MDF Paint Peeling

[Heatherdied]

I am putting together two MDF dollhouses, the Alison and the VIctorian Cottage. I primed them with KILTZ and painted them with Home Depot's paint, who knows what brand. The MDF got all grainy after priming and painting and I sanded the clapboards. But I have noticed that if I place two painted boards on top of one another (after they have dried of course) they paint will stick to the other board and the paint and primer will come off leaving bare wood. Now I do live in the Midwest but I painted on low humidity days. I also made sure that I waited to stack the boards until they dried, sometimes months later. Has anyone had this same experience, should I use a different primer? What should I do now, sand the boards and repaint?

[Heatherdied]

Here is a picture of the peeling.

[LLyn M.]

I did read somewhere that MDF is made with formeldehyde so be sure to wear a mask when sanding!!I have 2 houses made with MDF so I remembered reading this for future use!!

[Just One More]

I have the Alison Jr and When it was all together I painted it and it did get all "furry" for lack of a better word. Sanding in between coats I finally got it somewhat smooth but never really the way I wanted after five coats. I never had it peel off but I don't understand about the stacking. What are you stacking? I won't buy another MDF house because of the exterior paint problems. The inside walls are smooth and take paint nicely. The second reason I won't buy another is because they are just too heavy.

[Heatherdied]

What are you stacking?

I am putting one board on top of another when I am trying to conserve space since I don't have enough room to leave all of the boards flat. I can find another way to conserve space then making piles of wood but I wonder if I should use a different primer or paint.

[Just One More]

I would assemble the entire shell of the house and then paint the exterior so you don't have to stack anything. That way it will all dry the same and you can do a section at a time but it won't be boards pressing on each other. It takes awhile for MDF to dry because the milled in siding is more porous than the smooth interior walls. If you stack them the paint on the pieces will stick to each other. I think the paint you are using is fine. I just use paint from Walmart and don't use Kilz unless I need to hide a stain or something.

[Brezavaqt]

Hi Heather-

I love Real Good Toys dhs. I think it's because the rooms are a nice size and they are pretty easy to electrify with tapewire. However, I must agree with Pat...they are extremely heavy, especially if you work with a large one and put additions on it. (I'm forever working on mine and am now wondering where I am going to move it to in my house...but it's going to take my boyfriend and another one of his friends to move it!)

I'm not sure what happened with your paint job...but there's a lot of expertise on this forum...so I am sure someone will be able to help you out. Funny thing about my house is, I never primed it. A painter told me that this particular wood would be okay to paint without primer. And, the paint that I used already had primer in it. My house doesn't appear to have a grainy finish to it. Could it be the kit may have been a little "off"? How long did you have it? I know one rule of thumb is not to put paint/primer on areas you are going to glue...which makes it hard when you try to paint the house before you put it together...

Good luck with your dhs...just remember not to get frustrated! The outcome will be well worth it!

Bre

[Steve_in_PA]

On some materials, like MDF, I sometimes give them a quick spray of clear coat to seal them. This is a harder finish & could help you with your problem.

Steve in PA

[pats]

Hi: I'm working on RGT's Victorian Cottage now. I painted the pieces inside and out before I put them together and used Benjamin Moore paint -no primer - three very light coats, sanding with a brown paper grocery bag after each coat. I think it looks fine, but I like painting wood better. Don't get discouraged; we're all learning every day and I'm sure you will love your little house when it's done!

[Roxxie]

I am building the Vt Farm House Jr. I lightly sprayed all my walls first with spray sealer then painted with interior satin laytex paint. I bought the sample cans at Lowes. Mine got "furry" also but I sanded lightly and carefully between each coat and after 3 coats its nice and smooth ...so far no peeling. I painted my exterior walls before assembling. So far so good. I don't know what happened to yours but I hope you can fix it.

I love that Victorian Cottage. I also like the material of the house because I am a Klutz and I have bumped it and moved it around quite a bit and nothing breaks. It is kind of heavy I agree.

[Sherry]

I've built 2 RGT houses and not had this problem. I bought some good paint at Home Depot, can't remember the brand offhand, and painted it straight on the walls without primer. I have seen paint peel like this before, but usually when someone tries to put latex or acrylic over an oil sealer. Or if you use gloss or semi gloss and put the coats on too thickly. I used 3 light coats and sanded after the first two. Could be yours was just to thick and the paint didn't have time to really cure well. I'd suggest sanding and repainting, that's about all you can do at this point. Good luck, it will be worth the trouble in the end!

[Heatherdied]

Kiltz is a water based primer. The paint I used is latex, BEHR. The kit wasn't old, I stared to to build it when I bought it (although I do not think MDF has an expiration date, lol). I may not have let it cure thoroughly since MDF may take longer to dry. I was told that while it may dry to the touch within a few hours the paint will not cure dry for a couple of weeks and until the I should not put pressure on it. I decided from now on I will use a bonding primer called Zinsser, an oil based primer. I want to see if this primer will work better. I will also not stack the wood. For now I will sand and repaint the parts that have peeled since there is nothing else I can do. I should post some pictures of the house, once sanded and repainted it will look fantastic.

[Sherry]

Don't use an oil based primer if you're planning to use latex or acrylic paint! you will have a mess for sure! Kilz is about as good a primer as you can get and I really don't think that was your problem.

We will be waiting for photos, and I'm sure it will look wonderful. Sometimes you just make a wrong turn or two along the way. We call that 'experience' around here-lol!

[Heatherdied]

From what I understand you can use an oil base primer with latex paint. You cannot use oil base paint and then latex paint.

[justmesue]

Best of luck. I have never had this problem, but have always painted after assembly of the shell. I don't even use primer, just 3 good coats of semi-gloss latex interior RL house paint.

[Heatherdied]

I wanted to update you guys. I called Kiltz, also the maker of Behr paint, and I guess I waited to long between the primer and the top coat. Did you guys know that you have to apply a top coat after 24 hours but before two weeks? The primer gets too hard and the paint has a difficult time sticking to it. I also did not wait the four hours between paint coats, I only waited an hour. I guess I am too slow and too fast all at the same time Also paint on MDF peels and bubbles more than real wood. So anyways, I was told to sand, re-prime and re-paint, what a pain! Next time I know, hopefully no one else here will make this mistake. One positive thing though is I really didn't like how dark the paint looked, it looked lighter in the can. I will paint it a lighter blue, maybe a baby blue or some other light blue.

Thanks for all your comments, I was wondering what you seal the wood with and how you do it. Can I seal then prime? I have never sealed wood before let me know.

Lastly my camera only takes pictures in 2-3 mb so I cant post my pictures here until I can figure out how to take smaller pictures. Instead I uploaded pictures of my Victorian Cottage JR by Real Good Toys on flickr

http://www.flickr.com/photos/42776885@N06/

Enjoy!

[havanaholly]

Heather, I used to seal the wood with Deft clear sanding sealer back when I was concerned about minimizing warping (no longer as much of a concern since building GL/ CC kits, priming serves the same purpose). I don't recall how long I waited between priming & painting the one MDF piece I've ever done, the Grand Ballroom roombox, but I used cheapest of the cheap primer AND paint, and it never bubbled nor peeled; but I also learned to despise MDF as a building material for dhs.

[justmesue]

Maybe I've just been lucky, but I've never used primer. Just repeated coats of interior latex semi-gloss. I usually do 1 coat per day, so maybe that's how I get away with it. I have many gallons of the stuff, as I buy the boo-boo paints wherever they sell paint, cheap. I have a few large MDF houses, and they are still perfect after many years of sitting around here.

[Nileke]

For my half scale MDF cottage I watched a Master Class video at the Dolls' House Emporium site. They use 50/50 pva glue and water to seal the MDF, and leave it to dry overnight before painting. They state that as MDF is porous, you'll need less paint that way.

I haven't had time to start my project yet, but I intend to do this for all the parts that are going to be painted.

[Emerald]

Do I have to sand MDF before painting?  Need new updated info that I see which is 2009.  Any new help is appreciated.  It is just a room box and painting both sides.

[havanaholly]

The one (and only) time I used MDF was a roombox kit and I did not sand or do anything to it; I gave it two coats of paint after I put it together and got on with making it into an atrium.

[shannonc60]

I don’t sand MDF before painting, but definitely after coats. And I usually will do two undercoats (just your everyday household interior waterbased undercoat). I think Heatherdied’s problem was the paint she used. Wood/MDF sheets that have been painted with acryclic interior paint with some sheen (be it satin or gloss) can stick to other surfaces when they are touching, and this probably caused the paint to peel off when pulling the sheets apart. I suspect this because in our real life house, our wooden window sashes (as one example ) painted with acrylic mid-gloss paint would stick to the plastic double-hung window mechanism when they had been closed for a long period. The paint never peeled off, but MDF is sometimes pretty poor quality. My RGT Alison Jr MDF is pretty soft and fibrous.