Question
I am refinishing a solid Mahogany entry door and side panels. After removing the old poly and stain I have sanded it thoroughly and the different tones of Mahogany have appeared. The homeowner and I think it looks beautiful and we have decided to ditch our stain and poly plan and go with a clear. We understand the color will be uneven. The door is well protected from water but the lower half of it gets late morning-evening sun. I wash her house once a year so yearly upkeep is definitely an option and she would be willing to wash in-between also.
I am confused and have read all kinds of things to use such as Sikkens Door and Window, marine grade poly, boiled linseed oil, tung oil, etc. What can we use that will best protect the color of the wood, not necessarily last the longest or have the least upkeep, but keep the color true without repeated full on refinishing?
Forum Responses
(Finishing Forum)
From contributor Y:
If you are concerned about sunlight, weather, and durability the best thing to use is a UV Automotive Acrylic. We use this on all of our high end exterior products. It is not as durable on wood as poly for long term but will hold to about 75% of a poly finish life span. You will receive a superior sun bleach and fade resistant coating. Just don't forget to seal the top and bottom edge of the door with three times as many coats as the rest. The door can be waxed as needed to heighten the lust and extend the life of the finish with any automobile hand wax.
I am also about to begin (fabricating) three mahogany exterior doors, sidelights and transoms and am also in a quandary as to which finish to use. I've built hundreds of exterior doors in my shop, but this will be a first that we will be applying the finish - all previous work was supplied unfinished.
My situation is slightly different as two doors are shaded under porches, and the third door is on a north wall with just a little sun early in the mornings. I had just about settled on using the Sikkens, but am now interested in your application of automotive finish. I’m just a bit leery as wood is a whole different animal than metal when it comes to movement, expansion/contraction, and moisture content.
I use a phenolic resin-tung oil varnish and get as good as, or better results than Cetol. Boats take a lot more sun and weather than front doors, so that's what I would use, but I'd like to hear from Contributor Y regarding what works well for this application. I thought automotive finishes were a lot less flexible than wood finishes. Is there any problem with cracking and flaking due to the movement of the wood?
Contributor M - I had about settled on Sikkens Cetol Door and Window clear satin. I do not like the plastic look so much but Sikkens expands and contracts very well (Cetol 1 and 23 plus do not), is very easy to touch up, and easy to apply. However, being it is only clear I am very wary about how much U.V. protection it will provide, even with several coats.
Contributor R - would you mind also elaborating on the phenolic resin-tung oil varnish process? I'm not certain what it is or how it works, what sheen it will be, what the maintenance is, and how long with proper maintenance would you expect it to keep the color true before needed total refinishing?
I cannot stress enough that my concern here is protecting the wood and especially the color. I'm looking for something that will do this for years to come with proper maintenance, even if the maintenance is frequent, without have to take it all off and completely refinish it.
I sand between coats with 320-400 W&D. The first coat 50/50, second 70/30, the rest about 90/10, sometimes 100%. It is tough to spray; not so much application, but overspray makes everything incredibly sticky, but it can be done. The biggest drawback is dry time (I sometimes add some extra drier). I've found the single most critical factor in application is the quality of the brush. Badger is the lowest quality brush I use for varnish. I can't think of anything else at the moment.
Regarding maintenance, most boat owners do their brightwork every year or two. I'm thinking you might get two, three, or maybe more on your door. If you don't let it go too long and don't let the finish fail down to wood, you can just sand to clean and re-coat with a couple coats at70/30.
If it fails, then you will need to sand to bare wood and recoat three-five times. The trick is to not let the varnish coats fail. I get two-three years pretty consistently on yachts, work boats not so much. Two part LP is better for them. Something else I do on older wood (sometimes even new) is apply a 2-part CPES sealer coat before varnish (it’s easy, and also makes refinishing easier).
You could try MLC's Euro X, but you need to follow the products instructions for mixing very carefully. It's a 2K exterior poly that is almost bulletproof. Not sure about longevity and re-coating in the field.
Although the use was a more than an unusual request as I am sure you are aware, and the application had some strange effects to me as a finisher, the end product was truly beautiful. The coats required a slow thin build up, and the first two produce a gritty crystal like surface to sand. The overspray from our turbine sprayer produced a silly string effect as it dries as fast as it passes the applied surface. The finish produces a luster between what you would consider gloss and semi-gloss. I have never had a complaint from a customer and I do use this application on all exterior doors.
I am located in PA and in 2009 we finished a large scale interior project just outside Park City, Utah. We were asked by the homeowner to apply a decorative finish to their solid cherry exterior doors. We applied Permalac Automotive Acrylic Lacquer. As you are aware, the weather conditions in the mountains of Utah can go from desert conditions to subzero with extensive high altitude sun exposure. I have never had a complaint.
I can't tell you that it is the norm if that is what you ask. I can tell you I have had great success with these type of finishes for exterior applications over the years. I have been applying decorative finishes for 30 years and can honestly say that there have been many occasions that I have looked outside the proverbial box for better solutions.
Permelac was available regionally at our location. We ran a test finish on site on a piece of the cherry trimwork. We placed it in the midday sun along with a piece of the "UV Coated" Brazilian cherry floor from the flooring installer. We covered half of each. The property sites on Mount Ogden at 7,000 feet so the sun is quite intense. The following day the flooring had changed about ten shades from exposure while the trim piece remained consistent.
I am only here to pass on my experience. Do your research and always test for yourself. As for us, it only seemed a small leap of faith that an automotive acrylic would sustain the elements. To my experience, it has. When the circumstances were prevalent we have had good success without the sub material looking like plastic.
