Hello all
This is my first appearence here. I’ve done a search on this topic, and read lots of good discussions, but still have a couple of questions.
I’ve trimmed out an entire house in Phillipine Mahogany, to include window jams, window/door casings, base, cabinets face frames and drawer fronts…about 1,200 sq ft. Was planning on African, but got a deal on the Philipine I simply couldn’t refuse. The wood is a clear, straight, premium grade and has been easy to mill and shape…although its a bit softer than I would have otherwise wanted. But anyway, its all in place. Now, to finishing.
The wood looks so nice as is, I don’t plan on staining, but I’d rather have a durable finish that will stand up well to sunlite and wear. It has a fairly bright red hue that fits the house’s ambiance well, and I’d like to keep it that way….or close to it.
I was considering simply using an oil based poly, using UV resistant on all window jams. To ensure penetration, my plan is to cut my first coat about 50% with mineral spirits and then apply the next two coats out of the can, steel wooling with 4-0 between coats.
Is this too simplistic? Am I missing something I should be doing? It seems that most previous posts focus on filling the wood pores first. Is this step really necessary?
I appreciate all constructive views and advise.
BruceM
Replies
Number one the UV protection starts to breakdown rather quickly,usually about one year.
Number two polyurethane varnish is a poor choice for clarity and non yellowing. A better choice would be an alkd varnish made with soya oil(starts clearer and stays clearer than most) Pratt&Lambert #38 and Sherwin Williams Fast Dry are a couple.All varnishes made today should be thinned before using. I usually thin the first coat about 50/50, but then i thin all the coats a little (just personal preference.
Regards
Jerry
If you thin with mineral oil it will take forever to dry.
I usually use naptha or even lacquer thinner in order to cut down on dust problems.
BTW, I wouldn't use poly either.
I should have added mineral spirits, didn't mean to infer mineral oil,sorry if I did.Regards
Jerry
Hi Jerry,
I kinda figured that is what you meant, however I'd still use naptha.
nic
I'd look at a marine varnish (Epifanes, Interlux etc.) or Five Year Clear (http://www.fiveyearclear.com). UV resistance comes from multiple coatings of varnish NOT from a single coat. However, since common window glass filters approximately 80% of the UV - it's not exactly like having the coating outdoors. On wooden boats it's not uncommon to put 12-15 coats of varnish. Once this is applied, you can tell when the top coat starts to breakdown as it will turn a little dull and after that a bit milky. With wooden boats, that's when you sand lightly and apply another top coat. As long as you do that and don't let the first and second layers get UV damaged (when the varnish begins to crack and "alligator"), then finish is preserved.
Most boat restorers like to thin the first coat 50:50, and then put all other coats on either unthinned or with not more than 5-10% thinner. Use the varnish manufacturer's thinner specified for the varnish as that will work much better than naptha or mineral spirits. Some varnish manufacturers will have separate warm temperature and cold temperature thinners to preserve the varnish flow-out and smoothing.
The problem you will find with mahogany is that the grain will show through the surface as a stipple pattern until about coat 6-8 unless you use a grain filler - that's why boat restorers like to use straight varnish and not thinned varnish. It builds to a totally smooth finish much faster.
If you don't want to go to all that trouble, I'd consider a rubbed tung oil finish with at least 3 coats. That way the grain can show without it taking on the stippled appearance you get from a varnish finish that hasn't been applied in multiple coatings or over a grain filler.
Unless I misread the posting he was asking about interior finishes,and unless the house is made of glass UV protection shouldn't be a major concern.RegardsJerry
Jerry -
Read the original post.
One of his concerns was UV resistance. That's NOT an issue I brought up, it is part of his original question.
I don't think that issue will really come into play in this case. If you read my post carefully, you'll see I'M the one who brought up the fact that window glass filters a great deal of the UV.
The remainder of the information on varnish UV resistance is just information on varnishes in general. UV resistance comes from multi-coat application, and not just from how it's formulated. That means that a good UV poly properly applied should work fine specifically because it's being used indoors with filtered light.
I'm also the one that suggested tung oil would probably work - and that's NOT known, when used alone, for a huge amount of UV resistance. Does that clarify MY understanding of his original question for you?
Thanks very much for the info.
I like the boat analogy, as that is one of the finish effects we're trying to get, as the interior of the house is a marine decor. But 6-8 coats?! Yikes! Should I not cut the poly (or varnish) at all to get the build-up faster?
Great thought on using laquer thinner rather than mineral or napfa...as even though we'll have cleaned, vacuumed and carefully dusted, its still a dusty environ, and the longer its wet, the longer the surface has the opportunity to collect dust.
I'm a veteran Tung Oil user, and like it a lot....but it doesn't hold up as well to hand prints and kick-marks.
And yes, I see your point about filling as the way to reduce the surface of the wood 'drinking' more of the finish.
Thanks for all the ideas.
BruceM
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