead of a few microns of lacquer covering the surface
  it is far, far thicker.  This can be seen -- and it's unsightly!
  Thus the reason for the bad rap.

  Incidentally, two petroleum products should be on hand if
  you have a large medal collection: TOLUENE (to clean
  lacquered surfaces) and ACETONE (to remove the lacquer).
  Both are highly inflammable -- you must know what you are
  doing! Caution: after removing the lacquer the surface is super
  sensitive to toning (called ACTIVATED SURFACE) and will
  begin toning within two week's time."

  Wayne Homren, Editor

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