How Best to seal MDF


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Old 12-28-05, 10:30 PM
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How Best to seal MDF

Recently, Ive learned that MDF is made with urea-formaldehyde which off-gases. Apparently, many people are concerned about this.

I know there are formaldehyde free MDFs but it is very inconvenient for me to get.

I have a post under the "Lumber/Siding" section at this site about how much of a concern this really is, but I have a different question here...

If I plan on using this for moldings, can I paint the MDF on all sides to lock in any gases? Would priming be better? I looked at the BIN primer and they have a shellac based primer. Shellac, as I understand, is an excellent sealer.

Will sealing MDF do anthying? If so, is paint enough? Or is primer needed? Latex or oil based? What about plain shellac? Obviously Im not sure. Any thoughts out there?
 
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Old 12-29-05, 06:31 AM
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Personally I believe the concerns about mdf gasses are overblown, although I am aware that some are affected by minute amounts of different things.

Priming and painting mdf with a solvent based paint should seal the mdf.
 
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Old 12-29-05, 10:36 AM
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I would second the motion for BIN.
 
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Old 12-29-05, 04:13 PM
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Marksr, my gut tells me its overblown too. I mean, there is formaldehyde (the gas in question) in plywood, all pressed products, mattresses, carpets, insulation,etc. Not to mention all of the other things that are in our water, food, and floating around our air.

BUT... my paranoia has gotten the best of me.

When you say to paint with a "solvent" based , what does that mean? Shellac and not latex primer?
 
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Old 12-29-05, 04:35 PM
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Solvent means oil or shellac. They seal better than latex. I'm no chemist but seems like I heard that the molecules in solvent based paints are closer together than with latex.
 
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Old 12-29-05, 04:48 PM
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Sealing it with BIN (shellac-based) is the best way I know to seal it
Oil-based sealer would be #2
Both are solvent-based (not water-based like latex) and would seal better than latex sealer
 
 

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