piano black or other high gloss finishes on MDF

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First things first.

Preparation: nice clean sanding, round edges il you like.
Seal the porous matierial with a sealer.
Then apply a coat or two of a good oil paint primer.
And the secret ingredient.-----The PAINT, THE GUN AND THE ELBOW POWER.
I recommend a good Epoxy\PolyUrethane black\ hI GLOSS
The oil paint is pretty good at leveling out into a fairly smooth finish.
You can make the surface even smoother by lightly wet sanding between coats with a 400 grit sandpaper. The wet /dry sandpaper is black, and usually comes in 200, 400, and 600 grits. You use this paper by applying a little water to the surface, and then lightly sand the surface, all the while keeping the surface wet. Wet sanding allows you to quickly sand the surface, all the while keeping scratches to a minimum. The top coat of black, applied evenly, will dry pretty smooth. Let cure Overnight each in between coats.

I Recommend these for starters.
http://www.princessauto.com/air/paint-guns/8142481-3-pc-hvlp-spray-gun-kit?keyword=gun+paint

ps: Use with 20% or less dilution
If you want to push it further, and make the surface even smoother, then you can, after wet sanding with the 600 grit paper, take some automotive rubbing compound, and using either a power buffer or some serious elbow grease, buff the surface, removing any visible scratches. The finish will now be smooth, though with a slightly hazy sheen. Use some automotive polishing compound to remove the haze and bring up the shine. The more time spent on this step, the greater the gloss.


Please Post some photos when u are done!

Marc
 
Some advice from a cabinet maker:

Paint whatever color you like on a well sealed and sanded cabinet. Sand the color coat to a smooth finish at least 320 grit.

Here is the evil trick I have used for almost 20 years. Use 2 part epoxy thinned with acetone. It will set quickly and give you depth like you wouldn't believe.
Every epoxy maker is slightly different in their mix but they almost all thin with acetone. I use stuff that sets up in an hour and when it is sprayed it sets up very quickly.

You can wet sand and rub out the epoxy coat to what ever sheen you desire.
ShinOBIWAN has good details on sanding and rubbing out the finish.

The only thing I would add is I use a glass backed sanding block. It gives a ripple free dead flat finish. And no you can't buy one. Get the appropriate size piece of glass cut and use silicone caulking to bond it to a wood backer. I sized mine so that a 1/4 sheet of paper was easy to hold on to at the edges of the block.

A few drops of soap in the water when wet sanding helps a great deal to.

Mark
 
Here is the evil trick I have used for almost 20 years. Use 2 part epoxy thinned with acetone. It will set quickly and give you depth like you wouldn't believe.

Would it be similar in appearance to a "gel" coat finish? I'm not certain that's the appropriate term, but that's what jumps to mind when someone mentions that a painted finish has "depth".

The only thing I would add is I use a glass backed sanding block. It gives a ripple free dead flat finish. And no you can't buy one. Get the appropriate size piece of glass cut and use silicone caulking to bond it to a wood backer. I sized mine so that a 1/4 sheet of paper was easy to hold on to at the edges of the block.

A few drops of soap in the water when wet sanding helps a great deal to.

Mark

I've heard the soapy water trick from a buddy that does body work professional. How well would the "glass backed" block work on a curved cabinet though...? I would have to think the small amount of surface contact would do more harm than good...yes/no? Give you something more of a ribbed finish?
 
Would it be similar in appearance to a "gel" coat finish? I'm not certain that's the appropriate term, but that's what jumps to mind when someone mentions that a painted finish has "depth".

Yep. But any well done gloss finish will give you the proper depth. The method I've told you about does it with the least amount of effort. You pay more for the finish and the learning curve. Practice before you try this. When you get it you will never turn back.

I've heard the soapy water trick from a buddy that does body work professional. How well would the "glass backed" block work on a curved cabinet though...? I would have to think the small amount of surface contact would do more harm than good...yes/no? Give you something more of a ribbed finish?

I think you answered your own question.

Flats need a flat reference. Glass is flat to a few .0001". But as you pointed out it doesn't curve very easily. Your hands will do the trick. If it is a uniform curve and it really matters you can make a form but that is very rare.

Good you have a buddy who knows how to spray. He'll be good for more than one tip I'll bet.

Mark
 
How well would the "glass backed" block work on a curved cabinet though...? I would have to think the small amount of surface contact would do more harm than good...yes/no? Give you something more of a ribbed finish?

No, it is when you abandon using a flat rigid support that you start to get problems. Do not attempt to sand with the paper unsupported in your fingers.

MDF as manufactured has a fine-textured finish on the faces of the boards. It is preferable not to scratch this finish if at all possible. This means that some mating parts cannot be sanded in place. The finish on worked edges will have a more open, absorbent nature. The problem is to dimension the parts so that when sanding sealer is applied to the assembled whole the joins are undetectable, preferably at the first coat. Sanding sealer is a sugary easily-worked varnish that can be built up quickly to conceal flaws. It sits on the surface and stops other paint sinking in but it's easily worked nature makes the finished article more prone to dings if applied thickly. You need enough on there so that you are not sanding into the fibres at any point, however, as they may start to 'pick up' and make the surface furry.

w
 
No, it is when you abandon using a flat rigid support that you start to get problems. Do not attempt to sand with the paper unsupported in your fingers.

Well I wasn't suggesting the use of "unsupported fingers", but more so expressing concern with having a rigid flat backer when sanding curved enclosures. The hard backer will only allow a very thin area of contact at any given point during the sanding. This, I believe, will increase the likelyhood of over working your finish.

MDF as manufactured has a fine-textured finish on the faces of the boards. It is preferable not to scratch this finish if at all possible.

Unfortunately in my example it's very unlikely to have a "virgin" face to work with. The large bulk of curved enclosures using MDF are of a translam construction. So the majority of the finish process will be done on worked edges.
 
I'll post my experience going through this process:

I did a little research and talked with a good HVLP painter and found out about a cheaper and faster solution. M.L Campbell makes a really nice primer called Clawlock which is designed specifically for use with MDF. They also make a great varnish called Resistant. Both are super thick (45-55% solids formula) and require a catalyst to use. Also you don't require a clear top coat using this method. The advantages of going this route are: a fraction of the coat needed to achieve a good result, the paint is much more durable and because it's pretty solid it's harder to make a critical mistake when sanding or polishing and it's much more water resistant then just about anything on the market. You don't have to worry about jerks leaving cups on the speakers, lol.

One of the speakers before the paint and the stain:
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I prep sanded with 400p, and I did every surface. I would suggest using 3 layers of primer and 3 of varnish, sanding every 2 layers. So 2 of primer, wet sand with 600p, 1 primer and 1 varnish, wet sand with 1000p and finally 2 layers of varnish and leave the paint to cure. They suggest not using more then 2 layers of primer and 2 layers of varnish but I talked with them and if you sand down as suggested above you'll be ok. You just don't want to have the paint be so thick it'll crack once it cures. They are oil based, so you'll need a good mask and a well ventilated area. They suggest waiting a month for the paint to cure but I decided on 2 just to be safe.

First couple of layers of primer:
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Sanding after the first 2 layers:
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My camera died on me at that point, so I don't have any of the second sanding stage. Here's the final layer of paint tho:
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Post paint job results:
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I waited 2 months before I started the final polish. I wet sanded with 2000p, but I'd suggest getting some 1600p to start out with, it'll save you a lot of time. This paint isn't like sanding a clear coat. I was able to get pretty aggressive with the sanding, but I was doing it by hand with a rubber block. You just want to sand until the surface looks like metal while dry. There were little dimples in the paint, you couldn't really feel them but when dry they were visible. I just sanded till they were all gone. Once you've sanded all the sides it's no different then what ShinOBIWAN suggests in the 'how to' thread. Just polish with the G3, I did 5 layers, and finish with the car polish.

Applying the G3:
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I'd never done this before and I'm not tool savvy but it wasn't too bad. It takes a lot of time and energy, but you can't argue with the results:

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What I can do is say beautiful job. And I can't believe you sprayed inside! Oh what a smell.

My only comment that is more of a question is do you think that the choice of solid wood baffle is wise? MDF has near uniform expansion across the face in every direction. The wood baffle has about 2.5% expansion vertically and about 8 to 12% across the width if it is oak. It maw work it may crack itself off eventually. I personally only use veneer on cabinets for loudspeakers. It behaves itself guaranteed.

Mark
 
What I can do is say beautiful job. And I can't believe you sprayed inside! Oh what a smell.

My only comment that is more of a question is do you think that the choice of solid wood baffle is wise? MDF has near uniform expansion across the face in every direction. The wood baffle has about 2.5% expansion vertically and about 8 to 12% across the width if it is oak. It maw work it may crack itself off eventually. I personally only use veneer on cabinets for loudspeakers. It behaves itself guaranteed.

Mark
I had some oversight from my friend who's built a lot more of them then I have and his wood working friend and they gave me the thumbs up. They work with MDF and oak a lot more then I do so I'll defer to their experience. I think they should be alright.

Also, I did spray inside but it was right next to the exit to the garage with a fan sucking out the fumes. My biggest concern was temperature. It was close as hell that week and I wasn't going to ruin the paint over that.
 
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I've made a few piano black speakers... I've learned a few things.

Bondo the seams. Spread it wide on the seams so you can feather the edges so it is flat. If you just put a small line of the seams it will just round over or sand right off. Make them perfectly flat and smooth by block sanding 80 grit. If you sand with higher than 80 grit initially you effectively "polish" it and it rounds over.

If the seams aren't perfect, they will show through all your paint and it will be a wreck.

I did a center speaker and used wood filler on the seams and they have all shown through and it doesn't look that good any more. I also blame the zinsser bin primer for contributing to the seams showing through, as well as using lacquer from a spray can as the finish. HVLP is so much better as it paints better and you can use high quality paint.

Use a high build primer. A lot of people recommend zinsser bin as a primer but I would advise not to use it if you are trying to get a gloss finish. I have used 2 part urethane high build automotive primer recently and it is very, very good.

If you have it perfectly bondo'd, then paint it properly, it is fairly easy to get it to be piano black as all you have to do is polish it either with high grit wetsand or automotive rubbing compound/polishing compound.
 
Here’s couple tips if you are looking for a “show quality” gloss black finish. It really doesn’t matter if it’s furniture or a show car. The base surface must be as close to perfect as possible. This involves a lot of block sanding and filler of the appropriate type, whether it is body putty and high build primer, or a wood filler and urethane primer.

Block sand and fill, block sand and fill, block sand and fill---until it’s perfect.
A tip to determine if the surface is perfect: wet the surface (don’t use water on bare wood) and place a common 2 bulb fluorescent light fixture horizontally above and to the side to the surface, and move your head back and forth (or side to side) and look at the reflection of the lamps. Every imperfection will be visible, as a distortion of the straight lamp tubes. Anything you see now will look worse when you are done!

Two stage polyurethane or catalyzed lacquer is “light years” ahead of any other material you can use. Have a professional spray the item(s), as use of these “paints” requires experience and proper ventilation. This doesn’t have to be expensive. I recently had two medium sized speaker cabinets sprayed with catalyzed lacquer at a local cabinet shop for $30 total, including materials.

Wet sand with “wet and dry” sandpaper wrapped around a putty block, which is a flat 2X4” piece of flat rubber with square edges. Rinse out the sandpaper often in a water bucket. Start with 600 or 800 grit. Next, do the same with 1200 grit. Finish up with 1600 or 2000 grit paper. Never sand with your fingers or bare palm—always use the putty block, even on curved areas. To check the surface, wet it with a sponge, and lightly drag the square edge of putty block over the surface. This will reveal areas that were missed or need additional sanding. The fluorescent lamp trick helps here also.
Power buff with medium to light compound. Power buff or hand buff (lot of work) with automotive polish to remove the swirl marks.
Clean up and you are done! The finish will probably out-live you!
DO NOT apply any kind of wax to this finish. Properly done, you cannot improve upon it.
 
Products I like to use for the rare times I paint speakers are from the M L Campbell product line - Clawlock catalyzed primer and either Resistant tinted Conversion varnish or Magnamax lacquer, and for extra durability, a couple of topcoats of Krystal post catalyzed conversion varnish. All of these products are specifically formulated for the cabinet / millwork finishing trade.

As ArtG notes above, there's no substitute for scrupulous preparation, the right products and experienced skill with the application equipment.

I've said this before - the final tally on and materials to achieve a "show grade" paint finish can make the cost of all but the most exotic veneers and simple clear top coats pale by comparison, but certainly there are shapes and profiles that lend themselves to nothing else but solid colours.
 
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