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Weather and corrosion resistance for exterior projects.
First, before you read on, we can reduce massively the effects of corrosion but nobody can eliminate it. We do not claim that at all. What we do at SES is protect the surfaces of metals with coatings and materials . Damage those surfaces and expose the bare metal and corrosion will happen. Use over the counter paints and primers and soon the dreaded red stains will appear, in fact you can make matters much worse with items such as cast railings and other exterior fittings. The successful conservation of cast-iron architectural elements and objects is dependent upon an accurate diagnosis of their condition and the problems affecting them, as well as the selection of appropriate repair, cleaning, and painting procedures. Frequently, it is necessary to undertake major repairs to individual elements and assemblies; in some cases badly damaged or missing components must be replicated. The long-term preservation of architectural cast iron is dependent upon both the undertaking of timely, suitable repairs and the commitment to a regular schedule of maintenance and surface protection.	Delaminating Cast Iron
We apply surface coatings that seal the metal from the elements. We apply anodes and coatings that actively react when exposed to weathering so as to corrode before the underlying material (why aircraft do no rust or corrode) as well as protectiong against further attack. We use long lasting hot oil waxes internally to resist the formation of condensation on the insides of iron statues, these protect the surfaces, prevent absorption into the cast metal (cast iron is porous and actively absorbs moisture and acids) and always use the highest rated zinc and phosphate based primers, these we apply in substantial thickness for very long acting protection and with professional equipment. A sealing coating of epoxie based coatings can be used but these, as they are sensitive to UV light, then themselves need a top coating to complete the process.	A stabilised surface on a lead casting
Corrosion is a complicated issue, it depends on the basic materials, the of combinations of materials used to construct an item, the properties of fluids and partials that contacts the item, the temperatures, the surrounding environment and minimizing any galvanic action between items.
Acid rain is a major modern factor, it was not encountered as much when the older items were made years ago and greatly effects all metals and stones. It attacks lead figures rapidly and discolors paints
We offer a "SERVICE" once a year that will maintain the object and protect the surfaces, inside and out.	Expansion damage cracking stone base due o failed caulking
Read on to look deeper into Cast Iron as a material and how to prevent problems. Read on some more about the technical issues
Graphitisation of cast iron occurs in the presence of acid rain precipitation, we have found this an increasing problem for item situated in cities due mainly to pollution rates being higher . As the iron corrodes, the porous graphite (soft carbon) corrosion residue is impregnated with insoluble corrosion products. As a result, the cast-iron element retains its appearance and shape but is weaker structurally. Graphitisation occurs where cast iron is left unpainted for long periods or where caulked joints have failed and acidic rainwater has corroded pieces from the backside. This greatly effects those properties with railings and cast iron balconies. Severe attack requires total replacement. Testing and identification of graphitisation is accomplished by scraping through the surface with a knife to reveal the crumbling of the iron beneath.
Galvanic corrosion is less of a problem as mixed metal structure are not often used in architecture. Cast iron however will be badly attacked and corroded when it is adjacent to more noble metals such as lead or copper.
The minimum relative humidity necessary to promote rusting is 65%, but this figure can be lower in the presence of corrosive agents, such as sea water, salt air, acids, acid precipitation, soils, and sulfur compounds present in the atmosphere, which act as catalysts in the oxidation process.
Maintenance, a detailed explanation. A successful maintenance program is the key to the long-term preservation of architectural cast iron. Regular inspections are essential when using ANY item that the public have access to. Annual inspections, occurring ideally in the spring or Autumn, include the identification of major problems, such as missing elements and fractures, as well as minor items such as failed caulking at the base of railings and other items "inserted" into stone and masonry. Damaged paint, and surface dirt is checked for and repaired or cleaned. Records should be kept in the form of a permanent maintenance log which describes routine maintenance tasks and records the date a problem is first noted, when it was corrected, and the treatment method. Painting records are important for selecting compatible paints for touch-up and subsequent repainting. The location of the work and the type, manufacturer, and color of the paint should be noted in the log. The same information also should be assembled and recorded for caulking. Superficial dirt can be washed off well-painted and caulked cast iron with low-pressure water. Non-ionic detergents may be used for the removal of heavy or tenacious dirt or stains, after testing to determine that they have no adverse effects on the painted surfaces. Water and detergents or non-caustic degreasing agents can be used to clean off the residue however it is necessary to check that good drainage is present. Deposits from these these MUST be removed prior to finishing so as not to trap them in the metals surface and cause damage to coatings over time. Before repainting, oil deposits and grease must be removed so that new coatings will adhere properly directly to the metals surface. The primary purpose of the maintenance program is to control corrosion. As soon as rusting is noted, it should be carefully removed and the protective coating renewed in the affected area with similar products. Replacement of deteriorated caulking, and repair or replacement of failed flashing's are also important preventive maintenance measures.