Painting MDF - FloridaSPL
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Old 04-20-2011, 11:11 PM   #1
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Default Painting MDF

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/prodde...?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....













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Old 04-20-2011, 11:12 PM   #2
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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.
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Old 04-20-2011, 11:16 PM   #3
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There are and will be arguments that you should resin the wood first to keep it from soaking up the primers and paints. Negative.
Your just making more work for yourself. A 2k primer will soak in a small amount yes, but it will cure and lock in and stop any further soaking and all you to continue to block the surface flat.
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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Old 04-20-2011, 11:18 PM   #4
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And I am done with that one.

I posted this here cause I gather that you guys (admins) need to approve these and then move them to the Knowledge Base section.

So here you go. Approve away and then move. Appreciate it.

BTW..... this is 100% completely written by me, pics by me, work by me.
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Old 04-23-2011, 10:09 AM   #5
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You ask... I make...you ignore?
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