Problem Solving Forum
April 18 - April 24, 2011
What is the best way to prevent tropical hardwood deck lumber like ironwood from developing a gray patina in sunlight?
Allen Zielnik of AMETEK Corp on
April 28, 2011:
Ipe (a.k.a., Ironwood, Brazilian Walnut) is about ...read more Ipe (a.k.a., Ironwood, Brazilian Walnut) is about 8X denser than California Redwood and is one of the most durable and rot/decay-resistant tropical hardwoods. New, it has a dark brown walnut color. Like all wood, cellulose and lignin at the surface are very UV degradable and in sunlight will fade to a very nice silvery gray (it is left natural in many parts of the world) without problems. A non-film-forming penetrating oil or water-based finish with penetrating oils with UV absorbers (UVAs) is mandatory to prevent discoloration; however, sometimes UV-blocking pigments (transparent nano or colored) may be added. This becomes an ongoing process and must be repeated, maybe yearly or more often, depending on sun and weather exposure.
Joseph Schinner of Akzo Nobel Coatings Inc. on
April 21, 2011:
I'm not a wood expert but should be able to get yo ...read more I'm not a wood expert but should be able to get you started: 1) My wood consultants always emphasize putting on the clear coat before any weathering can take place; prepainting before construction is frequently the easiest. 2) Even the above only somewhat delays discoloration unless UV absorbers and HALS (Hindered Amine Light Stabilizers) are part of the clear formula. Note: the clear outer layer of the automotive paint system is where these are located.