[Edgar77]

Sooner or later I will build a couple of Danny's speakers. It seems the recommended material is MDF and all the flatpacks are all made from MDF.

I try to find clear instructions how to paint MDF. It seems when I read 5 instructions or watch 5 videos I see about 6 "solutions".

What did you use? What works? What are the recommendation of the professionals?

Here are some points of discussion.
It seems it's a good idea to start with a MDF primer. It seems everybody agrees on that.

Then the question is which paint? Water based or oil based? Acrylic? It seems there are many different sorts of paint.
It seems oil based paint has lots of disadvantages and many people recommend water based paint.
But then some say water based paint is bad for MDF because of the moisture. But it seem that is no problem if the right primer is used...

And how to paint? With a brush, a roll, spray paint?
Sanding in between or not?

And what kind of finish?

Personally I have black paint in my mind. Maybe shiny like a piano or maybe matt, not sure yet. I want a flat finish, not what some people call orange peel. Personally I don't care about the wood look so currently I don't think about any veneers.

In case you think this is a topic for a painters forum I am glad to see a link or two.
I tried to research this already but there are just too many information and too many opposite recommendations out there. This is why I ask.

Thanks

[hawkeyejw]

I used water based kilz and found the key was sanding well between coats. It’s important you reach the point where the texture of the edge matches the sides perfectly before you apply the final coats.

I recommend spraying if you have a decent gun. Piano will take a lot of additional work after you’ve painted to rub out the finish. Matte is easier if you can get a nice evenly sprayed coat. Some people have gotten good matte finish out of a can but I found it impossible. It always looked uneven until I used a good spray gun.

[sortner]

I just finished some tripple's 12 OB subs and NX-Otticas and went for it with a two stage base coat clear coat.

I used two coats of De-Waxed shellac to seal the MDF, followed by a lot of sanding. I used a house brand paint from a local paint supplier call Lumabase for the base (black) and a Lumabase Clear coat......Probably over board but I put three coats of base and then three coats of clear.. Prior to painting I applied a high build primer from the same company and here's the secret. You must sand very good to get a good result. I will say it takes a lot of work with wet sanding and polishing but you can do it.

I also purchased a Harbor Freight HVLP gun for the primer and a Eastwood higher end gun for the paint (not necessary)

I had never sprayed automotive paint that way and the end result surprised me, it turned out as good as I could hope and as close to the muti thousands people are paying to have theses painted.

I you have the space and willing to put the steps in you cam make MDF look like glass..

Good Luck

Steve

[Peter J]

Admittedly, painting MDF is a huge subject where opinion and hyperbole know few limits. A clear, realistic view of both one's own abilities and desired results is a good start. Measuring your own resolve and $$ resources is also useful.

FWIW, the biggest obstacle I see with painting MDF is dealing with porous "end grain".  Don't make the mistake of willy-nilly mixing and matching techniques, products and methodology. Choose a path and be happy. In industry, there's no new wheel to be invented. But outside of that, it's fodder for many, many, discussions on forums and YouTube videos.

 Like anything, there's more than one path to get to a similar end.  I don't pretend to know it all, but have experience with a lot of different things in the finishing world, and will try to answer questions without bias, or at least tell you what mine are. It would be a nice thing if we could just "buy the best" and be done, but there's way too many variables to make that a realistic possibility.

[Edgar77]

Admittedly, painting MDF is a huge subject where opinion and hyperbole know few limits.

It seems that makes it a perfect for audiophiles.

[jules]

Personally I have black paint in my mind. Maybe shiny like a piano or maybe matt, not sure yet

That might be the key question here. If you're aiming for a mirror finish, you'll be doing much more work than something less revealing [to use a favoured audiophile term  ]

I've done a few jobs where I simply used paint in the same colour as the room, applied with a roller. Once again to use an audio analogy, the speakers "disappear" into the room without even turning them on.

As far as moisture goes, if you can keep your speakers away from dank corners they shouldn't suffer from dampness in the first place plus of course, the drivers won't be painted so they need to be kept in a dry place too for best longevity.

Most of the solutions you find will probably be right if they're matched to the circumstances/user requirements.

[rtate]

Has anyone ever tried epoxy resin type finish ?
Something like this :

https://www.youtube.com/watch?v=ea4NAiDsNIg

Might look good on my nx-otica mtm's   

[WireNut]

Has anyone ever tried epoxy resin type finish ?
Something like this :

https://www.youtube.com/watch?v=ea4NAiDsNIg

Might look good on my nx-otica mtm's   

I've been using West System Epoxy and Fillers since the 80's. Great stuff.
https://www.westsystem.com/

[Peter J]

Has anyone ever tried epoxy resin type finish ?
Something like this :

https://www.youtube.com/watch?v=ea4NAiDsNIg

Might look good on my nx-otica mtm's   

Epoxy pouring is a specific technique and products. You'll notice in the video he's pouring on a a flat and level surface.

I can imagine a rotisserie of some kind to pour finish a speaker cabinet, but it wouldn't have the same visual result. To keep drips from forming I suspect one would need to slowly rotate cabinet until the epoxy firms up. I shudder at the variables involved in what you're proposing, but would certainly watch a video of the effort.

You can get a swirl effect with paint, but you're working with a different methodology. 

I like trying new things, but a clearly defined idea and willingness to experience failures is kinda part of the deal. Perhaps experimenting on something first would be prudent before you jump in on you NX-Oticas.
 

[rtate]

I was thinking that I could apply the finish before assembling the Nx-otica mtm flat pack on a flat surface ?

[Peter J]

I was thinking that I could apply the finish before assembling the Nx-otica mtm flat pack on a flat surface ?

You'd have to devise some way to keep epoxy out of key areas or plan on removing it after the fact. Assuming Jay's flat pack, the rabbets at vertical edges where wings set in comes to mind. Then there's finishing the backside...

I'm not saying it's not possible or that you shouldn't try, but a comprehensive game plan would seem critical, but perhaps that's just me.

[JWCoffman]

Please note before reading that I'm not saying you shouldn't try this, but you should know there are some risks involved you need to understand how this stuff works and behaves.  Also, I've only used epoxy with composites either within a matrix or used with additives as a filler, so I'm not intimately familiar with it in a woodworking environment.  However, the basic chemistry is the same.

Once it's on, it's probably not coming off without damaging the workpiece or going through miles of sandpaper (and ending up with an uneven surface afterward).  You will probably have only one good shot at it.  Like Peter mentioned, it's a high-build material that you will either need to keep out of driver holes and rabbets or be prepared to accurately mill those surfaces afterward with corresponding wear on those tools.  You could coat those surfaces with a mold release and chip off the epoxy afterward, but those are generally water soluble substances and couldn't be applied directly to MDF without it swelling, so they would need to be well primed beforehand, and you would still need to figure out how to keep the edges nice and clean.  Damming the edges with tape like the video showed (before he wisely pulled them off), could keep surfaces dry, but it will create a high spot and dull surface against the tape so I don't recommend that approach.

All that is ignoring the environmental and handling factors.  Epoxy is highly susceptible to ambient air temperature, while at the same time it will create it's own exothermic reaction which can get away from you.  I assume that epoxies meant for woodworking are far less prone to runaway reactions than what I'm used to, but it's a fact of all epoxies that the reaction creates heat which will in turn speed up the curing process.  Read the instructions carefully and stay within the temperature, humidity and working time recommended by the manufacturer.  If you can't control these things, you might look at another option.

Practice, practice, practice on test pieces to make sure you understand how it's going to act on the material and what the outcome will be.  Once you start pouring on the workpiece, you are committed.

Finally, if you thing MDF dust is bad, epoxy dust is horrible.  It's superfine and won't break down.  At the very least wear a well-fitted N95 if you need to sand.

Epoxy is great stuff, but it can be humbling. 

[rtate]

Sounds like the Risk to reward factor is too great for me.   
Back to regular paint I guess...   

[Mark Korda]

Hi Edgar, I'm a painter. The only time I need to prime with oil is when there is a surface that can rust. Also to contain nicotine or things like knot resin that bleeds right thru (latex) primer. I don't think you have to worry about that. If your MDF is real smooth or shiny you have to rough it up with some 150 grit sand paper, little microscopic scratches for the best adhesion and you should be fine with a latex primer. Get a little hot dog roller and your set....Mark.....the little hot dog roller with a napped end gets in the cracks too.

[JWCoffman]

The primary advantages of epoxy (toughness, shatter resistance, stability) aren't really necessary with an MDF speaker baffle surface unless you plan on throwing sharp objects at them.  There are far more color and effect options with paint than with epoxy, especially when you start considering auto paints.
The best part for me would be that a screw-up with paint wouldn't be the end of the world.

[jules]

Has anyone ever tried epoxy resin type finish ?
Something like this :

Basically, extreme overkill!

[Edgar77]

That might be the key question here. If you're aiming for a mirror finish, you'll be doing much more work than something less revealing [to use a favoured audiophile term  ]

I just saw this video about painting: https://youtu.be/o_1IPQJsu5E

Peter Millard seems to know what he is talking about. And he also talks about the big difference about shiny finish. Summary: Don't even try if you don't know exactly what you are doing.

[Peter J]

I just saw this video about painting: https://youtu.be/o_1IPQJsu5E

Peter Millard seems to know what he is talking about. And he also talks about the big difference about shiny finish. Summary: Don't even try if you don't know exactly what you are doing.

I've encountered him before on YouTube. Seems thoughtful and well spoken and, as his video suggests, honest. One thing worth noting is that fine pigmented (paint) finishes are often more demanding that that of exposed wood grain. Many ways to get to a reasonable finish on wood grain with hand finishing techniques, less so with heavily pigmented smooth finishes.

In contrast to what many think, the finishing stage on a lot of woodworking is the lion's share of total time, and sometimes money, spent on project. It is a discipline and skill set in and of itself.

If a "piano" finish is the desired result, the automotive world is where I'd turn. Prime, fill, sand, seal, color, clear, cut and polish. But it's outside the manufacturer's  recommended procedures because it's on wood, so knowing something about the way products interact is helpful. It's also interesting to me that in the furniture world, high gloss finishes are passé right now. Yet in the speaker world, high gloss still seems to be the holy grail.

[Mark Korda]

(https://www.wholesalemarine.com/pettit-easypoxy-high-gloss-topside-marine-paint-82251.html )   Edgar, every year a friend of mine and I paint his lobster boat. When we paint the hull,above the waterline, we use Petit Easypoxy. It's costly but easy as pie to use. For your speakers you might have to use an oil based primer. We only need 1 coat but a new speaker would require at least 2 coats. i don't know where you live but most boating stores or marinas carry Petit paint. The result, with a short napped mini roller, wiener or hot dog rollers, comes out like a shiny ,new, black grand piano even though they have a multitude of different colors...Mark Korda

[Peter J]

(https://www.wholesalemarine.com/pettit-easypoxy-high-gloss-topside-marine-paint-82251.html )   Edgar, every year a friend of mine and I paint his lobster boat. When we paint the hull,above the waterline, we use Petit Easypoxy. It's costly but easy as pie to use. For your speakers you might have to use an oil based primer. We only need 1 coat but a new speaker would require at least 2 coats. i don't know where you live but most boating stores or marinas carry Petit paint. The result, with a short napped mini roller, wiener or hot dog rollers, comes out like a shiny ,new, black grand piano even though they have a multitude of different colors...Mark Korda

Respectfully Mark, it should be pointed out that EasyPoxy is not an epoxy paint, although the name would suggest it. It is simply a high quality, air drying, polyurethane finish that, without flatting compounds, dries to a high gloss. Even with great flow out characteristics, no roller applied finish will achieve "piano" qualities. In my mind that term implies a glass smooth, dead flat, glossy finish.  "Piano black" as I've seen it applied in the audio world, seems like more of an appropriated term to lend cachet for either marketing or ego. At least in my  book, glossy black is just that... glossy and black. There's lots more to that, but I'll leave it there.