MDF Finish

[bjackson]

I've finished one of my enclosures pretty much, but it's pretty umm...crappy looking. Lot's of dried glue, screw holes, etc. (The screw holes are countersinked atleast). (The dried glue was brushed off before drying so it's just stained now).

I need to finish it to look decent. I really don't have a preference at this point. I was thinking maybe using bondo, or woodfiller to fix it. Or maybe using woodfiller, and sanding everything and putting a thin piece of nicer wood on top, but I was worried about diffraction off the front baflle if it was no longer flush.

ANY and ALL suggestions welcomed and appriciated. I have one week before I start working on them again (damn college, taking all of my time away from my precious audio equipment)

[bjackson]

BTW, the box is 48(H)" x 18" x 18" outside dimensions. My budget is limited, but I'd rather wait and have quality than do something that is cheap and crappy.

[ultrachrome]

I don't know if what you fill the voids with is that critical. I'd just go with whatever your hardware store recommends.

So I take it you flush-mounted the drivers on the baffle? If you were going to veneer, I think you'd usually cut the driver holes after you veneered it as it is difficult to trim the veneer around the driver holes recesses.

If you want the wood look, you could veneer the sides, and then slap a second layer of real wood on the baffle and recut the driver holes in the same locations. Then round over or bevel the edges of the baffle.



I've also used spray-on aerosol bedliner which looks really good but for a speaker that size, I'd save it for just the top sides and front as it can get pricey. Use whatever you want on the back. Unlike what you might think, the rough texture does not really hide surface flaws so if you go this route, smooth your surfaces well. A good palm sander makes easy work of this.

[audio-kraut]

Filling, sanding, filling, sanding;
priiming, sanding # 220
filling whats now visible;
sanding, # 220 or above;
priming and sanding # 220

first coat paint, varathane colours in plastic;
sanding # 400
second coat, same paint, sanding # 400
thirs coat.

Between each sanding and coating wipe with tack cloth.
Gives you piano paint like finish. I had coated mine five times with finish paint. Looked excellent - and that night my shop burned down

The truckbed liner can look great - but some prep is needed. You have limited time to work it, as it is epoxy based and contains a hardener. Should only be used in well ventilated areas - i.e. out doors.

[rcavictim]

Just a word of caution about the Varathane Colors in plastic. I have been using white shellac diluted with alcohol to seal all my MDF projects prior to applying paint. The varathane says not to use shellac as an under sealer. I guess it won't stick.

[richie00boy]

With MDF is important to seal or use the correct primer. MDF soaks up paint. I use proper MDF primer, but you can seal first with a 50/50 water/PVA mix to seal, then prime with normal wood primer. However make sure you fill any nicks or screwheads beforehand. Just use car body filler, but you can get dedicated wood filler that mixes up the same way.

Get your finish as good as possible before any priming, then sand between each 2-3 coats with 800 grit wet and dry paper to get a nicer finish. Do that a couple of times and your ready for topcoat.

[Paradise_Ice]

Another thing you could do after you have smoothed the exterior off, you could cover it in a textile fabric, there are so many to choose from these days, i have a wee hobby and its covering everything in a sued velour type grey a few cans of spray glue which has amazing strength and it will hold almost anything down.

This give a nice matted finish if done well, so pratice is the key.

This can give a very nice tactile finish that everybody wants to touch and rub their hands against all so its very cheap to do.

Adding a vaneer is good to but its very time consuming and can be costly depending on the vaneer quality and type.

i think maybe its the PVA i use but mixing it 50/50 with water makes its to weak to seal MDF.

Using the car body filler is also an excellent method but also takes time and skill.

[Cal Weldon]

If you like a texture coat, this is what I used for the selenium coax boxes. It's "Accents" by Rust-Oleum. This is the "Stone Creations", black granite. Each can did 15 square feet or one can per cabinet in this case.

[Cal Weldon]

This is the completed box

[dhenryp]

One "trick" to finishing MDF is to seal any exposed edges. It is very absorbant otherwise and will soak up many many layers of paint. I take some ordinary yellow carpenters glue (take your choice, I often use Titebond) and dilute it with water ~ 50%. Put this on the edges before doing any other filling or priming.

I've had good luck with Bondo - easy to sand and dries very quickly. The first coat will sometime shrink and require a second coat for a smooth, flat finsh.

If you have the patience and stamina you can get an excellent gloss finish with plain old Rustoleum Spray Lacquer. As Audio-Kruat said, be prepared to do quite a bit of sanding. Spray on textured paint still needs good prep but the actual painting will go much quicker.