Sealing MDF kitchen shelf

Discussion in 'Decorating and Painting' started by bullethead123, 20 Jul 2021.

  1. bullethead123

    bullethead123

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    Hi all,
    An MDF shelf has been fitted just above a kitchen sink and some damage has occurred - see photo. I guess the best remedy would be to replace the MDF shelf with a wooden one, but could an effective repair be made with some kind of sealant? Maybe some of that sticky back plastic?
    What do you all think?
    Chris





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  2. opps

    opps

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    I suspect that it may have been painted with waterbased paint, and further, that it wasn't moisture resistant MDF. Oil based paints would be more durable but even oil based paint over moisture resistant paint won't be happy with regular standing water. That said, nor would a painted hardwood shelf.

    You can definitely "repair" the damage. You can paint over the raised bits with primer, let it dry and than sand it flat, you will invariably end up sanding through the surrounding paint though, which will need re-priming, and then sanding flat (again). Then once confident that it is flat, undercoat and top coat. As a decorator, if I were already on site and asked, I would probably estimate about 2.5 hours to repeair/repaint it, but the final finish would hopefully be better than the existing finish- those window boards are typically pre-primed. Most decorators don't bother sanding them completely flat (and to be fair, most customers wouldn't notice the difference unless you show them the difference in finish)

    If you want a pretty much maintenance free shelf, consider replacing it with stone/stone resin.

    Off hand I can not think of a "wrap" finish that would be easy to apply and durable.
     
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  4. bullethead123

    bullethead123

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    Thanks for your input Opps.
    Primer eh? I thought undercoat was primer:). Is this the kind of stuff you mean? it calls itself an oil based primer but it seems very expensive.
    Would it be worth sanding down, giving it 2 or 3 coats of Zinnser and then (oil-based) undercoat and gloss?
     
  5. opps

    opps

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    Water based primers double up as an undercoat (on the second coat).

    You linked to Zinsser BIN. It is a pigmented shellac suspended in alcohol. I use it for stain blocking. It isn't oil based, it is alcohol based. If you only intend to use it it to "prime" the raised MDF, it will be overkill. There is no reason why you can't use waterbased primer/undercoat or even oil based primer (if you have some).

    I would spot prime the raised areas, let the paint dry, sand it back. Prime again, and then sand back (because the MDF "grain" will have raised). If you want to stick with the existing MDF window board, I would recommend 2 or three coats of oil based eggshell paint. Oil based eggshell will adhere to the existing surface (once you sand it to provide a key). If you want to use gloss then use either a waterbased undercoat or an oil based undercoat before applying the oil based gloss.

    Oil based eggshell is far more forgiving than oil based gloss. It is easier to work with and specks of dust are far less noticeable.
     
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  7. bullethead123

    bullethead123

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    Thanks for the advice Opps.
    I got some Zinsser and gave the whole shelf 3 coats followed by a coat of oil-based undercoat. Looks a lot better even now. I'll apply a couple of coats of this Eggshell paint. It's the paint I habitually use and seems to give the best results. I didn't (until now) realise why.
    :D
     
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