![]() It thus significantly increases the durability and, hence the service life of copper roofing and flashing. The sulphate patina, on the other hand, is highly resistant to all forms of atmospheric corrosion, once it has formed completely. Neither the oxide nor sulphide films are particularly corrosion resistant. The progressive oxide, sulphide and sulphate films which develop on copper exposed to the atmosphere are quite thin – 0.05 to 0.08 millimetres – and highly adherent, but with relatively low abrasion resistance. The critical variable, in all instances, is the dwell time of moisture on the exposed surfaces. Similarly, exposed horizontal surfaces develop the patina more rapidly than sloping surfaces which, in turn patinate more rapidly than vertical surfaces. In arid environments, the basic sulphate patina may never form, due to the lack of sufficient moisture. In rural atmospheres, where the quantity of air-born sulphur dioxide is relatively low, patina formation may not reach a dominant stage for 10 to 14 years. In industrial and seacoast atmospheres, the natural patina generally forms in from five to seven years. This temporary colour phase is caused by the thin oil film, which is quickly washed off by rain, allowing the natural weathering of copper to proceed. This film may give rise to dark purple or black surface colourations soon after installation and exposure. During continued exposure, these interference colours fade and are replaced by relatively uniform russet brown shades, referred to as statuary or oxidized finishes.ĭue to varying fabricating procedures, some mills may coat coiled or flat sheet stock with a thin coat of anti-stain oil film. ![]() The Water Based Milk Paints are not compatible with Linseed oils or Danish oils.The natural weathering of copper to the characteristic blue-green or gray-green patina is a direct consequence of the mild corrosive attack of airborne sulphur compounds.Īs natural weathering proceeds, the metal exposed to the atmosphere changes in hue from the natural salmon pink colour through a series of russet brown shades to light and dark chocolate browns and finally to the ultimate blue-green or gray-green patina.ĭuring the initial weeks of exposure, particularly in a humid atmosphere or in areas of frequent rainfall, radical colour changes often take place with iridescent pinks, oranges and reds interspersed with brassy yellows, blues, greens and purples. Applied with a brush, roll, pad, or spray.A ll you have to do is prep your piece, stir the can and get started! General Finishes Patina Green Water Based Milk Paint Quart Specifications: It is a premium paint, carefully engineered for durability, ease of application and exterior use. You can mix it, lighten it, distress it, glaze it, layer different colors or antique it - perfect for up-cycling or repurposing furniture. ![]() It is adaptable and UV resistant, and can be applied with a brush, roller or sprayer possessing excellent flow and leveling properties. Milk Paint is a modern version of old world paint with a strong mineral base. It is premixed and does not contain any casein based ingredients yet it is extremely durable and that's why it is so popular for painting cabinets and furniture. General Finishes Milk Paint is a high quality low VOC self sealing interior/exterior mineral-based paint named for it's low luster sheen.
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