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I’m about to finish a bookcase made from Red Oak with Cocobola inlays. I want to do two things: 1) have a natural finish which doesn’t transfer to books or paper sitting on the shelves; 2)preserve the colors in the Cocobola wood and keep it from darkening severely from exposure to light.
For a natural finish (#1)I was considering using Tung oil but read that oil finishes shouldn’t be used on a bookcase because paper will pick up the oil on a hot day. Is there another natural finish I should consider? How about natural Danish oil?
I’m at a loss for how to preserve the colors in Cocobola (#2) while still having a natural finish. The only finish with UV protection I have seen is Polyurethane. Would it be possible for me to mix Polyurethane with Tung oil or Danish oil? Any other suggestions?
Any help is greatly appreciated.
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A drying oil like tung or boiled linseed won't bleed on your books once cured. Yes, you can mix oil and poly. Add some thinner and you have Danish Oil (e.g.Watco). Danish Oil is a nice looking finish for oak, IMHO. I've had a set of books sitting on top of a old roll top desk finished with Danish oil, and after 15 years they have zero oil on them.
You could get a little more protection by thinning poly half and half with a thinner and wiping on several coats. This is a very easy application method, and you can leave the finish quite thin so it does not have a lot of build up. Again, IMHO, a thick finish does not look good on oak, others will disagree. You can find more on making and using wiping varnish at http://www.gis.net/~dheaton/woodworking/woodworking.shtml. Look for the "finishing notes" at the bottom of the page.
You might slow the change in the cocobolo, but nothing will stop it. Sorry.
Sounds like a very nice book shelf!
- Rod Cole
*First, what do you mean by a "natural" finish? I would consider pure tung oil, linseed oil and shellac as natural. Most other finishes have manmade resins, driers etc. Even the additive that is used for UV protection is manmade. As far as UV protection is concerned it only works when it it built to a rather thick film. On boats we use 6-8 coats of varnish with UV inhibitors and these lose their effectiveness within a year or so. Generally, UV inhibitors are not used on indoor projects. Personally, I would consider a "Danish Oil" type finish using a homemade mixture of equal parts, boiled linseed oil, mineral spirits, and varnish. Or buy Watco Danish Oil. Finally--or maybe firstly--I recommend you purchase "Great Wood Finishes" by Jeff Jewitt and published by Taunton Press. It will give you all the info you need to produce an excellent finish for your project.
*Thanks for your responses.By natural finish, I mean one which leaves the wood looking natural (without a plastic-like build-up).As for UV protection, are you saying there is nothing I can do to keep most of the original color of the Cocobola wood?
*Has anyone used Polymerized Tung oil (available from Lee valley & Veritas)? How does it compare with pure Tung oil and why use one over the other?
*First, all clear lacquer and varnish finishes contain "plastic" as the resins that give the finish their body are "plastic". What makes for the "plastic" look on some polyurethane is the effect of a multicoat build up which lead to a bluish cast the can look 'plastic".The only way to minimize sun affecting the wood is to keep it out of a bright room. All wood changes color even in a closet. Oxygen will cause oxidation darkening in wood. Certain woods react to a greater degree than others.Polymerized tung oil is an oil that has been heated with the intent to make it dry (polymerize) more rapidly. Pure tung oil is very slow to dry. Once dry, there is no difference between polymerized tung oil and regular pure tung oil. Either is relatively expensive and requires frequent re-coating. It is also a very poor finish from a durablility point of view. It offers not water or water vapor protection and like most pure oil finishes, it gets dirty quickly.
*I was told tung oil gives you a very hard and durable finish, that's what they use in bowling alleys. Did I get the wrong info? So polymerized tung oil is to tung oil as boiled linseed oil is to linseed oil?
*>>I was told tung oil gives you a very hard and durable finish, that's what they use in bowling alleysWhoever told you that didn't know what they were talking about. Oil, any oil, is a very soft, non-durable finish. It offers next to no protection at all. Bowling alleys are varnished generally. They are oiled in use to control the "grab" but not as a finish.To some extent, polymerizing tung oil is similar to the adding of metallic driers (boiled linseed oil is not longer actually boiled) to linseed oil. The intent of both is to speed curing.
*I am making a wine rack out of Cocobolo. I have put one coat of Tung Oil on and after 36hrs it is still tacky in places. Do I need to wait until it is completely dry before I rub it with 0000 Steel wooland apply another coat?In reading through some of the forum comments I have also become concerned about the fact that the Cocobolo will darken. How dark are we talking here and how long will this process take?Finally, what is the safe and "environmentally friendly" way to dispose of the tung oil soaked rags once you have used them; can they be washed and re-used?
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