Sealing and painting an MDF router

[henrydavis]

I purchased a Joes 2006 2x4 CNC this past weekend and the seller kept it to bare MDF, as he was using it in his basement. I will be keeping it in my garage and would like to protect the MDF from the climate here in central Ohio.

Since it is already assembled I will have to disassemble it in stages and paint it. This would be a lot easier to do if I had an unassembled kit and getting the torsion box painted with all the joints is going to be tricky.

As far as supplies I own I have some Harbor Freight paint guns and one of their air compressors. I will link to them below. I have never used a paint gun with a compressor in my life and only purchased them because they were on sale. If I were going to use one for this job I would need to use one with an easy to apply paint/protectant. It's currently in the mid-30's this time of year but I do have 3 dedicated 20A circuits in my garage and can get it to about 60 degrees Fahrenheit with three 1500 watt heaters.

So, with that information, what method of protecting this MDF CNC would you use? I'd like to do it fairly soon as it's sitting in my garage unprotected. Yeah, my wife won't let me bring it inside!

Thanks!

http://www.harborfreight.com/cpi/cta...emnumber=94667

http://www.harborfreight.com/cpi/cta...emnumber=92126

http://www.harborfreight.com/cpi/cta...emnumber=47016

http://www.harborfreight.com/cpi/cta...emnumber=66222

[stangtjk]

I don't know anything about sealing MDF but I've used a lot of those cheap $15 paint guns and they are great for the price. I might not use them to paint a car but they are awesome for other things.

I actually did use them for the epoxy primer on my old mustang after I stripped it down to bare metal.

[valdy]

Two coats of basic sanding sealer or varathane water based clear varnish will do the trick.

[henrydavis]

I wanted a non-MDF finished look so I would like to paint it. I did some research on the internet and a lot of guys suggest mixing Elmers white glue 50:50 with water and applying that instead of sanding sealer. Then I guess I could sand it down and apply spray paint. Any thoughts?

[mlabruyere]

Originally Posted by henrydavis I wanted a non-MDF finished look so I would like to paint it. I did some research on the internet and a lot of guys suggest mixing Elmers white glue 50:50 with water and applying that instead of sanding sealer. Then I guess I could sand it down and apply spray paint. Any thoughts?

Maybe but I think the Elmers will just ball and clog the sandpaper.

[fireballcnc]

I've painted tons of it....

There are a few easy...(relatively)...ways...

Use Zinsser BIN shellac based spray primer. Shellac is an excellent
sealer, the stuff dries fast, and has a high solids content for easy
use. I use Krylon over that for color.

Drawback is tiny chips show the white base coat...and the tiny chips do
happen.

OR....coat with a brush with *yellow* wood glue mixed 30-60%
with water. Give a few coats drying and sanding between them.
That works very well. The cheap yellow PVC wood glue is all you need.

My new experiments involves spraying it with color first and wiping
it into the MDF while still wet. That's an attempt at dying the MDF,
so the accidental small dings it gets doesn't show as badly. Then the
yellow glue technique for sealing the color in. Then a color coat.
More time consuming and definitely more messy, but it's a nicer, more
durable coating.

Quickest & easy is the Zinsser shellac. A Very Good sealer for MDF....

(Keep in mind there are a few different qualities of MDF. Crap MDF is
practically unseal-able, while a good quality works very easily.)

[ger21]

Best way, imo, is to get some thin epoxy, like West Systems, and seal with that. When sealed with epoxy, edges can be sanded to a glass like smoothness, and you'll have no trouble painting at all.

[John Bennett]

MDF used for kitchen cabinet fronts are first primed with an oil based primer. If a water based primer is used, the surface will swell and be rough with small wick fibers that you will have trouble sanding down. With the oil base primer, you do not swell the surface and then you can topcoat with any compatible paint. Many kitchen cabinet door fronts are made with a solid piece of MDF, routed, sanded, primed, and top coated with a lacquer coat that dries to a glass like finish.

[valdy]

Ok, it depends on what you want you cnc to look like . I will probably be sealing mine with sanding sealer, like I suggested and then give it 1 or 2 coats of Tremclad metal paint. You can make mdf look like metal ( as I am a patternmaker / modelmaker and make wood look like metal I know what im talking about ) just make sure you seal the open edges of the mdf well. What i have found is if you use the sanding sealer, do not sand it down untill you have given it the first coat of paint then rub it down with 320 grit, then give it the 2nd coat.
Hope this helps
Dave

[henrydavis]

Originally Posted by fireballcnc I've painted tons of it.... There are a few easy...(relatively)...ways... Use Zinsser BIN shellac based spray primer. Shellac is an excellent sealer, the stuff dries fast, and has a high solids content for easy use. I use Krylon over that for color. Drawback is tiny chips show the white base coat...and the tiny chips do happen. Quickest & easy is the Zinsser shellac. A Very Good sealer for MDF....

My local Meijer store is clearancing out 1 gallon buckets of Zinsser BIN for $13. Would I be able to use this with one of the paint guns I linked to above? Again, I've never used a paint gun in my life. I would rather use a spray than a roller etc. because of all the joints and curves I have to paint, especially with the torsion box that is already assembled:



I'm going to paint it white to match the HDPE. Any suggestions on an easy to use white paint I "could" use with one of my guns? Also, I looked at two stores that carry Zinsser BIN and they don't carry it in a spray can. That would have made things easier. Though, I would like to get some practice in with my guns.

Oh, and one more thing. Since it's about 40ºF here in Ohio (I can heat my garage up to 55ºF) should I bring the CNC inside to warm up and dry for a while, then take outside in the garage to paint in the 55ºF? Sorry for all the newb questions but I want to make sure I get this right the first time.

Thanks.

[fireballcnc]

Personally, I'd likely just use a good quality brush...*because* of
all the contours and curves. Spraying could be very messy and cause
lots of runs/drips.
Paint will soak in easily at one place (edges) and not-so-well at others.

I'd get it warmed up and just take my time with a brush. I doubt there's
a fast way to do it with a gun, unless you have a good bit of practice
with a spray gun. Spray guns are like everything else....they take practice
for getting good results.

Ace Hardware should have the spray cans, but IMHO...a brush is going to
give a better looking finish with a great deal less trouble and mess.

I hope that's useful...

[voltsandbolts]

I brushed mine with clear “Polycrlic” (water based poly) I did a couple of coats to seal it before painting but liked the way it looked so I left it that way…