Rubbing Out a Piano Finish
The fine points of creating that smooth, even sheen on a black grand piano. December 27, 2006
Question
I'm rubbing out a piano sprayed with black lacquer. The lacquer was left to cure for 6 days prior to rubbing, and I already know about moving up from 320 wet/dry through the powdered stones and polishing compounds, so achieving a leveled, high-shine finish is not a problem for me. The issue is in achieving that finish without a streaky look. Common sense tells me that if the finish looks striated or streaky, there must be unevenness in the rubbing pattern, where some spots are duller (more scratched) than others, but I'm being very even in my paper and felt-block strokes, and it's still hard to achieve an even look in a black finish. This is all by hand - must I use a power-buffer?
Forum Responses
(Finishing Forum)
From contributor R:
I found that rubbing out a clear coat over an opaque coating will yield a less streaky look. Rubbing by hand will for sure leave trails; no way around it. If you're bound and determined to do all this work by hand, you might have to live with the look. Steinway pianos done in satin have that streaky look and they achieve that with 4xxx steel wool. Since you are rubbing a black coating, you might try a product called Liquid Ebony. It is black in color, and made for rubbing a coating that is black. It is usually performed by machine, but I have had good success applying it by hand.
From the original questioner:
Thanks for your info. Liquid Ebony sounds like a cool possibility. Unfortunately, I Googled it and it seems to be a discontinued product. Its parent company, Cleanbright, seems to be out of business. I have plenty of 4X wool, and could satinize like Steinway, but I was hoping for a higher gloss than that. And unfortunately, it would not be ideal for me to go back over the finish with clear topcoat at this time, and restart the rubbing process. And no, I'm not determined to do all by hand, it's just that I don't own a buffing machine of any kind at this time, and was hoping to avoid investing in one, unless there was a decent one for not too much dough. Any suggestions?
From contributor D:
Have you tried going to maybe 400, then 600 grit in your wet sand? 320 seems pretty aggressive to start on a black f/g finish!
From the original questioner:
I actually started with 220, because the orange-peel was taking forever to level out with 320, and this is a grand piano - lots of surfaces to cover, and my arm was wearing out. So I leveled with 220, then 320, 400 and so on. Since each successive grit should successfully round out the edges of the lower grit's scratches, I don't know why there'd be much problem starting lower. It's not like, when I look at it now, there are any 220-depth or 320-depth scratches left; the remaining brushes look more like 600 or higher.
From contributor C:
You need to understand that black finishes are very fluffy... They are very heavily pigmented and soft. In most cases, they do not rub out well at all! Usually I level them and then recoat with a clear finish, which is later rubbed out to the proper sheen. 600 grit is a long way from smooth enough. I have had good results by working from 500 grit through 4,000 grit with
Abralon discs (on my random orbit sander) and then using a couple of grits of polishing cream by hand followed by waxing (with paste wax or acrylic). Another option is to use a finish which is designed to be rubbed out (such as Arthur Grudko's "Piano Lac").
I suspect that your finish is so soft and fluffy that there is no way in heaven you could get it to rub to a high gloss as it is now. The reason that I usually apply clear coats and rub them out is to gain density and finer grain in the top surface area. I usually guesstimate that I am gaining a hardness and density level that is about 2 to 4 times what I had when I leveled the black coats. Too soft a surface just will not rub out to much of a shine, no matter how you do it. Even the softer stones are too soft to take a decent polish.
From contributor O:
Trying to rub out a pigmented finish is, at best, self-defeating. As per contributor C, only rub out a clear coat.
From the original questioner:
I'm learning a lot - thanks. I never considered the softness of black due to high pigment content. Guess I'm going to have to find the time to put some clear coat over my current finish and rub that when it's hard enough... How long do I need to wait for a clear lacquer coat to be rub-out hard?
By the way, I got an electric buffer (they're not expensive at all). I ended up with a 10" orbital one with big circular handles. So I guess this puts me into a whole new category with choosing abrasives and polishes to finish the finish.
From contributor C:
Do a bit of research before you put on your clear coat(s). Select a finish with good rubbing characteristics (most fare poorly). Check the archives here for recommendations. I only do rubbed out finishes on rare occasions, so I am not the best source for specific product names. Fuhr, Target, Arthur Grudko, Jeff Jewitt are all good contacts to check with. Or ask your local finish rep for his recommendation. Your new buffer will help a lot, but be careful to avoid melting the finish with too much pressure and too much time in one area. You'll still want to level with your sander before buffing.
From contributor M:
For a conventional lacquer, 1 week is not enough cure time if you are going to use a buffer. A 2k poly would be a better choice. I like 3m microfinishing film for my sanding. It's available in standard grit sizes or micron sizes. I use a DA for my wet sanding and lamb's wool pads for polishing. Catalyzed finishes can be buffed out much sooner. That's why they use them in automotive painting. A conventional NC lacquer could take as long as a month to cure and shrink before buffing.
From contributor Y:
Baldwin Pianos use ILVA brand finishes. I believe they use the polyester over a black basecoat, then sand level, then ILVA's 2-part acrylic urethane clear topcoat. ILVA products are available from their US distributor, IC&S in Lancaster, PA. I use these products too, and they sand and buff like a dream. The higher grit sandpaper you start with on your last topcoat, the better results you'll end up with. You should be pretty well level before the topcoat, anyway. I recommend starting with 800 grit on your last coat, and sanding up in steps to 2000 (800, 1000, 1200, 1500, 2000) before switching to buffing compounds (Menzerna medium, then fine - check out Grizzly's catalog). Sometimes I'll wet sand 2000 and 4000 with the excellent
Abralon foam discs before buffing.
It doesn't take long with an orbital sander (electric or air-powered), as you are not leveling, just removing scratches from the previous grit. Save your arm and use a power tool for the sanding! If you go through these steps and are sure to get the scratches out from the previous grit, you'll end up with a super high gloss finish after the final buff!
From contributor E:
I had a customer do a full gloss black kitchen in the ILVA several years ago with a full rub and it looks great to this day. Two coats of 2K poly undercoat and 2 coats 2K black topcoat. It was not an easy finish, but can be done!
From contributor K
Very often, the streaks are from uneven pressure in your rub strokes or worn rubbing materials. Try to avoid pressure from fingers and keep track of the wear on your rubbing materials. Use fresh paper and wool. I really like the Liberon wool. Finishing with the Liberon 4 ott wool and lubricant will give you a very nice sheen, definitely glossier than the Steinway factory sheen.
I would not suggest topcoating a NC lacquer with a catalyzed material. NC lacquer can rub very well with the correct schedule and materials. If you started sanding the final coat with 220, you might have a hard time sanding those heavy scratches out with the next grit. If you need to sand with 220 to level your surface, you should consider a review of your finish building schedule. 220 scratches usually need to be topcoated. With that said, you can bring a 220 sanding to a rub-able sheen, it is just way too much work. Once a good final coat is applied, you should be able to remove any finish shrinkage with 500-600, then 800, before moving to wool.
Each rubbing stage should be uniform before moving up to the next finer grit. It is absolutely possible to rub the whole job by hand. Machines are nice, but not absolutely necessary. I do 75% of my piano rubbing by hand.
