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Piano fininsh on walnut

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Forum topic by troyercar00 posted 07-29-2011 05:15 AM 1420 views 0 times favorited 7 replies Add to Favorites Watch
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troyercar00

21 posts in 1639 days


07-29-2011 05:15 AM

I am finishing a lecturn made from walnut and need some advice. I want to get a “piano finish” that will be very durable. I have done the BLO and pumice to fill the grain and now I am not sure what to use for the top coat. Should or can I use gloss poly or shoud I use a shellac or some kind of oil based poly, I quess my question is can I use a water based or an oil based top coat? Thank you for any help. I really enjoy this site and all the projects and forums. It has been very helpful in my attempts at woodworking.


7 replies so far

View michelevit's profile

michelevit

11 posts in 1542 days


#1 posted 07-29-2011 05:43 AM

I’ve sprayed a piano finish using automotive clear coat. I use a cheapo Harbor Freight Hvlp gun and a small harbor freight air compressor. The product I use is Transtar Qwick Clear it dries super fast and hard. You can sand and polish an hour after spraying. I recommend using auto clear coat piano finish over any traditional wood working piano finish method.

http://www.levineautoparts.com/trkwglacurcl.html

I haven’t seen any information online about using automotive clears on wood, but I have done it and it works great. I spray enough to bury the grain and wet sand up to 2000 and then hand polish with a automotive polish. Bullet proof finish too.

View ajosephg's profile

ajosephg

1860 posts in 2312 days


#2 posted 07-29-2011 03:10 PM

I’ve accomplished this with oil based gloss poly. Be patient, it will take many coats.

-- Joe

View vicrider's profile

vicrider

178 posts in 1649 days


#3 posted 07-29-2011 03:58 PM

For large flat surfaces, I have used the auto clear coat method like michelvit. I have a 5 year old Brazilian Walnut table that you can still see your face in. Multiple coats in a few hours, and quickly move to wet sand, buff, and polish. Very tough and flexible finish which can be re-polished.

Caveats? You need to mix base and catalyst in small batches cause its only workable for about 45 minutes. The thinners (called reducers) are specific for temperature and humidity, it may take a while to learn the exact mix you need. And it’s expensive. The product I used was about $100/qt plus a gallon of reducer.

Did I mention it’s expensive?

I do like the grain filler method that I reviewed here.

I have also used gloss poly over filler with good results, but, in my experience, it takes several coats, and you need to let it dry for a week to get the best polishing results.

I don’t recommend shellac for high gloss due to its labor intensive process. The biggest advantage of a high gloss shellac finish is, it is easy to repair. But so is the auto finish and it’s lots tougher.

Vic

-- vicrider

View Earlextech's profile

Earlextech

1024 posts in 1441 days


#4 posted 07-29-2011 04:40 PM

At this point I would seal with shellac, two coats, then top coat with your choice. The Qwick Clear is a good choice.

-- Sam Hamory - The project is never finished until its "finished"!

View Tennessee's profile

Tennessee

1565 posts in 1265 days


#5 posted 07-29-2011 07:27 PM

Basically, what michelevit and vicrider are using is a nitro lacquer. It dries hard and fast. But, if you can move fast enough, it will gloss like a mirror. Another advantage to nitro lacquer is you can go back within a very short period and polish with 600 grit up to 1000 grit, and respray. I use this on guitars, and it comes out like a mirror. I’ve also been able, (after a day or two), to polish it beautifully with Novus #2.
The drawbacks: It’s gonna be thin. Water may turn it white. It will scratch easier than poly. But if this will be something that will only see use on the top, or paper surface, you should be good to go and save a lot of time over the long wait of many coats of poly.

-- Paul, Tennessee, http://www.tsunamiguitars.com

View michelevit's profile

michelevit

11 posts in 1542 days


#6 posted 07-29-2011 11:00 PM

I think people consider a piano finish as a smooth high gloss finish typically seen in a grand piano. They are typically black in color. Also know as a French polish. The finish is mirror smooth and perfectly flat.

View vicrider's profile

vicrider

178 posts in 1649 days


#7 posted 07-30-2011 07:56 AM

Hi Paul,

I am not describing nitrocellulose lacquer, nor catalyzed lacquer. What I am describing is auto body clear coat catalyzed polyurethane enamel. It does not turn white with water, it is not thin (three coats will build a finish that looks like you can sink your fingers into it), when cured it is very hard and difficult to scratch (although it WILL scratch like on a car, but most scratches will sand and buff out without re-coating). In forty years of finishing I have found it to be the most durable finish I have ever used, but it does have its downside as described in my previous post. Here is a picture of the Brazilian Walnut table I described in my first post, taken after one year of use. In this pic you can see some finger prints but is still very high gloss. It has now been about 5 years and it could use some polishing.

I used lacquer for many years, long enough to have to strip and re-finish several pieces after the lacquer degraded with time. It is easy to use, not very expensive, comes in different glosses, and dries very quickly. However, over time I became discouraged with the lack of strength and durability. It is basically a quick finish for pieces that are not expected to last years and years, like kitchen cabinets and lots of manufactured furniture. Catalyzed lacquer is about 50% harder and lasts longer; it is less susceptible to water staining. It is more difficult to use than regular lacquer, requiring different reducers and has a shorter pot life.

For my high quality pieces, I now prefer regular polyurethane in semi-gloss and gloss. It is affordable, has a longer open time, cures hard, resists water stains, and can be easily thinned with standard paint thinner for spraying. It takes several thin coats to build to an appropriate thickness. It does take longer to dry, and for a high gloss you need to wait several days before final polishing. It takes that long for the thinners to fully evaporate and the solids to harden enough to polish correctly. I have found it to last a very long time, and take a lot of abuse before needing refinishing. The trade-off with auto enamel is time invested against materials cost.

Free advice; If your spraying finishes, don’t breathe ANY of this stuff, use a high quality respirator.

Vic.

-- vicrider

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