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Whats the best way to paint MDF? Get a nice shinny finish on it, something that I can show off. Any special techniques? combination of sanding/priming... LEND ME YOUR KNOWLEDGE.
 

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sand it smooth resin it sand it and then paint it with car paint for the best finish
 

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your going to want to use 300 grit for sanding the resin
 

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what kind of resin? I have super limited experience in box building, and almost nill in painting.
 

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this is my box resined
 

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its like glass
 

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for strength yes but is the glass mat needed not imo enless it is going to have crazy amounts of power and needs the strengh
 

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If your wanting to have the exterior of an MDF enclosure finished in shiney paint, you do not have to resin it. Thats a waste of money and time.

I am about to head off to a show, but when I come back I can do a nice write up with links and pics if you like.
 

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guys..

I've done the work to bondo prime and paint MDF. It's a b1tch and takes a shit load of work. which is why I said to Resin it.

resin sets and can be sanded primered and painted in the same day.

but... if you have a week to devote to it and are ok with it turning out {just ok} after all that work, go ahead.

I am surprised the "glassman" EpicenterDesigns said that you didn't need to. just plain surprised.{shaking head amazed}


If you do use resin, it's easiest applied with a low-nap roller on smooth surfaces.

good luck
 

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Here are the products you should have.....
Sanding blocks. The longer the better. I prefer Dura-Blocks.....
http://dura-block.com/durablockline.html
Having the 6 piece kits handy are great.

Next, you need an assortment of PSA sandpapers for the blocks. I suggest 80, 180, 220, 320 and 400.
http://www.abrasivesoasis.com/proddetail.asp?prod=sg236xxx

Next, you will needs some good filler primer. I use and live by Evercoat Slick Sand or Feather Fill.
http://www.evercoat.com/productDetail.aspx?pID=28 SLICK SAND
http://www.evercoat.com/productDetail.aspx?pID=171 FEATHER FILL
You do need a gun that shoots with a 2.0 tip or bigger.

You also need a quality bodyfiller and I suggest rounding over all the corners with a router for cosmetic purposes. Also a can or 2 of flat black rattle can paint for a guide coat. The cheap 99cent cans from Lowes works great.


Use bodyfiller to fill in any holes left by screws or brad nails. Also use it to fill in seams from the wood joints.

As flat as MDF looks, it is quite wavy. So you should lightly mist some of the black paint over the surface, then use some 80 grit paper and the sanding block and sand till the paint is all gone.
Mist paint again. Repeat sanding block action with the 180 grit.
Now blow all the dust off the box and shoot 2 - 3 coats of the primer on. Thick. You want this as thick as you can without making mountains with the runs.
Let that cure for as long as you can. MDF will soak up paints, and primer is no different. But it won't soak up alot of the 2k primer due to it being so think and it having a catalyst to cure it.

Once again, mist the black paint over and start doing a rough sanding with the 180 grit if the primer has alot of runs in it. If it is pretty flat, start with the 220 grit. Sand till almost all the black is gone.
Mist again and sand with the 320 grit. Once done with that, mist again and do the sanding with the 400 grit.

Seems like alot of sanding, but the prep makes the paint. Paint exaggerates flaws, doesn't hide them.
The black paint (guide coat) doesn't lie. If it is gone in the sanding process, the primer is flat.
Clean and prep for the top coat.
Then lay on plenty of clear. Wet sand and buff as needed. This can also be done perfectly fine with a single stage paint.


Do not be lazy and use air or power tools for the sanding process. They will leave low spots that will pop out and slap you in the face once painted and you will be pissed.


Here is a box I did with MDF sides and I used this exact same method. Painted it black and it looked like a perfect piano finish.





This is after pimer and with a red guide coat.....





Guide coat sanded down. As you can see, I went thru the primer to the wood. Spray more primer so you can level it all out.







Once done, you can spray the color. Here is the box drying. While it can be called done now, some will want an even flatter, shiney finish.








Wet sanding the clear coats....





This is 3000 grit wet sand before buffing....






And the buffing. In the 2nd pic, you can see the difference in the top compared to the sides (unbuffed)....







All buffed out and ready to install....














I apologize for the poor picture quality. These are some old pics.

And this probally should have been it's own thread or something. Sorry. Maybe some mod can do that?
 

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Now let me explain why I say resining the MDF is more work than is needed.

In my last post, I mentioned that MDF is not as flat as it looks. Add resin on top of that and you have non flat resined MDF that still needs to be blocked flat.
Resin is a much harder surface than raw MDF and will take more work to level out, While doing so, you may sand thru the resin to the MDF anyways.
So basically, your pouring money on the MDF just to sand it off.


Now if you want to make the box water proof, then resin it. BUT, only resin it after you have blocked the MDF flat and then coat it in an epoxy resin. Not a polyester resin.
Poly resin is still more pourous than epoxy and will eventually allow moisture in.
 
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