MDF releasing urea formaldehyde?

[mikem]

I've read bare MDF slowly releases urea formaldehyde. Is this true and if so what is a good sealer for the MDF box before I paint it? I have read linseed oil and yellow glue/water mix.
TIA

[nate]

I have tried painting MDF many times and the only way to get a seam free finish and keep it that way is to coat the entire box in some sort of epoxy resin (gel coat). Brush the gel coat over the entire box, sand with 220 330 400 grit paper. Prime with a high build automotive primer sand with 500 then 600 grit. After all this, the box will be ready to paint. I have included a link for a good cheap resin.

<A HREF="http://www.jamestowndistributors.com...milyName=White">http://www.jamestowndistributors.com...milyName=White</A>+and+Neutral+Gelcoats

[bobbarkto]

Yes, almost all panels use resin or glue that contains formaldehyde. This includes most plywood. Particle board is probably the worst as the glue/resin content is very high.

Medite brand MDF panels are formaldehyde free.

Oil finishes or glue as a sealer will not block the release. Oil won't even slow it down. Don't know about glue.

As Paint Guy mentioned, epoxy encapsulation will stop it, as well as giving you a good moisture barrier that will keep joint telegraphing to the bare minimum.

Epoxy is an excellent sealer/primer too.

> I've read bare MDF slowly releases urea
> formaldehyde. Is this true and if so what is
> a good sealer for the MDF box before I paint
> it? I have read linseed oil and yellow
> glue/water mix.
> TIA

[Mr.Thomas Aaron Hero]

> I've read bare MDF slowly releases urea
> formaldehyde. Is this true and if so what is
> a good sealer for the MDF box before I paint
> it? I have read linseed oil and yellow
> glue/water mix.
> TIA
I wouldnt worry about it,You will breath in more toxins just driving down the freeway for five minutes than you will from MDF or plywood.

A.H.

[Dirk]

Indeed. Nobody's sued the cabinetry industry, and they place MDF in close proximity to our cookware.

> Yes, almost all panels use resin or glue
> that contains formaldehyde. This includes
> most plywood. Particle board is probably the
> worst as the glue/resin content is very
> high.

> Medite brand MDF panels are formaldehyde
> free.

> Oil finishes or glue as a sealer will not
> block the release. Oil won't even slow it
> down. Don't know about glue.

> As Paint Guy mentioned, epoxy encapsulation
> will stop it, as well as giving you a good
> moisture barrier that will keep joint
> telegraphing to the bare minimum.

> Epoxy is an excellent sealer/primer too.

[bking]

The flat portions will take two or three coats with a light sanding between coats. Any exposed cut ends will take a couple more. I'd cut the shellac 50/50 with denatured alcohol for the first couple of coats, then go full strength on the final one. Shellac dries pretty fast so you should be able to apply the whole schmere in a day. The nice thing about shellac is you can paint it with just about any solvent-based paint. I wouldn't recommend water-based paint like latex because shellac doesn't like water (or alcohol for that matter). Zinsser is a good brand of shellac that's available just about everywhere.

[mikem]

What about polyurathane? I guess I picture in my mind in the end a smooth paint job that would cover any edges so it looks like one box not too shiney of a gloss. Of course I might just use the veneer.

[bobbarkto]

Shellac will seal well enough for paint, but it won't help prevent moisture problems on down the line.

A few coats of any high build finish will slow off gassing enough so that all but the most sensitive among us won't experience any problems.

However, if you feel any exposure is too much, then switch to a different material as you'll never completely eliminate off gassing with any finish.

> What about polyurathane? I guess I picture
> in my mind in the end a smooth paint job
> that would cover any edges so it looks like
> one box not too shiney of a gloss. Of course
> I might just use the veneer.

[bking]

...you shouldn't be using MDF to begin with!

[mikem]

> ...you shouldn't be using MDF to begin with!

oh I was just reading some woodworking forum and they were against the stuff and said it was dangerous. I never heard of fumes from MDF but knew it is the product of choice around here. If there is problems, I am way into being exposed beyond help by now. I cut a lot to try different stuff but never finshed it before. That's the next chapter in my DIY story.

[bking]

Yeah, I cut a ton of the stuff too. I wear a dust mask most of the time and I also have a 1 micron dust control rig in my shop. As Aaron mentioned earlier, the amount of formaldehyde out gassing from the MDF is pretty minimal to begin with.

[bobbarkto]

Considering only sheet goods commonly used to make loudspeaker enclosures I'd rate it as moderate.

Whether it's a health concern or not, it depends on the individual to a large extent. Some people are very sensitive to it. Others become sensitized after prolonged exposure.

[bobbarkto]

Not really.
Just the changes in RH can lead to joints noticeably appearing or telegraphing through a high gloss finish.

Plywood isn't immune to that either. But it's generally more controllable/less of a problem.

> ...you shouldn't be using MDF to begin with!

[bking]

Two ways to cope with the joints telegraphing through the finish. Number one is use 45 degree joints instead of **** joints. And number two is seal the hell out of the **** joints with shellac. I've gotten very nice black piano gloss finishes using both techniques.