Keith,

Having been an objects conservator for 14 years and specializing in the
treatment of metals & arms for over 10 years I can offer you some very specific
advice.

Unless the ferrous objects in your collection are displaying active corrosion
or are in an excessively bad environment (e.g. 70% - 100% Rh, and within a
few miles of the ocean) then there is little reason to do anything but leave
these objects alone.

Coating historic and ancient metals is a complex proposition. Most coatings
will not adhere properly unless the surface is "clean" and that cleaning
process can be a quite invovled and lengthy process to undertake and still preserve
the integrity of the metal surface - in terms of finish, history, and any
patinas. If the surface is not properly cleaned then you can actually increase the
corrosion rate - this is most evident in historic brasses that are cleaned
with polishes such as brasso, that contain amonina. The residues left on the
surface can soak up moisture and initiate corrosion and any residual amonia can
cause a corrosion phenomnon know as stress corrosion cracking. The residues
invovled here can be microscopic and still cause damage. If you apply a coating
over such residues you actually provide an easy locii for the coating to
rapidly break down. Another problem is if coatings and applied only partially, and
this is even done sometimes by trained people. A partial coating is often worse
than none because all of the electrochemical forces are concentrated in a
very small area, and this can lead to severe damage, forming localized corrosion
pits. There are also coatings that contain chemical constituents that over
time can polermize, or cross-link. What was once easy to apply may because almost
impossible to remove later on. So you need to have very specific technical
knowledge of what you are applying to the surface of an artifact or object.

Many ferrous objects were "cleaned" in the past by well-meaning individuals
who used products like naval jelly. The jelly contains acids that indeed
"cleaned" the corrosion but it also etched right into the core metal, dissolving any
traces of the original surface.  Many commercial products are made to
aggressively clean rapidly and are not intended for the long term preservation of
something that you might keep in the garage or shed. That sort of instant
gratification that you can buy at the hardware store often is detrimental to musuem
objects and artifacts.

Without seeing these objects and understanding their condition I really can't
offer you much in the way of advice. Are they painted? Are they all iron or
contain components made of copper alloy, wood, or ivory? Are they tinplate?
Have they been treated before? Have things like oils or waxes been applied to
them? What are the environmental conditions? How will they be exhibited?

So these are the sorts of things that go through my thinking and decison
making process when assessing the treament approaches to ferrous metals.

It is not something that I would ever term as "easy".

Cheers!
Dave

David Harvey
Artifacts
2930 South Birch Street
Denver, CO  80222
303-300-5257
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