I just built a small step stool out of mdf for my daughter. I went to finish it with a can of white rustoleum enamel spray paint, the paint did not want to stick to the mdf. On the exposed edges the paint seemed to disappear as it was sprayed on, causing the paint hitting adjacent surfaces to run. The paint on the flat surfaces seemed to go on strange.
Do you need a special primer or paint for finishing mdf? Can you use latex, oil base, or does it have to be some kind of specialized spray on finish?
Thanks for any help. I’ll be sanding off my first coat, and hope to have this problem solved before I try again.
Replies
Never used Rustoleum, just latexes and stuff called "Cabinet Cote" both of which have worked fine, both brushed and sprayed. Sounds to me like you might try a veryyyyyyy light "hang" coat to give the subsequent coats something to hang on to... good luck.
the edges have a more open pore structure.. you need to reprime the edges ( and everything ) before you do finish paint so the finish will have the same surface to adhere to
or ... you could mask the body and spray the edges a couple coats until the pores fill..
then respray the whole thing..
it's usually best to prime with a sanding-sealer for your furniture project.. and sand between coats..
you will probably need two coats of finish after you have all of the prep work done
Edited 9/16/2005 4:49 pm ET by MikeSmith
As mike suggests, the edges soak and soak and soak. They'll drink a quart of paint if you put it all on at once. One way of filling them up and sticking your thumb in the dike is to make a slurry of spackle and put that on cut edges, let it dry, and prime. It doesnt cure it completely, but it helps. And your cut edges usually seem to want some sanding anyway.
I've also heard of (but haven't tried) using grain filler.
"If you pick up a starving dog and make him prosperous, he will not bite you. This is the principal difference between a dog and a man." - Mark Twain
KindaHandy,......Go to a good paint store....You need pre-catylized Lacuer with pigment. I know, it sounds complicated. But, once you do, it you'll love the results. Coats go fast because it's laquer and dries fast. Sand between coats and you'll be happy with the results. Go for it!
InTheCleftOfHisHand
ford
Don't know if you have access to a cabinet shop, but the shop that I worked at taped all the exposed edges with a paint grade plastic tape when we worked with MDF. Course we taped the edges before the components were assembled. Just something to think about for your next MDF project
Sanding sealers are used to seal the pores of wood before painting so the grain doesn't show through as much. They are inexpensive, available at all of the big boxes, and work well. I've never used them on MDF, but it might be worth a try.
I experimented with wood fill thinned to the consistency of thick syrup. It worked quite well.
The only reason I used it instead of sanding sealer is because it was the only thing I had handy at that point.
-Don
Fine Woodworking several months ago specifically treated this subject and recommended primer, I think it was "BIN" which is readily available at Home Depot. Otherwise, I've been using MDF for cabinets and prime with standard latex primer, then finish with a Sherwin Williams product that's water clean-up but is similar to enamel in appearance. This is their "Pro-Classic Alkyd" and you can get it in a gloss and tint it.
Good Luck,
Pascanale
You're right. That product was Zinsser B-I-N http://www.zinsser.com/product_detail.asp?ProductID=10
Upon seeing the article in the magazine, I tried it on an MDF wainscot paneling project in my guest room, and I was pleased with the results.
Tejonista
Sorry Kindahandy,
I forgot to address the endgrain issue. And this too, is addressed in the Fine Woodworking issue. I believe he used a thinned down woodglue to size the edges. I know spackle can be used, too. Primer otherwise will still take a few applications to build up with sanding in between.
Pascanale
Yeah, thinned down wood glue works, so does the paintable edgebanding mentioned earlier.
With lacquers, all the systems I've worked with (usually post-catalyzed but sometimes precats) go something like this: 1 coat transparent sealer, I coat pigmented primer, 1 coat topcoat. My supplier just turned me on to a new trick on a biggish job....we tinted the primer the same colour as the topcoat. Works great, but I'd never thought of it before even when I was running a commerical spraybooth.Cabinetmaker/college woodworking instructor. Cape Breton, Nova Scotia.
Adrian,
What's the feature in tinting the primer? I've recently invested in Devilbiss spray equipment and ventured into lacquer spraying with great success. Still, I'm rank novice. I've learned not use semi-gloss or satin undercoats even if the finish to be such--the undercoats will build up "cloudy". But the tinting I'm not sure about your reference.
Pascanale
If you're spraying a dark colour, makes it much easier to get evertyhing looking good without multiple topcoats....most of the new topcoast are deisgned to cover in one or two coats. Also, if you get a chip or scratch through the topcoat, if the primer is tinted the same colour, it's a backup.Cabinetmaker/college woodworking instructor. Cape Breton, Nova Scotia.
We just finished making an MDF laundry room, and all we did for the edges was sand from 180 down to 320. Then we sprayed thinned down primer, regular primer, then the finish coat. The sanded edges are indistinguishable from the face.
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People are entitled to their own opinions; People are not entitled to their own truth.
Jacob
Use an oil based primer or a shellac based such as BIN by Zinnser. For the oil try Kilz. Be patient, sand , apply 1st coat let dry. Sand, apply second coat to all cut edges. Sand again, the recoat entire project. I would never use a latex paint on a project that I built for my own use. Use the oil base topcoats. It will take longer to dry, but , the results will speak for themself!
Good Luck, Jim Z
Couple months back, FHB had a great article on painting MDF. Not sure if you can do a search for it or not.
I referenced the same article in my suggestions but I couldn't find the actual issue either on or in my library. I don't know about you, but Taunton's website search of their publications always turns up empty...and I'm positive I read the article in their publication(s). I'm constantly trying to find old articles and spend too long either shuffling through stacks of issues, reading the annual index or trying their on-line search engine, all for naught.
Years ago, a 3rd. party sold a simple DOS-based floppy disc program that worked wonderfully for finding past articles in both FWW and FHB. You updated yearly from the company at a nominal cost, too.
Pascanale.
Thank you all very much for your suggestions. This time I took the easy way out. I just continued to apply several light coats on the edges using the spray paint I already had. After a while it built up enough to match the surrounding areas. This was obviously not very efficient though.
For my next project I will try some of your other suggestions. Thanks again.
White or yellow Elmer's glue thinned abut 1:1 with water use a paint brush to put it on works great.