Refinishing Mahogany Piano - Deft/Tung vs Tung Only - Woodworking Talk - Woodworkers Forum
 
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post #1 of 12 Old 09-15-2008, 06:28 PM Thread Starter
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Refinishing Mahogany Piano - Deft/Tung vs Tung Only

[I just realized that I posted this in the general forum, but probably should have posted it here. Apologies for any inconvenience.]

Hello. I'm new to the forum and appreciate any advice you might have for my project. I'm refinishing a 100-year-old grand piano that has a mahogany veneer. Based on my research, my inexperience with lacquers and my workspace (which is a relatively dusty garage) I planned to finish the piano using Formby's Tung Oil Finish. I understand that the tung oil finish is forgiving (good for beginners) and that if I am patient and apply enough coats of it then I can achieve a deep satin finish that brings out the natural wood grain.

An acquaintance of mine that has refinished a few pianos suggested that instead of using just the tung oil finish, I should apply one or two coats of Deft Clear Wood Finish Brushing Lacquer, sanded with very fine sandpaper between coats, and then apply the Formby's Tung Oil Finish until I reach the luster I like.

He suggested that a Deft/Tung Oil process would be an improvement by:

(1) increasing the consistency of the tung oil finish. I'm confused by this, because I thought lacquer would make penetration of the tung oil finish impossible and the tung oil finish would just sit on top of the lacquer. Is that right? Does it matter? Either way, after speaking with him I'm concerned that using the Formby's alone could produce splotchy results,

(2) increasing protection of the wood and reducing its sensitivity to humidity/temperature changes. Ok, that makes sense since lacquer is hard,

(3) filling the pores of the wood for a more mirror-like finish. That makes sense too and is probably desirable, although I fear that dust getting into the finish and any uneven application by me could ruin the look in the end, and

(4) make the process a lot faster, since I could apply the Deft fairly quickly and reduce the number of coats of tung oil finish needed.


So, what do you think?

I am willing to try the Deft/Tung Oil process if it is really better. I would probably apply the Deft Clear Wood Finish Brushing Lacquer with an air-powered spray gun that I've used to paint furniture. I think I would probably do a better job with the spray gun than with a brush, although I'm still worried about dust.

If, on the other hand, using the lacquer will just complicate things then I'm happy to hand rub with only tung oil until the cows come home.

Any help you can provide is greatly appreciated. Many thanks for your time.

Leo
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post #2 of 12 Old 09-15-2008, 10:25 PM
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i've worked a little with mahogany but not with mahogany veneer and i'm not about to try to give you advice on finishing a 100 year old piano but, just in case you didn't know, the formby's tung oil finish isn't tung oil at all. it's more of a wiping varnish. it has about as much tung oil in it as a can of coke. as for putting it over the top of lacquer, i suspect the same as you do and that it would sit on top of it.
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post #3 of 12 Old 09-15-2008, 10:39 PM
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I posted on the other thread, so I moved it here.

What you apply will depend on the finish you're looking for. Lacquer in conjunction with an oil is not a recommended method. If you are looking for a high gloss piano finish, using Tung Oil you'll think the cows got lost before they get even near home. If you are looking for a natural wood look and feel, the Tung Oil Finish, which is really a 3 part mix of basically a varnish, boiled linseed oil, and mineral spirits, will provide a natural look and feel with a shine. It can be wiped on and after each coat is dry sand with 320x. You can judge the look you're after with subsequent coats.

Applying an oil over lacquer will do nothing as a finish. If you are spraying lacquer in a garage that's dusty, you'll definitely have a finishing problem.

If you want a high gloss polished look, you should first use a paste wood filler. In using lacquer, there has to be a substantial build of coats. In between coats should be wet sanded with 400x to 600x wet-or-dry silicon carbide sandpaper and water. The final coats should be wet sanded up to 1800x to 2000x. It then can be polished out to a high gloss using a smooth pumice and then rottenstone. Or, ordinary automobile rubbing compounds can be used finishing with a ultra fine polish. Other compounds can be used in graduated smooth grits of rouges.

Each coat application should be cured before wet sanding.






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post #4 of 12 Old 09-16-2008, 11:57 AM
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Quote:
Originally Posted by cabinetman View Post
If you want a high gloss polished look, you should first use a paste wood filler. In using lacquer, there has to be a substantial build of coats. In between coats should be wet sanded with 400x to 600x wet-or-dry silicon carbide sandpaper and water. The final coats should be wet sanded up to 1800x to 2000x. It then can be polished out to a high gloss using a smooth pumice and then rottenstone. Or, ordinary automobile rubbing compounds can be used finishing with a ultra fine polish. Other compounds can be used in graduated smooth grits of rouges.

Each coat application should be cured before wet sanding.






Thanks Cabinetman,
Gotta do a sub woofer for a friend, wants it black lacquer. That was the tip I needed.
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post #5 of 12 Old 09-16-2008, 11:59 AM
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Since you say this piano is 100 years old you might want to have it appraised before you do anything to it. Formby's tung oil finish is a very thin wiping varnish made with soy bean oil and alkd resin. Your friend may mean well ,but his finishing advice is in error.

Regards

Jerry
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post #6 of 12 Old 09-16-2008, 01:46 PM Thread Starter
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Many thanks to all of you. I'll definitely be going with the Formby's alone. I did know that it isn't really tung oil from reviewing other posts. Doesn't matter to me so long as it's relatively easy to use and gives a nice natural finish. Really glad I didn't botch up with lacquer and have to strip the piano twice. On the appraisal, pianos are a little different than most other antique objects. It's the musical portion that counts more than the case. In my situation, the internals are fine, but not great, but that's enough for me at the moment. I'll dump a few thousand in it if the economy rises from the dead. The case, on the other hand, is in great shape and pretty, so the wife likes that. All that being said, I'll take care to do it right. If it goes well, I'll post some pics of the before and after. If it doesn't, then I'll google a beautifully finished piano and send you pics of that instead; just kidding.

All the best,
Leo
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post #7 of 12 Old 09-29-2008, 12:50 PM Thread Starter
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Wood filler, then Formby's, or better to stick with open grain?

After a couple weekends of stripping, I've almost got the piano body down to clean mahogany veneer. At this point it seems as if it will look fantastic finished. I had intended to use Formby's Tung Oil Finish on the open-grain. I thought that wood filler was only to be used as prep for lacquer finishes (as described by Tweegs). But then I read the following excerpt. Does this mean you can use wood filler and then use the Formby's? Am I right in guessing that this wood achieve a glossier, less grainy finish? Is it worth it? Many thanks again for all of your help.

Excerpt from http://www.wwch.org/Technique/Hutch/Perfection.htm:

"Next, the secrets of a spectacular finish.
If you want to fill the pores, now is the time. I use DAP wood filler. Yeah, that’s right, the cheap water base stuff from Home Depot. It works great and sands easily. Dilute it down with a little water to mayonnaise consistency and rub it on in circular motion with a small cotton pad covering an area of about 4"x 4" at a time with overlap. Don’t worry about how it looks for now, because it will look just awful. If you spend more than five minutes on a tabletop you are wasting your time. Let the filler dry, preferably overnight. You have now raised the grain on the stock and simultaneously filled the pores. Both of these are desirable. So far, so good. Sand using a random orbit sander with 80 grit to eliminate the last traces of machine marks, then progress to 120 grit on a finish sander. You will see the filler in the pores. This is the desired result. This filler takes a stain nicely. You can also dye the filler prior to application with a smidgeon of aniline dye. Striking results can be obtained with contrasting dye colors. You are now ready to stain or dye your piece. Dust is off.
Before opening the stain, mix it up thoroughly. Most stains contain a mixture of soluble dyes and insoluble pigments. The pigment tends to settle out, so keep them mixed during the application. To apply use a small pad of your old cast off tee shirt about 2"x 2". Dip the pad into the stain lightly and wipe it on thoroughly in circular motion, with final passes in the direction of the grain. Do no allow the stain to run. Less is more. This is a wipe on technique so you just rub it until it is uniform. Start at one end of the board and continue to the other. When you have completed a section, immediately go over it again with another coat starting at one edge and continuing to the other edge without stopping in the direction of the grain. You will notice that the figuring in the wood takes the stain at different rates with some areas absorbing more stain than others. This is due to the orientation of the wood fibers that contribute to wood figure and is a desirable result. Complete coverage of the entire piece using this technique. Let it dry overnight.
Now is the time to remove those glue traces and affect any last minute repairs. Then rub out the dried surface with 0000 steel wool in the direction of the grain only. When the wood offers little resistance to the rub out you know that you have completed it properly. You should now have a glassy smooth, satin surface. Dust off the piece and apply a second coat of stain by starting at one edge and continuing to the other without stopping. Allow drying overnight. Apply several coats of tung oil using the same wipe on technique. Each successive coat is easier to apply than the last. Change the pad if it begins to get a little gummy. You can apply several coats of tung oil the same day as it dries very quickly. Allow about two hours between coats. The more coats applied, the higher the gloss and durability. I use the high gloss Formby’s Tung Oil. When the project is finished, it should look like you can poke your finger into it. You have now achieved perfection. Apply a final coat of carnauba wax and buff out."
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post #8 of 12 Old 09-29-2008, 01:47 PM
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Mahogany is an open grain very porous wood. Using a grain filler will give a smoother finish. I prefer to use a solvent based filler like this.

The solvent based filler will not raise the grain like a water based filler, and may require less sanding. You must follow the application directions exactly, as if it's applied or wiped off incorrectly, you will have a very difficult time achieving a consistent look. Most fillers work in cross grain first then wiped with the grain. If they dry without wiping it's hard as heck to get it off.

After the filler step, apply thin applications of the oil and let each application dry. Heavy applications will stay wet too long and may be a gummy start to the next application. Dyes or tints that are compatible with a solvent filler can be used. It takes very little to tint the filler. You'll have to experiment with samples if you tint the filler.

If you just apply the finish without the filler, you will have to lightly sand with the grain with 320x and your final application will still have a wood look and feel. If you can try out the two methods on an area that won't show, it may give you a better idea of what you're looking for.






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post #9 of 12 Old 09-29-2008, 03:04 PM
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If you ask 10 people how to finish,

you will get 11 answers.
With that said, I will now throw my 2 Cents in.

Your garage is dusty. That makes you a prime candidate for spraying lacquer. NOT brushing. Just clear and clean the immediate areas as good as you can first. Why lacquer? Simple, lacquer dries to the touch and is tack free in less than 5 minutes. Thats only 5 minutes that you need to keep the air clean. How long do other finishes need to be dust/tack free? 4 Hrs? a full day? You can put on all 5 coats of lacquer in the same day. Probably within the same hour.

If you dont want that grainy look, put on a thin sealer coat of lacquer, sand lightly and apply a solvent based wood grain filler.
Unles the rules have changed, a wood grain filler should be applied with a burlap cloth across the grain. One 'along the grain' stroke will pulll some of it out. Follow the directions on he filler can for application, drying and recoat time. Then just go ahead with your 5 spray coats of gloss lacquer, If you want a satin finish you can rub the last coat. If you want to spray a satin coat, spray 4 coats of gloss and spray only the last coat with satin.
You must use a good grade of lacquer like a catalyzed or a pre-catalyzed furniture grade or bartop lacquer. The cheap cabinet grade will not hold up well under usage.

Tony B
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post #10 of 12 Old 10-02-2008, 04:59 PM Thread Starter
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Thanks to you both. That's very helpful information. I'm still on the fence, but will try to do a sample as suggested. This is a picture of the same exact piano that I'm working on, which someone has already refinished. Getting the finish to look like this is pretty much the goal. I've contacted a fellow who was involved in the restoration, but he's not sure if they filled it, then oiled it, or just oiled it. Hopefully he'll get back to me.

http://www.carlsenmusic.com/332.jpg
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post #11 of 12 Old 11-07-2008, 04:52 PM
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Is this the same piano

I saw your post and remembered I had seen that piano or at least one just like it. Here's the link... http://www.balaams-ass.com/piano/mcneel.htm. It says he stripped the finish and applied 10 coats of tung oil. For what it's worth...

Andrew

Last edited by corbin92599; 11-07-2008 at 04:53 PM. Reason: can't spell
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post #12 of 12 Old 11-08-2008, 09:07 AM Thread Starter
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Thanks, that's exactly the goal. I had seen the pic, and hope I can get it there. Project's coming along. Body's totally stripped, have to do some minor veneer repair, then start oiling. I'll put up pics when it's done.
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