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Deep glossy finish for MDF?

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Forum topic by Propaganda posted 07-22-2010 07:50 AM 3788 views 0 times favorited 5 replies Add to Favorites Watch
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Propaganda

4 posts in 1537 days


07-22-2010 07:50 AM

Topic tags/keywords: mdf finishing painting mdf question

Hi

We are having a rough time with this, we are trying to figure out how to finish MDF shapes. (stars, butterflies, etc.) The end goal is a nice deep glossy surface (in black). These items will be hung on interior walls and rarely handled.

Using Rust-o-leum crystal clear enamel (rattle can!) over vaspar flat black spray paint yielded the look we want. However the many coats and sanding took way too much time. BTW, does anyone know if that rustoleum stuff is the same a their clear enamel which is branded not the same as the rattle can stuff? I ask because we are now using HVLP and using rattle cans is laughable and expensive.

So we tested vaspar latex enamel paint with vaspar polyacrylic clear coat. It came out just ok. Not much of a shine and no depth. Next up is BenMoore IronClad Latex with their Stays Clear top coat. I don’t foresee a great improvement, but hey at more than twice the price I still am hoping. Also I will be using kilz as a primer to lessen raised fibers.

Now I am contemplating trying an oil-based paint with some sort of clear coat. Any suggestions on the clear coat?

Naturally time is a huge factor and we would like to find a balance between time and outcome. We can really use some experienced direction.

Thx

-- "Gentlemen, you can't fight in here this is the war room!"


5 replies so far

View vicrider's profile

vicrider

178 posts in 1564 days


#1 posted 07-22-2010 08:09 AM

You’re dealing with one of the reasons MDF isn’t chosen much as a finish material. the internal area is not as hard as the surface and thus eats finish for breakfast. My advice is to start out with a few coats of shellac (don’t bother mixing your own). Just buy a quart of Zinzer ‘Bulls Eye’ and a quart of ethyl alcohol (should be about $20.

It’s clear and fairly thin so it is easy to apply. You can brush it on quite easily. I’ve heard it’s pretty warm in VA right now so they should dry fairly quick.

Then a quick sand and tack and start your finish coats.

vicrider

-- vicrider

View 559dustdesigns's profile

559dustdesigns

632 posts in 1833 days


#2 posted 07-22-2010 12:01 PM

What about black lacquer paint than a sanding sealer with glossy clear lacquer over that. Make sure to shoot it early before its too hot outside.

I recently read a tip on the wood magazine site about sealing the edges of mdf for finishing. It said use 1to1 mix of white glue with water. You brush it on the edges and let the project dry before sanding, may also require multiple coats. I want to try this.

For past work I installed car stereo we used mdf for our enclosures for subwoofers. Sometimes we painted the inside of the box and filled in detailed areas with bondo filler used for auto body. This worked well but some times the filler cracked or you could actually see where the fill was applied. The only way we could prevent this was to skim coat the entire piece. I’ve seen on tv that this is a common practice on custom cars before expensive paint jobs. We also used sandable primer the cheap stuff from Auto Zone in a rattle can over the Mdf. Hope this is slightly helpful.

-- Aaron - central California "If you haven't got the time to do it right, when will you find the time to do it over?"

View Rick  Dennington's profile

Rick Dennington

3443 posts in 1859 days


#3 posted 07-22-2010 04:07 PM

Greetings,

My question is: Why are you using MDF instead of something like pine that’s gonna be painted anyway?

I really don’t think there are any fibers in MDF. Afterall, it’s just compressed paper… good for jigs and fixtures

-- " I started with nothing, and I've still got most of it left".......

View Nomad62's profile

Nomad62

716 posts in 1623 days


#4 posted 07-22-2010 05:39 PM

Consider using an epoxy type finish, it’s thick and shows depth wonderfully. I haven’t seen someone use mdf like you are before, I’m interested in your outcome. Good luck!

-- Power tools put us ahead of the monkeys

View Propaganda's profile

Propaganda

4 posts in 1537 days


#5 posted 07-22-2010 09:59 PM

Yep, it’ been about 100F during the day for the last few weeks, and my shop is temporally setup in my back porch with no air treatment.

You guys gave me lost to think about. Even though I wanted to stay water-borne if using black lacquer paint works better I will switch over.

When it comes to the edges I tried shellac, water/glue, poly, plasticdip, casting epoxy, drywall mud, wood filler, Kilz, hand rubbed enamel, and cat pee. Well, ok, not the last one. Anyone one of them takes 2 to 3 coats with massive sanding in between and non of them really work better than the others but the timing and sanding pressure needed varies. Next item I will be using kilz as a edge sealer and topcoat sealer along with other techniques you guys presented.

Nomad62, do you have any suggestions for a epoxy type finish? In my area we have Sherwin Williams, Ben Moore, and the borgs. perhaps something like this? I have some “EasyCast Clear Casting Epoxy” (link) used for casting objects from Tap Plastic. I placed a thick coat on a test pieces and the edges around the surface ate it all up leaving a nice center of thick deep wonderfully clear surface. Is this what you was referring too? It’s tintable. I would have to preseal the surface with something, IDK with what. As you can see I am pretty ignorant of this kind of stuff but I am learning.

A
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ok here is what I am working with….

This object is 23” wide, so it’s large and beautiful. The second picture of the edges come out quite well here and there. The fourth picture with the flash on really shows the paint globs but the good thing is there is no pitting from the MDF fibers themselves, just poor finishing technique.

As you can see in the third picture the surface is not very smooth. This is three coats of latex paint, sanded down to 220 and a thick layer of clear coat polyacrylic. Out the gate one issue was I did not thin the paint.

To get a better finish I will need first use a primer, such as kilz, sand it down, spray the paint (water downed slightly), sand it, then clear coat, and clear coat. This took about two hours to finish, most the time was sanding the edges down by hand. I know and working with a OSS and flap wheels to cut this time down.

But if using a oil-based paint, epoxy, or laquer would reduce the steps and still present a wonderful finish I am down for it.

Thanks again.

-- "Gentlemen, you can't fight in here this is the war room!"

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