Metal polish

Tom Dixon <tom.dixon [at] ngv__vic__gov__au> writes

>I have used Nevr Dull <URL:http://www.eagleone.com/> occasionally
>over many years, but not often or regularly.  Recently I was
>contemplating using it on a fairly continuous basis to polish a
>large gunmetal bronze sculpture over perhaps many years. This raised
>the issue of what was actually in the product.  The manufacturer
>provided a MSDS but this lists the components as "trade secret".
>Further inquiry with the manufacturer revealed only the solvent
>involved was similar to Stoddard solvent and the other chemical
>components were secret.

I had a look at the Nevr Dull MSDS with the same outcome--that it
does not meet the new Australian Standard and has little relevant
information.

That being said, metal polish compositions typically are composed
of:

    Solvent (usually White Spirit ("Stoddard Solvent") or Mineral
    Turpentine, although newer ones may contain dearomatised
    solvents)

    An emulsifier blend (in older systems these we usually oleic
    acid / ammonia blends--newer ones may use non-ionics or oleic /
    morpholine or similar blends)

    Waxes (Good quality products use carnauba or candillia waxes,
    usually with a smattering of beeswax or paraffin wax for
    consistency)

    An abrasive ( this may vary DRAMATICALLY from different
    formulators - bentonites, silicas, diatomites, aluminium oxide,
    rottenstone, etc all have been used--the main thing is to have a
    blend which has some softer material that "grinds down" during
    use. If aluminium oxide is used it has to be very fine--< 20
    micron--to avoid scratching).

    A preservative--variable--formaldehyde, triazines,
    p-hydroxybenzoate esters, hydroxy methyl glycinate and
    methylchloroisothiazolines have all been used and are still in
    use.

In addition to these basic components, metal polishes *may* contain:

    Silicones--as gloss and slip agents--probably fine on metal but
    cause problems on painted surfaces if not removed prior to
    touch-up with new paint.

    Resins--either acrylate or urethane or siloxane to act as
    fillers on the metal surface and for longevity of  the polish.

    Anticorrosive--typically substituted tolytriazoles which form a
    protective monolayer that inhibits oxidation, particularly on
    yellow metals (bronze, brass, etc) and silver.

    Gelling agents--acrylics, bentonites,  natural or synthetic
    gums, carboxymethylcellulose and derivatives or aluminium
    magnesium silicates either singly or in combination.

Products may be either acid or alkaline balanced depending on the
way the chemist has approached the formulation issues.

Depending on the end-use you want to put the polish to some of these
components would be beneficial and other may cause grief
(particularly the silicones and resins).

In terms of handling, most polishes contain sufficient flammable
solvent to be a handling hazard. It is possible to formulate a
polish "free" from flammable solvent (< 10% anyway) and without
silicones. We have done a number of them for special use projects.
The other potential hazard is the dust which may form during buffing
of the polish--if you are working with a large surface and an
automated buff I would suggest a dust mask is appropriate.

If you want any more information I can be contacted via
baheath [at] specsol__com__au +61 7 3265 6311

Bruce Heath BAS App Chem. GD Tech Mgt MBA
Technical Manager
Industrial Cleansers Pty Ltd
Brisbane, Australia


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                  Conservation DistList Instance 17:54
               Distributed: Wednesday, February 18, 2004
                       Message Id: cdl-17-54-008
                                  ***