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I'm building some speaker cabinets for my living room out of MDF. I'm wondering how to achieve that "high gloss" / "piano black" look, like on B&W speakers or, well, black pianos...

Any ideas? I'm pretty sure it involves lots of layers of lacquer, but does anyone have any specific advice to give - spray or brush, how many layers, surface preparation, what kind of topcoat?

nippoo
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  • Consider powder coat. Although it will likely be necessary to send it out, it is a very durable surface. – bridger berdel Jun 29 '15 at 15:41
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    ...How does one powder coat MDF? I'm pretty sure that is for a metal only surface? – BrownRedHawk Jul 01 '15 at 14:31
  • THe high end instrument world is probably still lacquer....contrary to what many posters wish they knew. (Other than Violins, which historically have been shellac to my knowledge). I don't know where everybody get's off saying things they know nothing about. I had a lacquer crew in Beverly Hills for a long time. For the most part, the following is true. 1)..MOST, if not all manufacturers ..switched to polymers due to the EPA and lower total finish costs. 2) Polyester is not a repairable finish, whereas lacquer is absolutely repairable...You can try to repair polymers all you want, but it is st – user4587 Dec 16 '17 at 14:15

6 Answers6

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I think the link in LeeG's reply covers all the necessary steps but just to have it spelled out here.

Good surface prep is very important, imperfections 'telegraph' through paint very easily so the more perfect you can get the surface initially the better. The flatter the starting surface the less paint you have to use too, so it does have both time and cost benefits.

Build up of colour in multiple layers. Just as with most painting and varnishing multiple thin coats are better than one thicker coat.

Flattening off using a sanding block to maintain a good flat surface. Special care must be taken at edges and corners as it is very easy to sand through to the primer coat.

Final smoothing by wet-sanding to a very high grit, while still striving to keep the surface flat; it is possible to introduce waves and other dips into the finish even after switching to very fine grits.

Polishing. This can be achieved in any number of ways, from the old traditional methods used in furniture finishing such as using powdered rottenstone lubricated with a light oil or water, to modern cream polishing compounds and powered rotary polishers.

Graphus
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  • Which type of polishing compound? Ones that are used for cars? – basickarl Feb 15 '21 at 11:35
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    @basickarl, actually nearly anything that's fine enough (dry, creamy or in liquid form) but yes you can use stuff sold to polish car paintwork. – Graphus Feb 16 '21 at 09:30
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I have used this guy's technique before and it works great.

Basically, you apply very thin coats, then sand to about 400 grit, and after that, do wet sanding to about 2000 grit, and then switch to the polishes.

There is a pretty complete step-by-step here

LeeG
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    nice link, in his photos you can see a slight pebbly texture to the finish. This usually means the paint was drying as it hit the surface, so adjusting the distance of the spray will help reduce that, which means less work with the sand paper. Piano finishes are lacquer applied via spray gun (see http://www.stewmac.com/How-To/Online_Resources/Finishing/Spray_Guns_Getting_Started.html) Often a clear layer of finish is applied as well for protection and visual depth. – ewm Apr 04 '15 at 13:18
  • The photos in the link are not visible as the photo hosting has run out. – Henry Collingridge May 09 '20 at 21:29
  • Which type of polish compound? – basickarl Feb 15 '21 at 11:34
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It seems nobody bothered to mention French Polish. Sigh. That is the standard piano finish for quality pianos, period.

French polish is a series of steps that fills and smooths surfaces using shellac.

Over a stained and filled (grain filler) prepared surface:

The first step uses rottenstone (like pumice) mixed with 1/2 lb or 1 lb cut shellac; rottenstone comes in grades (particle size). You work through grades of rottenstone + shellac from coarser to finest. The final multiple passes are shellac only.

The reason this is not used more often is not the quality of the result, but the cost of paying someone with experience to do it. Mass produced pianos would have to be finished in places where wages a far lower than Europe or The US in order to compete price-wise with other finishing methods.

I've touched up some baby grands and estimate that one square yard of surface is about two hours of work for minor touch up. I do not know firsthand, but am told a full grand piano can take 160 man hours or more for all finishing steps.

The good part about french polish is that it can be touched up to look completely new, but damage on nitrocellulose lacquer may require complete refinishing. By damage I mean spills, not where little Tommy takes a hatchet to a piece of furniture.

Pictures do the best job of conveying the idea: https://www.youtube.com/watch?v=LqYENoVuySo

jim mcnamara
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    Shellac is no longer the standard finish for quality pianos because although it gives a beautiful gloss it doesn't provide the same level of protection as varnish or lacquer, both of which have the additional advantages that they are easier and faster to build up. – Graphus Jun 23 '15 at 07:04
  • Could you expand a little bit more on what the French Polish is in your answer? As it is, you basically have a link only answer which will get deleted. – bowlturner Jun 23 '15 at 12:53
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    While I agree with @Graphus I do like to see the traditional method/products mentioned. – James Jun 29 '15 at 16:51
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I know this is an old topic but hopefully this helps someone out.

Painting MDF can be very frustrating. End "grain" in MDF will soak up paint faster than you can apply it.

Sand that with 320 then 600 then 1200. I use a tinted oil base primer. 3 coats block down with 400-600 and repeat until the end grain no longer soaks up your paint and has the same look as the face of the panel.

Now you can paint. I have had good luck using Nason 2 stage automotive paint (base coat/ 2k clear coat). The important part is before the paint.

Here is an example finish

dr biz
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If you're using MDF spray it with epoxy primer blocks sand it and shoot it with black acrylic enamel if it doesn't appear flat enough blocks and sand it with 320 grit sandpaper shoot it again then buff it this is far easier and faster I restore old wood boats

Bill
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All high gloss pianos are polyester. They are not lacquer of ANY stripe, nor are they shellac. Neither lacquer nor shellac can look good for long, except they be cared for tremendously meticulously.

Polyester is a 100% solids, vastly harder than lacquer, and can be built ten times thicker than lacquer without cracking. It takes serious buffing equipment, and quite a learning curve.

For black, contact Allied International (http://alliedintlinc.com); for clear, find a nearby Duratec dealer. (Only Allied has a true piano black; others have a blue cast.)

Joel Lidstrom
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  • This is patently false. Not all pianos are poly. There are plenty that are shellac and lacquer. I won’t bother explaining who what when and where, the information is freely available. I have worked on pianos in my uncle’s shop restoring Steinway’s and others. – Jared Aug 09 '22 at 10:13