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-   -   piano black or other high gloss finishes on MDF (http://www.diyaudio.com/forums/construction-tips/159792-piano-black-other-high-gloss-finishes-mdf.html)

mondogenerator 23rd January 2010 09:07 PM

piano black or other high gloss finishes on MDF
 
anyone have any ideas on how to achieve a high gloss piano black or other coloured finish to MDF?

Im considering car sprays/primer and alot of sanding....is there any other products which may help me achieve a good result?

stephenmarklay 24th January 2010 02:35 PM

I am sure it is in the preparation as much as the final coats. I think there was a thread on PE that talked about it.

Bluto 24th January 2010 02:49 PM

Mondo -

I know there's several good posts here so do a search. If you Google you'll find one that's a few pages long; had it, lost it.

Lot of work to get that 'mirror' finish.

tvrgeek 24th January 2010 02:55 PM

After doing a pair and spending days primering, I learned to resin the MDF first with polyester resin. I used Dupont Centuri.

smokinghot 26th January 2010 11:17 AM

...and with a quick cut'n'paste of :wchair: Mondo's request, "high gloss finish" into the forum search bar....

:wiz:

http://www.diyaudio.com/forums/const...finishing.html

trd1587 18th February 2010 07:38 PM

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/pain...word=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

mwmkravchenko 18th February 2010 10:13 PM

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

smokinghot 18th February 2010 10:51 PM

Quote:

Originally Posted by mwmkravchenko (Post 2090226)
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".

Quote:

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?

mwmkravchenko 18th February 2010 11:31 PM

Quote:

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.

Quote:

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

wakibaki 19th February 2010 12:02 AM

Quote:

Originally Posted by smokinghot (Post 2090260)
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


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