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Old 27th August 2002, 01:37 PM   #1
audioPT is offline audioPT  Portugal
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Question Speaker finishment

Hi!

What is the best way to turn a simple MDF speaker on a 'Piano style' speaker?
I've tried a lot of things, but it still opaque, without any bright.
Can any1 help?

Tanks

Nuno
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Old 27th August 2002, 03:10 PM   #2
Vivek is offline Vivek  India
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Hello Nuno,
Try www.lungster.com or www.theloudspeakerkit.com. Hope they help. All the best.

Vivek
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Old 27th August 2002, 03:41 PM   #3
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PT,

Do you mean a high gloss black lacquer finish?

Rodd Yamas***a
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Old 27th August 2002, 03:49 PM   #4
audioPT is offline audioPT  Portugal
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Well, as you must have seen, I'm portuguese and my 'english' isn't very good.

If you refer the high gloss black lacquer finish as the brilliant black aspect of a piano, YES! Is that I want!

You know, I can't find a dictionary to translate 2 words: Glossy and Plywood.

Can anyone explain that?

Tanks

Pedro Nuno Martins, a.k.a. sapito
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Old 27th August 2002, 04:03 PM   #5
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Hi PT,

Glossy is high shine, like a mirror.
Plywood is sheets of wood made of multiple layers of thin sheets of wood glued together. Each sheet has the grain 90 or 45 degrees to the next sheet. This make it very strong.

To get a "piano" black finish you need to spray many coat of black lacquer. Wet sand between coats. When the finish looks "deep" enough for you, finish with 2 or 3 coats of clear lacquer (wet sand between coats). Use 600 grit sandpaper when wet sanding. This will be the same techniques as the auto-body guy use on custom auto finishes.

It's a lot of work.
Rodd Yamas***a
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Old 27th August 2002, 04:29 PM   #6
SteveG is offline SteveG  United States
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you may also need to use a sanding sealer on the wood before you prime and paint. Prep work is the key to a great looking finish- make it perfect with filler and primer before you paint it. Use a few coats of black laquer wet sanding with 600 grit between each one, until you get even coverage. Then use many coats of clear, wet sanding between each. Clear coats are how you get depth. After you have enough clear built up, wet sand with 2000 grit and buff. It should look like a mirror. If you see black coming off on your paper, you are in the color coat. You do not want to sand through the clear coat.
Steve
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Old 27th August 2002, 04:31 PM   #7
audioPT is offline audioPT  Portugal
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I think I'm going to call MOM!!!!!

Ouch! It's a lot of work indeed!!
Maybe I'll send the speakers to anyone who can do it. I think I can't.

Plywood: I use it a lot in my work and never has occur in my mind that. I use it in platforms and boats.

Tanks one more time.

Best regards

Pedro Nuno Martins
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Old 27th August 2002, 04:38 PM   #8
audioPT is offline audioPT  Portugal
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I'm going to tset in a little plate of MDF.

I'll make some holes and fill them with one thing I call 'betume' (don't know the exact word in english) and after it is dry, I'll polish until I get a clean and flat surface.
then I do the instructions all you have told.

I promess to leave here a message with a picture of my 'Picasso'

Pedro Nuno Martins
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Old 27th August 2002, 06:54 PM   #9
SteveG is offline SteveG  United States
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can't wait to see it! Good luck.
Steve
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Old 27th August 2002, 08:44 PM   #10
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From my archives of the BASSList -- i'll clean this up before i put a copy in the Wiki.

Below is a complete post from (former ?) list member Delwin Fandrich
on getting a "piano finish". It was posted 7/21/98. HTH.

=========== Delwin's post below ==============

OK. About that "Piano Finish" we hear so much about. There are two distinctly different finishes being talked about here. The traditional "hand-rubbed" piano finish and the more recent "high-gloss" finish. The high-gloss finish is polyester -- a plastic. Since we don't care for the look that this finish gives to pianos we don't use it and I'm not qualified to comment on its application.

The hand-rubbed finish is usually nitrocellulose lacquer. This material is quite easy to work with, just remember that it is extremely flammable -- explosive even -- so take care. It also stinks and it's not real good for your insides. You will need lots of ventilation, both to reduce the fire danger and to reduce the wear and tear on your lungs and your brain.

The following procedure works for both clear and colored lacquer finishes. If you are using black, I'd suggest using an automotive acrylic lacquer. Especially if you want a high-polish finish. Traditional nitrocellulose tend to look a bit blue or gray when polished out.

Step 1) Surface preparation. All surfaces must be sanded to a dead flat finish. We dry sand with an open coat aluminum oxide paper -- not stearated -- starting (usually) with 120 grit and working up through every grit to 320. When sanding flat surfaces the paper is always used with a firm rubber sanding block. All surface dings, scratches, blemishes, etc., are filled or fixed after the first sanding with 120 grit. All imperfections must be fixed before either the stain or the first coats of finish are applied. (The obvious exception being with a black finish which can be patched at any time.) After the final sanding we "break" the edges to a nice uniform radius using 220 or 320 grit paper backed up with sensitive fingers.

Step 2) If the wood is an open pore wood and the finish is to be closed pore, the next step is to pore fill. Pore filler is a silica base material that is thinned to approximately the consistency of heavy cream and brushed on both with and across the grain. Pore fillers can either be applied in their natural color -- a light creamy tan -- or stained to accent the pore texture of the wood. Once the pore filler is partially dry (the surface is just dull) it is wiped or scraped off across grain. A tiny amount of pore filler will be left in the open pores of the wood leaving the surface quite flat. Allow the remaining pore filler to dry for at least 24 hours and sand the surface lightly with 220 grit and 320 grit dry paper.

Step 3) If the wood is to be stained, now is the time to do it. We also stain the wood of pianos that are going black. It helps later when Johnny runs into the leg with his new toy truck and chips the finish. There are a variety of different types of stains available. Books have been written on the subject. For most amateurs the selection is going to be somewhat limited to what can be found at the local HomeBase or hardware store. These are usually oil based or water based stains. All I can say here is to follow the directions on the can.

Step 4) After the stain is dry apply the first coats of finish material. You can use sanding sealer if you wish, we do not. Sanding sealer is simply lacquer with some additives blended in to make it easier to sand. If you've done your prep work well you won't have to do that much sanding anyway and lacquer without the added stearates bonds better and is more durable.

(Note: If I were putting a black finish directly over MDF or particleboard, I'd first spray on a coat of black or dark gray automotive primer. These are very heavy bodied filling primers designed to fill in rough metal work and leave a fairly smooth sanding surface. It might take two coats.)

We spray three coats of lacquer straight over the stained wood surface. Allow this to dry (we allow 24 hours) and wet sand with 320 grit wet-or-dry paper on a firm rubber sanding block. Don't over do this. You're only trying to knock off the high spots here. Lacquer chemically bonds to lacquer so you don't need to "rough-up" the whole surface. You're getting rid of raised grain, dust particles, etc. (You didn't get any runs in the vertical surfaces, did you? If so, sand them out also.) What you don't want to do is sand through your nice new surface into the stained wood.

Step 5) Spray three more coats of lacquer on the surface. You're more experienced now so you won't get any more runs, right? Again, allow 24 hours of drying time and wet sand with 400 grit paper still on a firm rubber block. This time you want to sand the surface pretty well flat. Always sand with the grain and be extra careful around the edges.

Step 6) Spray on three more coats of lacquer. This time let the surface dry for at least three days. Wet sand, starting with 400 grit paper and working through 500, 600. If this is to be a "hand-rubbed" finish stop here. The final rub is most easily done with plastic wool sheets (the white kind without any built in abrasive) and pumice or rottenstone. If you can't easily find these, good old Ajax will work. So will automotive rubbing compound.

If the finish is to be more highly polished, continue sanding through at least 800 grit. Now switch to polishing compounds. We use 3M, but McGuires (sp?) is more commonly available. Visit your local auto paint store. There are about a million different compounds available and I don't even pretend to keep up with them. Find someone at the store who knows what they sell -- if you can -- and ask. The final polish will be done with a random orbital buffer. These might be available for rent. Otherwise, check Sears and/or head back to your local auto paint store.

The above is not intended to answer all of your questions about finishing wood. It's a complicated subject, but it's not an impossible subject for one who has already figured out how to build a speaker system. If all of this whets your appetite for fine finishing, might I suggest two excellent books:
Understanding Wood Finishing by Bob Flexner (Rodale Press), and
Spray Finishing by Andy Charron (The Taunton Press).

Achieving a fine finish on your work is not all that difficult. It does require some knowledge of the the materials you use and the proper techniques used to apply them. And some patience. Good luck.

Del
Del Fandrich
Piano Designer & Builder
Hoquiam, Washington USA
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