Finishes for Exterior Honduras Mahogany
Lots of deck railings, a staircase and some other exterior projects to build with Honduras mahogany. Most faces North, a bit East, none South and much of East and West mainly in the shadow of the house.
Some MUST be painted. Alkyd, latex or combination? The part that must be painted is replacement after rather rapid and unexpected failure. It’s about 20′ above grade on balcony with semi-open roof tucked into the NE corner of the footprint of a rectangular home. Lots of natural shading in a warm, humid environment (mid-Mississippi valley). Previous railings were fine for a few years until a 6+” summer rain followed by the most humid weather I’ve ever experienced–the sky literally dripped each evening before dusk for over a week. Railings were primed with alkyd with two top coats of latex. The PRIMER mildewed UNDERNEATH the top coats and then rot sat in.
Finish of the rest is still open to suggestion. Painted, clear finish or both could be used. My old woodworking books say that mahogany should be painted for exterior use, not because it will rot, but because of unspecified “appearance” problems. Is it safe to assume the appearance problems are ugly grey color and cracking? One book did however say that mahogany shop fronts “naturally” polished via burnishing were suitable for many years of beautiful appearance in cool, foggy London. I have an idea how to do such, but any suggestion regarding details and if it’s practical with regards to both time and a wildly variable climate?
Is there any PROVEN clear finish that can be used? I guess I could deal with a 5-year maintenance (read re-coat with proper prep) interval for such, but considering I’ve had no problem with 10-15 years for a good paint job around here, I’d NEVER consider annual or even semi-annual re-coating.
Replies
I don't know of any clear exterior finishes that you'll get five years out of. Talk to a boatbuilder, those folks pretty much recoat every year.
I have heard of oil based exterior paints mildewing but have no personal experience with it.
Maybe you might have good luck with a solid body stain, such as cabot's, or maybe even ben moore's. I believe those can be applied directly to most species of wood unprimed.
Dustin
You've confirmed what I already thought, have experienced (with traditional spar varnish) and even advised with regards to exterior clear finishes. Some have said there are new "miracle" products, but I don't really believe. Call it the "Show Me" state thing...
If an opaque finish I'll just go with paint that I know will last.
Don't want to open a "oil vs. latex" thing, but would like to hear from others who have used and painted mahogany outdoors.
Try Sikkens brand finishes. Did a 1000+ sq ft deck in WV a number of years ago, originally was to be a Trex deck with Ceder trim, Trex was back ordered 3 times and the owners decided on all ceder. The deck needs to be redone every other year, but the rails and the pickets and vertical boards last form a number of years. It calls for all surfaces to be sanded prior to applying the first coat and then there was some crazy wait time between coats 2-3, but if done right the product lasts
Thanks! I'm checking out the Sikkens finishes now.
Believe me--sanding before is a GIVEN. These are highly refined railings on one of the best examples of Colonial Revival in town. The open-string, solid riser staircase will have neither exposed end grain nor exposed fasteners replacing an experimental version of such in treated (CCA pine) wood. It's still perfectly serviceable, but even with significant weathering before machining, expansion/contraction have opened rather large gaps.