Replies

1. 
   saschafer | Jun 01, 2009 07:02pm | #1

   Don't use ordinary linseed oil on an exterior project. Use only a product specifically intended for outdoor use, as it will contain mildewcides, which are not present in non-exterior finishes. This is especially important in the Deep South. I also wouldn't worry about trying to sand the surface too smoothly; having a little bit of "tooth" actually helps the finish hang onto the wood.

   I'm assuming this is genuine mahogany (Swietenia), not one of the many woods that is marketed as mahogany but don't have nearly the same durability. Genuine mahogany is a good outdoor wood all on its own. Over time, if you leave it alone, it will turn a silvery gray color. This is the low-maintanance option; as long as it has a chance to dry out between storms, it will last a long time.

   If you want to maintain the color, you will need a finish. The medium-maintenance option is to use a high-quality deck oil; Penetrol is one brand that gets good reviews. Although you obviously want the wood grain to show, the more heavily pigmented the finish, the longer it will last. You will need to reapply it at least once a year. You will need to strip and refinish maybe every five to ten years, depending on how well you take care of the finish in the interim.

   The high-maintenance option is a varnish finish. Fine Woodworking recently did a review, and Epifanes, a high-quality (and expensive!) marine-grade varnish, outperformed the rest. You will need to refinish every year, and will occasionally need to strip, sand and refinish.

   -Steve

    

1. 
   lauriek1175 | Jun 01, 2009 09:11pm | #3

   Thanks for the help.  I saw the article to which you refer and didn't know if it was worthwhile.  I think I will go back and read it.  I hope the new door is genuine mahogany.  I special ordered it from a builder supply not a big box store. It probably would be a good idea for me to double check with them.  Again thanks for the advice as I learn all about this stuff.  Laurie K

2. 
   SteveSchoene | Jun 01, 2009 07:25pm | #2

   Until you find a way to keep the afternoon sun off the door you will have a challenge to maintain a natural wood color.  Build a porch, add an awning, or plant trees.   

   Oil finishes without pigment will not last a full year.  Count on some light sanding and renewal every few months.  The more pigment, the longer the maintenance interval, but the less natural the look.  And, Steve Schafer's advise about using a quality exterior finish is important.  Mildew seems to thrive on linseed oil--the part of the door that gets the sun might not mildew, but the mildew would be highly likely on the shaded portion. 

   The most durable clear finish is the high gloss film finish provided by a quality marine spar varnish.  This is not the same thing that you might find at a local paint store or big box building supply company.  Epifanes was the top choice in the recent FWW article.  The directions call for 7 coats, and mean it.  Then an annual scuff sanding and an additional refresher coat.  Periodically, however, you will still have to strip off all the varnish and start over again. 

1. 
   WoodLess | Jun 04, 2009 05:39pm | #9

   Is the purpose of stripping off the finish every few years to avoid to much build up over time? ThanksChuck

1. 
   SteveSchoene | Jun 04, 2009 10:52pm | #10

   No, you will know it is time to do it because you will begin to see lighter yellow patches that indicates the varnish is no longer adhering at that point.  It happens even with the varnish film entirely entact because UV light ultimately attacks the lignum on the surface of the wood itself.  The UV absorbers put in the varnish for that purpose can only handle so much light before they are "used up".  That's a major reason why clear finishes last such a shorter time than opaque finishes which don't let light penetrate to the wood.  Tou can keep from getting excessive build up when you sand before applying the annual refresher coat. 

   Light colored paint works best because it reflects more light preventing the door from getting so hot. 

3. 
   mr_kramer | Jun 02, 2009 06:27pm | #4

   I would suggest that you give in a little. If you like the natural color of your wood, then just coat it with two coats of marine grade "spar varnish". If you want a lttlte darker color, that's fine. But remember that the darker the finish, the bigger contrast you will see when it starts to weather, especially in that sun. The sun will tend to bleach it out and the darker the finish the bigger the contrast. And yes. If you can afford to do so, a nice awning or overhang will also help to keep the driving rain off of it. But for maximum protection, "spar varnish" is the answer with whatever finish you decide on. Oh, and buy the good stuff from from a real paint store and not a home improvement warehouse. Even though they say that they carry it. It's not the same.

1. 
   SteveSchoene | Jun 02, 2009 06:55pm | #5

   Marine spar varnish isn't sold in paint stores either, except in a few yacht oriented towns the only place to fine real marine spar varnish is at a boating supply store.  Brands that consistently rate well are Interlux Schooner, Pettit Captain's, and particularly Epifanes, Clear Gloss.  And, the directions on all of these call for many more than 2 coats--more like 5-7 coats.  It is the thickness of the paint film that provides protection from UV.

4. 
   hammer1 | Jun 03, 2009 11:25am | #6

   You are looking for a finish that isn't a film forming coating. There are quite a few choices that will give an "in the wood" appearance, are fairly easy to apply and maintain. They have UV inhibitors and resistance to mildew.

   Most of these links will lead to recommended prep and application procedures. With doors, you need to pay special attention to the top and bottom edges. Some, like Defy can also be used on the interior. I've had good luck with it in the last couple of years. Most of these are fairly new products. They have been designed to replace high maintenance products like spar varnishes and also offer more environmentally friendly formulations.

   http://www.loghomesupply.com/men-wood-natural_26_d.htm

   http://www.messmers.com/prod_uh.html

   http://www.woodnewengland.com/cscart/DefHW.htm

   http://www.opwdecks.com/wolman-eht-hardwoods-1-gallon.htm

   Beat it to fit / Paint it to match

5. 
   JohnWW | Jun 03, 2009 07:25pm | #7

   Laurie,

   No matter what the wood is, genuine mahogany or otherwise, you will need to apply a top of the line outdoor finish to achieve the look and the durability you need, anything less will eventually disappoint you. I would follow the advice of the FWW article, using Epiphanes or a similar high quality true marine varnish, the epoxy undercoat probably isn't worth the effort.

   Use a gloss varnish, they hold up better, and use a fine steel wool after the last coat has dried for a few weeks to tone down the gloss. Apply the finish on both sides of the door to minimize stresses that could warp or crack the door because of unequal wood movement. Fit the door in the frame and install the latch, then remove the door to do the finishing, the edges, especially the top and bottom, will need to be finished also.

   As suggested already, shading the door from the sun, which is much more damaging than rain, will add years to the life of the finish.

   John White
   Shop Manager for FWW Magazine, 1998-2007

6. 
   oldusty | Jun 04, 2009 05:29pm | #8

     You might want to look into a " post catalyzed " finish.

           Find a paint store , ask