A good paint finish for mdf?

Discussion in 'Carpenters' Talk' started by UNDER-FLOOR INSULATION, Mar 7, 2006.

  1. Hiya folks
    I'm making my own radiator covers out of mdf. How do i prep them for painting and end up with that smooth factory sheen the overpriced ones from the diy stores have?
    Many thanks.
    Toffeeboy.
     
  2. handyman.

    handyman. New Member

    its the routered edges that 'fur' when you put the mdf primer paint on it. What you do is prime, lightly sand to remove the fur, and prime again.

    After that, you really need to spray it to get a super smooth finish, as thats what the factory ones are finished with.

    I would use a good satinwood (dulux trade satinwood), with a good brush (purdy)............as i dont have a sprayer;)
     
  3. Thanks for that fella. I'm using a cheapo router at the mo so many furry edges! I just want them to look good enough so 'er in doors dont bang on about how " you should of just bought them from B&Q like i told ya and saved all that time and money
     
  4. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    You can achieve it with spray paint only, but it ain't easy for a novice.

    Firstly you have to make sure it's ready(rubbed down, as smooth as possible.

    Then you need a primer coat of spray paint, - well, 5 or 6 really. Sounds a lot, but it's not.

    First coat, lightly sprayed on all over, a good 12" away, hardly applying any paint at all. Second coat the same, and a third(should be able to apply each coat after a couple of minutes).

    Then, 2 more coats, gradually increasing the amount you put on each time, and now about 9" away. Now you can give it a slight rub down if necessary.

    One more coat. Then a top coat(if same colour as primer)or two if different. As thick as you can without running.

    It's finished. Obviously, the thicker you put paint on, the longer you have to leave between coats, but these will only be the last couple of coats(say 15mins tops).

    Sounds like a lot of work but it isn't as long as it sounds. Remember, more thin coats are better than less thick coats. Good luck.






    Mr. HandyAndy - really
     
  5. handyman.

    handyman. New Member

  6. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    only learned about this a short time ago here
    http://www.trustedtradesmen.com/forum/forumposts.asp?
    TID=2084&KW=fur&TPN=1

    Handyandy, the fur will appear after first coat,
    which you will need to rub down. Well, i think you
    would, but have never sprayed mdf



    The idea is, with the first coat especially, that the coat is so fine, that it is almost dry as it hits the mdf, so it helps to NOT bring the fur up. Same with the second coat. After that, a wet coat is not going to bother the mdf because it has been sealed, with almost dry paint.




    Mr. HandyAndy - really
     
  7. Scrit*

    Scrit* New Member

    I'd suggest that you sand the edges to about 120 grit then treat them with MDF sealant (any good paint supplier will sell you a water-based acrylic MDF sealant). This will rasie the grain, so you will have to flat back with 120 to 180 grit and reseal, possbily up to 3 or 4 coats depending on how much grain raising you get. I'd suggest giving the flat surface two coats cut back in the same way. After that one coat of undercoat then one or two coats of top coat to finish. Denib between coats with a Scotchbrite denibbing pad (even Machine Mart sell them). Yes, spraying is the best way, but a perfectly good result can be had if you spend the time to seal before you prime, denib between coats and use more thin coats than less thick ones.

    Scrit
     
    TheJay likes this.
  8. dunc

    dunc New Member

    I do a lot of matching up work. So I allow for plenty of room around the construction for lots of paint. So after using mdf primer, I whack on lots of thick primer and sans and recoat etc. Whe it comes to the final coat it starts to match up nicely with the originals, which are usually overpainted anyway.
     
  9. goldenboy

    goldenboy Super Member

    i was a sprayer for a few years on mdf one of the main things is to never touch it with aluminium oxide paper as even 240 or higher will leave scratches, use silicon carbide grey flour paper instead do all your filling with davids car filler the old stuff with a picture of an austin maestro on the outside (honestly). light to medium coats of primer is best. rub down between coats with a fine 3m pad and just keep piling on the primer until you have achieved a finish that you would be happy to have as a topcoat because the topcoat will just follow the primer and show up any imperfections. couple of coats will sort it. also you can seal all the sawn and routed edges before you start with a clear cellulose basecoat and rub them down if you are having problems with dodgy edges, just do a sample first to check that it doesnt react with your paint
     
    TheJay likes this.

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