# Polyurethane finish on MDF



## lindsayswoodwork

Is it ok to use polyurethane finish on MDF? I used a 3/4" sheet of MDF as the very top of my work table I just built. Thanks!


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## Dave (PacNW)

*Go For It!!*

Be sure to use Oil based Poly! Water based will cause the surface to swell.( WATER+MDF= BAD NEWS!:furious

Dave(PacNW)


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## lindsayswoodwork

Dave (PacNW) said:


> Be sure to use Oil based Poly! Water based will cause the surface to swell.( WATER+MDF= BAD NEWS!:furious
> 
> Dave(PacNW)


 
I figured that. Thanks! :thumbsup:


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## RLHERRON

That's what I did and it works fine. I did all my tops that way. One thing I would probably have and will do different, on my main work bench that cathes all the messy work (paint, stain, etc.) I'm going to purchase and in-expensive piece of 4x8 hardboard for that area. 

Had a couple of roof leaks  on the MDF and the poly worked great.

RLH :thumbsup:


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## lindsayswoodwork

Will, so far I have 3 coats of Polyurethane and it just turns the MDF to a brownish color but unable to have a high gloss. What am I doing wrong here? If there a primer I should have used to seal the MDF with? If I paint it then apply the poly will that leav a high gloss finish? Thanks!


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## JW_in_Indy

lindsayswoodwork said:


> Will, so far I have 3 coats of Polyurethane and it just turns the MDF to a brownish color but unable to have a high gloss. What am I doing wrong here? If there a primer I should have used to seal the MDF with? If I paint it then apply the poly will that leav a high gloss finish? Thanks!


What "color" did you expect the MDF to be once finished? Always test your project first on either scrap or back side prior to starting the entire project. A very easy way to "see" what an oil based finish will do is wipe your project with mineral spirits (which you probably should have done to give it a final cleaning prior to finishing anyway).

As for sealing first.... you could have used a sanding sealer or even better, some dewaxed shellac prior to using the poly. But honestly, I'm not sure exactly what you are trying to achieve here. All we really know for sure is you are wanting to apply a finish to a work table top. Nothing about a desired "color" or gloss or no gloss, finish build desired etc.


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## lindsayswoodwork

The color is fine. I just want a glossy durable finish on it. I figure I’ll need a couple more coats. Next time I’ll use a sealer so I don’t have to apply so many coats of poly. :icon_smile:


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## JW_in_Indy

lindsayswoodwork said:


> The color is fine. I just want a glossy durable finish on it. I figure I’ll need a couple more coats. Next time I’ll use a sealer so I don’t have to apply so many coats of poly. :icon_smile:


Maybe an epoxy type finish or possibly one of the table top clear's might have been a better choice if you were looking for something super glossy. The poly finish should be fairly durable but will continue to soak into the MDF quite a bit I think. Keep at it though and eventually you'll get a nice build. I'd caution you to stay patient though and let each coat dry thoroughly before applying the next coat.


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## wletson

are you sanding or 00 steel wooling between coats? Don't see why you wouldn't get a glossy finish.


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## lindsayswoodwork

wletson said:


> are you sanding or 00 steel wooling between coats? Don't see why you wouldn't get a glossy finish.


 
The MDF was just sucking up the Poly since I did not apply any sealer before hand. :huh: I'm going to applying a 2nd coat of oil based red paint today and it's looking great!. Will have pics in a few days.


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