Need advice on painting / finshing MDF

[dewi1219]

I am building a window seat with vertical shelves on either side (all from MDF) for a child's room. My main hobby is speaker buildling, so I enjoy the ease and economy of working with MDF, hence the choice to use it for this project. Everything will be painted white, but I want it to be as smooth and durable as possible. I built this entertainment center out of MDF and simply painted it with flat black latex for a sort of "rustic" look:

I like it, but I know it wouldn't be extremely durable for a child's room. So I'm looking for suggestions on how to proceed. I thought about painting with either latex or oil and then topcoating with a satin poly, but being a novice at finishing I don't know if/what poly works best with latex or oil based paint. Also, I'm not sure what type of application is best. I have both an airless (cheap Wagner) sprayer and an automotive type HVLP gun, but I honestly prefer to brush or roll shelves because it is can be difficult to get into all the nooks and crannies with a sprayer. However, I am trying at all cost to avoid brush strokes in the finish. Any advice is appreciated.
Scott

[jlm]

My first suggestion would be to stay away from latex if you're looking for a kid-resistant finish. Latex is put in paint to make it flexible and less likely to crack, but it also makes it softer. Some latex paints will eventually harden, but some can stay soft for a very long time. Putting poly over latex is just putting a hard finish over a soft one, so it's not really ideal. I'd go with an acrylic or oil-based enamel for the paint, and top-coat it with a water-based clear coat (Polycrylic, maybe?). An oil-based polyurethane will tint the paint color yellow, so I'd stick with water-based.

Now I'm just speculating, but I'd probably go with a flat paint and put whatever level of gloss you want in the top coat. That would probably increase durability and help the top coat bond to the paint. Since it's MDF, it's certainly cheap and easy enough to make up test samples and see what the final result will look like.

Depending on how you plan on assembling it, you might consider cutting all the pieces first, masking the glue joints, and painting all the inside surfaces while it's flat, to get a good clean finish in the corners. Like you said, spraying is difficult in deep corners. If everything's flat you can roll the paint on with a high-density foam roller and get a good smooth coat (and even sand between coats if you want a really smooth finish). Then peel off the tape and glue it together. It can be tricky, depending on how complex the parts are, though. Just a thought. I built a small bathroom cabinet this way, and finish came out quite nice, no pooling the corners, etc.

[dewi1219]

Thanks for the reply, Jim. I'll look into enamels to see what my options are. Is it possible that an acrylic enamel might be tough enough without a topcoat to stand up to the abuse of a child? I'm looking for an eggshell or satin finish, so I was only planning on a topcoat for protection, not for sheen.

The base cabinets and bookshelves for the sides are already assembled, so pre-painting before assembly is out. I use a lot of glue, and I'm messy with it so that idea was shot down from the very beginning
Thanks.
Scott

[Uncle Cracker]

Someone told me not long ago that they had experimented with epoxy paint (I think they used Amerflex) on MDF with good results, although I have not tried it myself. Somebody else here might have. You'd have to spray that on, though, methinks.

[jlm]

Non-latex acrylics can be pretty tough. You might see what higher-end paint suppliers like Benjamin Moore or Sherwin-Williams have to offer in that area. You probably won't find anything too impressive in the hardware store, so go to a real paint store. See if you can get a small sample pot to test with. Paint it on a scrap of MDF and bang the heck out of it with your kids' shoes and toys and see how it holds up!

Also, remember that you'll probably have to give any paint several days (sometimes weeks) to fully cure-out and achieve full hardness, so if you can keep the kids off of it in the beginning (or assemble it somewhere else and let it cure for a week or two before you put it in the kid's room, you'll probably get longer life out of it. I painted some cabinet doors with "kitchen and bath" paint, and was very disappointed, because it chipped and scratched very easily at first, but after three weeks or so, it finally hardened into a very durable surface.

If you've already got a lot of it built, this advice might be too late, but rounding the edges can help a lot in reducing visible wear and tear. A small roundover lets the paint lay thicker on the edge, since surface tension of the paint always causes it to pull away from a sharp edge, making the paint film thinner over a sharp 90-degree edge. If it's a window seat, you might at least consider rounding over the top lip where legs will dangle and rear ends will slide on and off. A sharp corner there will probably wear through pretty quickly, unless you're putting a cushion or upholstery of some kind on top.

[dewi1219]

jlm,
Thanks for your input. The roundover idea is a good one, and I plan to do that where possible on the base cabinet tops, etc. for safety's sake as well as to help preserve the paint. And yes, there will be a cushion on top of the window seat.

As for the paint cure time, that won't be a problem. This project is for a baby that we are adopting, and he isn't due until Christmas day. Even then it should be several months before he starts crawling all over everything

[eezlock]

painting MDF?

Nice looking entertainment center in the picture.....and not being critical, just asking a question...is the back panel a painted sheet of AB plywood ?
Just thought I recognized the swirl pattern of plywood in the picture.....
eezlock

[dewi1219]

Yes, it is 1/4" ply - this was a conscious decision I made during construction. The entertainment center is somewhere around 400lbs. as is, so using MDF for the back would have been just too much. It's over 9 feet long and 7 feet tall - that's a 61" TV to give you an idea of the scale. And with normal light in the room you can't see the back - it only shows up in the photo because of the flash from the camera. It is in a downstairs home theater room where I am the only occupant nearly all the time, except when college football is on. I wouldn't put it in our main family room, but it serves its purpose fine. I am a novice woodworker (and even that description may be optimistic!), so I do not take offense to any constructive criticism from the experts here. My projects definitely aren't perfect, but I really enjoy building them. Thanks.
Scott

[ironhat]

Novice? Well, you apparently have some natual feel for woodworking. You rails and stiles match beautifully, the design is pleasing to the eye... heck, it just looks great!

[dewi1219]

Thanks for the compliment ironhat - I really appreciate it. The way I get the face frame to fit tight is by dead reckoning. Once I have the cabinet built, I first cut and attach the stile on one side and clamp the stile in its proper location on the opposite side. Next, one by one, I lay the rails across the stiles, marking the correct length at the location of that particular rail. Then I cut the rails and assemble the face frame with biscuits, etc. and join it to the cabinet. It's the only way I can get a perfect fit. Cutting all the rails and stiles first and then trying to make it all fit together without gaps never works for me. But again, I am still a novice. Thanks.
Scott

[eccentrictinkerer]

You might try Benjamin Moore Impervo paint, along with their primer.

My wife wanted white cabinets in her new kitchen, so I used KD carcases and shopmade doors of birch. I didn't use enamel because it yellows over time. My paint store contact suggested Impervo (she even gave me a quart sample!).

I rolled on and backbrushed primer and two finish coats on 40 doors and drawers. After 3 years of heavy use, (my wife is cookbook writer and editor). the finish has held up extremely well. There are no fingernail nicks by the handles.

I've since used Impervo in my Wagner HVLP conversion gun and it works very well. Good lucK!

[Cike]

My wife wanted white cabinets in her new kitchen...

I noticed that you have the dishwasher under the cook top. How did you get it to fit height-wise? Do you worry about heat radiating downward?

We recently moved our cook top to the kitchen peninsula counter above where the dishwasher used to be, but moved the dishwasher because it didn't seem to fit any more due to the space the drop-in cook-top takes up. Also, I was concerned about heat--even though the cook-top is induction (and thus doesn't get very hot).

C

[dewi1219]

Eccintrictinkerer,
Thanks for the tip on the Impervo paint – I sent you a PM.

[JimD]

You may have settled on Impervo, if not, you might want to consider white tinted Resisthane from Hood finishing products. Resisthane is a water based pre-cat lacquer. You can buy it tinted either white or black. I am making plantation shutters currently which have mdf louvers. Milling the profile on the louvers creates the super absorbent surfaces that are challenging to finish. My first set of shutters were done with three coats of Resisthane with the first coat seeming to take forever because the mdf was sucking it up something fierce. My second and third sets got two coats of latex primer - I used Kilz total one since that is what I had around. Then I put on two coats of Resisthane. They came out smoother and it used much less Resisthane. Too early to say about durability but I am optomistic because Resisthane is rated for Kitchen Cabinets - it has passed a fairly stringent durability test.

Tinted resisthane delivered to my house is between $35 and $40 per gallon. The finish is more like $25/gallon, rest is shipping. I consider this pretty cheap for good finish. I spray it with a Wagner conversion gun but it can be brushed. The problem with brushing is maintaining a wet edge if the project is big. Resisthane can be sanded in an hour so it dries so fast it is hard to keep ahead of it brushing or rolling. Fine Woodworking also rated Resisthane a best buy when they rated water based finishes.

Jim