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Working with MDF

I'm working on a new build using an MDF flat pack from PE. Since I normally use plywood, I'm wondering what additional steps - if any - need to be taken before painting or veneering MDF. I vaguely remember reading something on PETT waaayyy back in the day about sealing MDF with glue, but don't remember if it was for a special circumstance or a general best practice and have been unable to relocate the thread.

If anyone can help out it'd be greatly appreciated.

Comments

  • If your going to veneer it no sealer of any sort should be used. I do recommend using red titebond and a iron to put on the veneer. As far as painting MDF if your going to use cheaper grades of paint then use a sanding sealer so paint won’t soak in as much. My .02
  • For veneer work I seal MDF with glue for iron-on and vacuum bag.  I'm using yellow glue for veneer with paper backed.  For painting I use Bin 3 shellac based and spray.  I've sealed some of the inside of Synergy horn and it seems to have helped with joint movement.
     John H, btw forum has decided I don't get emails
  • I've long been a proponent of sealing with straight undiluted Elmer's white glue. Just use a brush and coat it. If you want Duratex, then don't bother. If you want paint, then I highly recommend sealing it at least somehow.
  • Thanks for the responses guys.

    Based on the general consensus, I'll seal before painting. Hopefully the weather cooperates long enough to get these done before Iowa.
  • Before Iowa obviously didn't happen.

    I wound up experimenting with a non-traditional method. Early results are promising with the first paint session today. I'm going to wait a few days and if nothing untoward has happened to the cabinet I'll post up what I used and the reasoning for it as well as some pictures.
  • Well, I'm going to consider the Dullcote experiment a success. I wound up choosing this method through a multi-disciplinary logic train and am pleased with the results so far.

    I started out with the knowledge from model building that dullcote will seal cardboard so it can be painted without deforming. Through a conversation with a fellow model builder who practiced his craft professionally in his younger years I learned that MDF is a type of cardboard. This lead to an "I wonder if ..." moment and I decided to test it out to verify the hypothesis.

    This is the baffle sealed with glue (with an overspray of Dullcote because of slightly uneven coverage).


    Probably could have used a little sanding and another coat of paint after, but otherwise not too bad.

    Here's a side panel sealed with Dullcote only.


    Other than needing to go a little heavier on the edges, I'll buy that. Nice and buttery smooth - no sanding required.

    After this experiment, Dullcote is my go-to sealer when working with MDF.
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