Finishes - Paint, Powder and Chemical Oxidation

Architectural metals require the most durable coatings manufactured by man. In today’s market this can encompass liquid sealants, heat fused powders, and/or chemical oxidizers. At times even a combination of these may be contained within one finished assembly. One thing is certain- all castings must be cleaned to bare metal prior to the application of any coating.

Zinc Thermal Spray is a direct method of galvanizing metal. In this process a zinc wire is fed through a heat gun where the material is melted and sprayed onto the surface. The resulting coating permanently seals the piece preventing oxidation. Zinc coated cast iron readily accepts primer and finish paint.

Robinson Iron recommends the specification of Tnemec® brand primers and finish paints as liquid sealants for cast iron, and steel as well as for cast and extruded aluminum. A pre-prime of Tneme-Zinc Series 90-97 is a zinc rich aromatic urethane. A primer of Tneme-fascure Series 161 is a polyamide epoxy.

A finish of Tnemec Endura-Shield Series 73 is aliphatic acrylic polyurethane.

The three are used together to coat all Robinson cast iron fountains. Special metallic effects may be obtained with Tnemec Enduralume, a flouropolymer urethane. More information about all of these high performance coatings may be found on Tnemec’s website www.tnemec.com. Their color labs in Kansas City are able to match any color so long as a number or swatch of the color is provided to them.

Powder Coating is an alternative to liquid coatings. In this process a fine powder of epoxy, hybrid, aromatic-urethane, aliphatic urethane, TGIC polyester or polyester wrinkle is applied to the surface and bonded in a heat curing process. The fused coating that results is an even durable finish. Powders come in many colors and effects. It should be noted that the material is unforgiving of touch-up and may present problems when refinished on site. Robinson Iron recommends the specification of DU PONT® powder coatings.

Chemicals may be combined to form acids which oxidize the surface of the metals to which they are applied. The rapid weathering produced can be subtle or dramatic. Heat may be applied as the chemical cocktail goes onto the surface giving the resulting patina a wider range of colors and effects. Chemicals used in this process are purchased from laboratory specialty suppliers

Anodized Aluminum is made with such a chemical treatment. Components are dipped into tanks of chemical to give their surface a broad range of color. An anodized aluminum surface is fairly stable and requires no additional coating.

Epoxy Paints come in a Part “A” and a Part “B” which when mixed together and sprayed “cure” into a hardened, durable surface coating.

The contrasting color of the Terra Cotta Primer enables the painter to see any “Holidays”.

Zinc Thermal Spray shoots a coating of hot zinc onto the surface of bare metal to galvanize the material against corrosion. A primer is applied afterwards.

Robinson’s Antique Verde Gris Finish starts with a gloss black and is antiqued with a wash of Industrial Enamel.

Powder Coating on this waterjet cut “Star” has a very even finish which can be difficult to touch-up in the field.

Specialty metallic paints like Tnemec Enduralume shown on these tubing samples produce a very hard surface coating.