I normally send most of my finishing out to a friend, but am close to finishing a piece for my nephew who will be doing his own finishing.
The wood is pretty dark genuine mahogany, that has some white chalky deposits in the pores. I have seen this before, but I don’t recall if there is a term for it, nor do I know if it requires some special treatment to eliminate it in the finishing stage.
Will it just disappear with the wetting out of the pore with finishing material, or does it need to be stained, and filled? I think the neph will probably just use an oil, or wipe on poly.
I would hate for him to wipe on a clear sealer, then have it pop back up, then have problems covering it with a stain.
Replies
Keith,
I too was concerned about that, the first time I made something from mahogany. It won't have any effect on the finish, in fact I have found that mahogany with white pores is usually a little bit more dense and of high quality.
Rob Millard
http://www.americanfederalperiod.com
Thanks Rob, I have to agree with you that it is more dense, and darker, and nicer to work. It has been a while since I have seen any as nice as this. It is getting harder to find any genuine around here for the past few years. I know that I should known about any finishing problems, but I got to questioning myself, and I know that my nephew and his wife are going to be questioning whether there will be problems, and I have to admit that finishing is not my strongest suite.You got a name for it?
I read a name for it somewhere, but I couldn't remember it, nor could I find the article.
Rob Millard
http://www.americanfederalperiod.com
Aloha Keith, Swietenia has the mineral deposits in the pores and it is truly wonderful to work and finish. Here is what is happening to the Honduras varieties. As they get logged off there is no replacement planting. Instead, they are being replaced with African oil palms by the same companies that have taken over all of the Indonesian and Malaysian forests-25 million acres to date and completely altering ecosystems. Hondo mahoganies are now CITES listed and selling for 10-14 dollars per board foot. Enjoy it while you can and only make beautiful things with it. mike
Edited 3/21/2008 4:36 am by mikegagne
There do exist Honduras mahogany plantations (see, for example, http://www.exotichardwood.com/). Unfortunately, there aren't yet enough of them.
-Steve
Palm oil plantations will guarantee there will never be enough mahogany. If you drive the coast highway in Costa Rica there are miles of African Palm Oil palms where there used to mahogany and native trees. There wont be mahogany in my working life from those few new plantations. mike
I've seen the oil palm plantations, in Ecuador as well as Costa Rica, stretching as far as you can see. I've even gotten an up-close-and-personal look at forest destruction for the sake of oil palms: In January 2001, my wife and I visited an area of northwestern Ecuador on a birding trip, where we saw numerous species new to us. We visited the same site two weeks later to find a bulldozer clearing the forest, and watched it knock down a tree that during our prior visit had given us three new species. A few days later, we wrote a check for $1000 to donate 20 hectares of primary forest to a preserve, something that we now do after each of our visits to the tropics.
There are a few rays of hope in the sometimes overwhelming sea of bleakness: While there is still a very long ways to go, we were able to see that attitudes towards the environment in Ecuador had improved dramatically between our 2001 and 2006 visits. Tree farms are increasing both in number and in size (especially in Costa Rica and Panamá). And specifically in regards to oil palms, it appears that they require a climate that includes a well-defined dry season, which means that there are significant areas in the tropics where it is not economical to grow them.
-Steve
Hi Keith,
I think those are mineral deposits in the pores of the mahogany. Perhaps someone more knowledgeable than I can comment but I was told to wipe the wood with muriatic (?) acid - I think - just before finishing. Any sanding will expose fresh wood with newly unroofed pores and their little white mineral contents. Such is my understanding.
-Vivian
Vivian,
Muriatic Acid is a consumer name for hydrochloric acid which has a ph of 1.0< I don't think you want that on any wood you are going to finish. If the mineral deposits in the mahogany are a carbonate compound (limestone)the HCL will indeed react with the mineral and eliminate it in the pores, but then you will need to neutralize the acid with a baking soda solution. I am not sure you want to attack any wood with HCL, let alone Honduras Mahogany. If the mineral is silica, acids will have no effect. Carbonates should accept stain easily, silicates will not accept any stains or dyes just pigments to cover them up. I was a Chemistry Teacher in my working life. Now I am a fisherman and a woodworker, love both stages.
Terry
Hydrochloric acid is a non-oxidizing acid (as opposed to sulfuric or nitric acids, for example), and plant-based materials typically tolerate it well. That said, I agree that I wouldn't want to use it without making sure that I can neutralize it afterwards.
-Steve
Steve,
My concern was not oxidation, although a cool demonstration is having your students watch sulfuric acid turn wood into a pile of black gelatinous ooz, my concern was the finish. Catalysts are acid based and I am not sure what HCL residue would do to whatever finish is being used. Sherwin-Williams does not even recommend aluminum cups on precat lacquer because of the acid catalyst. I still use one, but I don't let it sit in the gun too long.
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