Conservation can be quite costly. A $16,000 contract was recently awarded for the conservation treatment to the historical bronze statue of Sir John A. Macdonald in Kingston by traditional art conservation methods. Whether heat stripping, applied artificial "patinas" and waxes are effective in such a severe roadside placement is beyond the scope of this paper.  No one is awarding expensive contracts to preserve the artillery pieces and military vehicles used as monuments throughout the country. Even if they were, they would be ineffective, for the reasons previously stated. Namely, that their demilitarization by welding together all their parts makes effective preparation for repainting impossible.

Corrosion prevention with CPCs
Corrosion prevention compounds (CPCs) are fluids that can both prevent new corrosion sites from forming and, more importantly, suppress any corrosion that has initiated. CPCs are typically used as a post-production treatment to provide cost effective, temporary corrosion protection and to control existing corrosion on any metals. There is a wide range of commercially available CPCs that are ranging from water displacing to non-water displacing soft film and water displacing to non-water displacing hard film (1)

The exact compositions of CPCs are not known due to their proprietary nature. However, information contained in the Materials Safety Data Sheets (MSDSs) reveal that they may include (i) an oil, a grease or a resin based film former, (ii) a volatile, low surface tension carrier solvent, (iii) a non volatile hydrophobic additive and (iv) various corrosion inhibitors or surface active agents. The water displacing CPCs act by spreading across surfaces, into cracks and crevices where they displace any moisture present, leaving behind a residue to act as a further barrier after the carrier solvent has evaporated. The hard film CPCs dry to a waxy or hard resin like finish after application and provide a barrier film to corrosive environments.

The specific CPC, Rust Check, used in the present study has been used successfully in the
automotive field for over 25 years in Ontario. With a low viscosity and a petroleum base, this particular CPC also contains several corrosion inhibitors, a non-acidic penetrant and a creeping agent. Its proven ability to penetrate into the tightest seams and crevices lets it get to the root of the problem. When applied along the crevices of a fused parts cannon, you can see it quickly enter the seam. Applied over an area of surface corrosion, it is apparent that it readily penetrates the oxide layer. The military gunners, who used to lavish attention on the guns with a frequent layer of gun oil, know that this is what the piece needs, i.e. regular oiling with an effective CPC. Application methods of CPC to monuments.

The CPC treatment is simple and inexpensive. A light film of the CPC can be applied by brush, wiping on with a cloth impregnated with the CPC, by aerosol can, or on larger units by a commercial air powered spray unit (Figure 9) as used in the automotive rust proofing centre. The spray unit and the drum of chemicals are mounted in a truck and powered by either a Scuba tank for medium sized pieces or by a towed compressor unit when treating large or numerous pieces. No particular preparation is required.

For outdoor spraying, a NIOSH approved oil mist mask, as worn when spraying indoors, is recommended. Gloves are worn for comfort, as the aerosol cans or air powered spray guns quickly get cold. The CPC is applied paying particular attention to laying a film along all joints, seams, welds, bolts and rivets (Figure 10). After treatment, any excess fluid should be wiped up with a cloth
or paper towel. It is also recommended to avoid using any detergent on the piece for a minimum of 48 hours.

Treatment of outdoor monuments
The City of Kingston gave permission to treat their outdoor military monuments and monitor results with corrosion coupons in August 2001. The Canadian Forces gave a similar permission for the Howitzer gun and Sherman tank at the gate to CFB Kingston on 10 Sept. 2001, and the Royal Canadian Horse Artillery (RCHA) club agreed later. RMC accepted a similar offer late in the fall of 2002, and these monuments are being treated yearly. The pieces in and around Kingston, Ontario have been treated for five years and will continue to be treated annually as a community service by the sponsoring company.

In August 2001, CPC was applied to the severely corroded Boucher Park WWI 77 m. m. field piece (Figure 11). This piece exhibited crevice corrosion between all fused parts, e.g. between the breach block and the breach, at all bolts, and in between the numerous parts that had been welded together to make it a monument. Galvanic corrosion was seen where dissimilar metals (brass and steel) were in contact. The barrel slide was severely corroded and had rust perforation in several places. The surfaces overall had a deep brown surface corrosion and almost all traces of the original paint had disappeared. Because of the small size of this piece, the CPC was simply sprayed from aerosol cans, wiping the excess film with a cloth. RMC has been involved in atmospheric corrosivity measurements for a decade in many areas, including Kingston, Halifax and Cape Canaveral.