Paint Cracks at Joints in Five-Piece Doors

Painted wood stile-and-rail raised-panel doors almost always show cracks at the joints. It's important to inform customers of this before the sale ó they might prefer to go with one-piece MDF doors. August 30, 2007

I have been building and finishing my own cabinets for several years now, mostly stain and lacquer finish. I have a project in the works now that is all maple. I am using Gemini pigmented vinyl sealer to get the base coats of the off-white finish that the customer wants and top coat with Gemini pre-cat semi gloss. These are turning out beautiful in my opinion and the opinion of almost everyone who has seen them, except the homeowner. He is very fussy and can't seem to get over the fact that there will be hairline cracks in the 5 piece doors and in the joints of the face frames.

When we signed the contract it was understood and in writing that the doors would be 5 piece Maple, and this is what he wanted. We donít use particleboard or mdf to make anything. A couple of other cabinetmakers in the area that he talked to said they only do painted doors in mdf and that I should have made my doors out of 1 piece mdf.
Everything in our shop is made from solid wood and plywoods in a more traditional method without the use of mdf and this is why people choose our shop - because of how we build.

My question is, are the hairline cracks acceptable with this type of cabinet and construction method? Is my customer just being too picky, or does he have a valid point? Please remember that he requested the 5 piece solid wood doors.

Forum Responses
(Finishing Forum)
From contributor A:
He's being picky. No matter how much coating you apply, there will always be some movement in the components, resulting in hairline fractures of the coating. If he wanted a seamless piece he should have requested a seamless material. It's like saying "I can see the seams in a suit" "Yes, that's where the sections were sewn together".

From contributor B:
If he wants plastic in his kitchen, that's what he should have ordered. Wood is not plastic and will not ever look like it. No matter how good the finish is when applied, over time the wood will move and create those hairline cracks, and thereís no way around it that I've ever seen.

The lesson is, always have or make a sample door to show the client exactly what they are getting. With one client who was concerned with the toughness of the finish, I went so far as to make up a panel for her to destroy. I told her to do everything you would normally do to a cabinet door and see how it holds up. Then do things you would never do to a cabinet door and see how it does. If, after that, you think the finish needs to be tougher we can look into other options.

The point is the more you can show the client exactly what he is getting, the better off you are. Your client wanted something he didn't fully understand. And it's always tougher to explain after the fact.

From contributor C:
I believe it is possible to build and paint well enough to stop the potential cracking. I built a large kitchen over one year ago. It was beaded inset faceframe with applied moulding doors. I sprayed it semigloss white with MLC Polystar. I had a look at it on Friday. No cracks in the faceframes, except the ones I created when they were installed. I used a lot of 1-1/2" wide beaded mullions. I would expect that joint to crack unless I used epoxy resin. Other than that the only visible cracks are between the applied moulding and the stiles and rails. There are no cracks in the stile and rail joints.

The moulding line cracked this winter, the day the owner cranked his super-duper heating system up to 90 degrees with no humidification, while trying to dry some tiling. I did not expect this kitchen to have so few cracks. It is one of the hardest spray jobs I've done or seen. I live in the Northeast and we have some of the worst temperature and humidity differences throughout the year.

Can a crack-free kitchen be fabricated? The answer is yes. Should the customer expect one? I would say no. I informed my customer that there would be cracking before we signed the contract. I guess I got lucky on that kitchen. I don't expect it to happen again for a few more years.

From contributor D:
I've made a compromise in that my 5 piece doors are solid except the panel, which is mdf. Cuts way down on the cracks between stiles and rails and the panel.

From contributor E:
I do a lot of painted kitchens with wood doors. I make a sample door of the selected finish and door style and on the back of the door is a disclaimer explaining that these hairline cracks are not a warranty issue. I have had jobs where there was no cracking in frames or doors, but it will happen. Maple is movement prone. I use soft maple.

From contributor F:
You could try two things. The first is to cut a small groove on the joint with a V point router bit and leave it. The second is to apply a very thin coat of auto body filler over the joint. Between coats of sealer and topcoat a bead of painters caulk around the panel will help things also. One last note - if you want a really high gloss finish with your painted cabinets try a white lacquer undercoat for sealer and then QD enamel for a topcoat. The only downside to the QD is that if you have to recoat the door you have to either do it wet, or wait 72 hrs.

From contributor G:
Whatís wrong with a solid mdf door? Anytime you have more than one joint, youíre going to have a slight seam that will eventually telegraph through the coating. A one piece mdf door or panel will take a beautiful finish and looks much nicer than plywood that has a painted finish. If you treat the end grain with a watered-down glue solution the primer will easily fill in the slight imperfections and will yield a keener finish than a five piece door made from poplar or maple.

From contributor H:
Most of the painted doors we finish (90%) do not crack on joints. Usually when they do it's due to poorly glued or constructed doors. For painted work mdf really is the best option though. No joints, no movement, no caulking, no grain.

The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor I:
I always build five piece paint grade doors from poplar and I've never had an issue. I join them with your standard tongue and groove, using birch MDF core plywood for the panel. When I assemble them I use plenty of glue and I even glue the panel in, nailing it tight to the front through the tongue from the back. Unless itís a raised panel, there's no reason you canít glue the panel and nail it. I donít do the quick 'nail it' and take it right out of the clamps. I leave them clamped at least 45 minutes. You may want to try a stronger glue like polyurethane glue if your butt joints are showing cracks.

Comment from contributor J:
You can also apply a pure vinyl sealer to the joints before applying the basecoat, the vinyl is durable and flexible which helps compensate for the shifting of the door...assuming the doors aren't poorly assembled and won't shift like crazy.