With painted cabinets, there's not much point in using solid wood for panels. It's more work, and prone to more problems. That said, of course you can do it. In fact, the inevitable across-the-grain movement of solid wood is the reason frame and panel construction exists.

Unless you have a lot of wide lumber, you'll find yourself having to glue up stock to make the larger panels from. You need to have a good clamping arrangement for this, and some way to flatten and thickness them after glue-up.

My biggest concern having to do with the stability of the wood is that when (not 'if') the panel shrinks, it will break the paint film between the frame and panel, and probably expose a strip of unpainted wood along the edge of the panel. You can prefinish the edges of the panels before assembly, but that's more work too. In any case, I'd check the MC of the wood before building these things, or simply let the rough-cut parts season for a week or so in a heated space before final machining and assembly.

There are several reasons why solid wood in old furniture is so stable. One, the furniture that cracked is mostly gone. Two, the wood is denser old growth wood which moves less. Three, the panel pieces are wider, meaning less different grained pieces to move differently.

Plywood is demonstratably more stable than solid wood for todays lumber---that is the major reason for its wide useage in cabinetry. But, in good cabinets, the face frames, drawer and door fronts, and trim are all solid wood---no plywood---which is used on the sides and countertops---where it is not seen.Veneered MDF is not as stable as plywood since moisture and humidity affects MDF much more than it does ply.

Poplar is fine for painted kitchen cabinets. Yes, it is softer than even soft maple, but most people are not that hard on the actual cabinets. Plus, soft maple can be a pain to sand smooth enough for painting as some varities feather when sanded.

thanks, those arguments make sense.

Just to follow up on Handymac's comments about old-growth wood, it's worth mentioning that there's no consensus about what "old growth" means, and consequently there's no consensus about the properties of old growth wood. Often it's taken to mean wood that grew slowly and so has a relatively large number of rings per inch. This has fairly predictable aesthetic implications, but whether it makes the wood heavier or lighter, stronger or weaker, more stable or less, depends on the species.

Here is a link that might be useful: Interesting discussion on WoodWeb

thanks, jon, that was interesting. old growth is a shorthand way of saying dense rings, but dense rings don't exist only in old trees.

are there any woodworkers today who DO use solid wood in panels? i dislike plywood because of the toxins used in the adhesives, and because if they're damaged, the inside is different than the surface. i know this doesn't bother most people at all, but i don't like those aspects of it. otherwise, i know it makes cabinet work much faster.

Sure, of course solid panels are still in use. In kitchen cabinets, for example, It's pretty tricky to put a veneer on any sort of raised panel, and almost impossible if the panel is an arched-top design. You're talking about painted cabs, though, for which solid wood is kind of a rare bird. Even so, almost any question that begins with "are there any woodworkers today who..." is going to be answered affirmatively. Wood is everywhere, and people do all sorts of stuff with it. Your particular, personal desire to use solid for the panels is fine and you have every right to pursue it. When professional types say that it's not done, they really mean that it doesn't pay (literally pay, as in increase your business's profitability) to do it that way. Businesses have to shape their shop practices on the preferences of their average customer, not the exceptional ones. If you love solid wood enough to devote the extra time, money and labor to use it, then more power to you.

Debbie, I just figured out what you should do. Pick an average cabinet door size, and build two of them. Build one with a plywood panel, the other with solid wood. Go through all the steps; glue-up the solid panel, machine it to final thickness, size it to allow for expansion and contraction and to fit snugly in the groove, pre-finish the edges, assemble and paint both doors. Keep track of how much extra time the solid panel requires, multiply that by the number of doors you'll ultimately be building, and see whether the payoff is worth the cost. Whatever decision you make, you'll be able to proceed with confidence.

Thanks for the words of encouragement. I'm an amateur, and it makes me a little insecure that virtually everything I read or hear on this topic rules out using solid wood. I'd like to try it.

The question, then, is how can I make them as stable as possible? I imagine that using quartersawn wood would make the least expansive panel, but it seems criminal to paint it! I'm wondering if two poplar boards glued up would make a stable enough panel? Or would poplar not be a good choice here? (Since the cabinets will be painted, I guess I could use poplar for the frame and another wood for the panel.)

I think I'll try those little rubber things you put between the panels and the frame's grooves (I forget what they're called) to allow for expansion. And I'll pre-finish the edges.

Any other suggestions (about wood species or cut or method of assembly) that could make a difference between a solid-paneled door that'll last and one that won't?

Thanks again

Yes, quartersawn is more stable. The random ring orientation in glued-up panels does moderate some sorts of movement. The little rubber things you're thinking of are called space balls; I haven't used them.

My impression is that you may be underthinking and overworrying. It would help if you were to clarify just what sort of stability you're hoping to achieve. Exactly what sort of problems are you worried about? It's not as if solid wood panels will make your cabinets implode six months after install. Solid wood will move, and it will break the paint film in places. Period. If you're not okay with that, skip it. If you are okay with it...

Leave enough room for the panels to expand in humid seasons without pushing the frames apart.

Make sure the panels are buried far enough in the grooves that shrinkage in dry seasons won't pull the panel completely out of the groove.

Don't make the panels so thick and the frames so delicate that the frames can't hold the panel flat against its will.

Make sure the wood is dry, store it in a climate-controlled environment, make sure your joinery fits and is assembled well, and you may be surprised at how forgiving this all is.

jon, do you mind a couple more questions? First of all, everything you've said is very clear and to the point, so thank you! I really appreciate that.

From the reactions I get from people when I mention solid wood panels, I kind of did expect them to implode. I didn't know what kind of problem to expect. From what you're saying, I gather that, yes, the frames and panels will move. But if I prepaint the panels, the paint film breaking might be avoided. If I leave the edges of the panels deep enough but not too deep, any panel movement will be OK.

I'll probably make the frames 1" thick, because that's what my boss does, and I like it.

Question 1): Given a 1" frame thickness, how thick do you think the panels ought to be? I'm thinking 1/2"? (In terms of the relative thickness of the F and P you mentioned above.)

Question 2): Is 1/8" a good size gap to leave between the panel edge and the inside of the groove? This seems a little small, but that's what I've read. Would making it a little bigger, say 1/4", be better?

Question 3): The climate in my shop is very different than in my kitchen. The shop (in basement) is cold all winter. You say to keep wood in a climate controlled environment. Is there an ideal? I hate to heat the basement, but since I have to, do you think keeping it at about 50 degrees is good enough? I'll buy the lumber rough, let it come to a stable moisture content, then joint and plane it. In order to keep it flat after this, I guess I have to keep the shop at about the same temperature as it was while the wood was acclimating? Once the cabinets are assembled, will there be a problem bringing them up to the kitchen (climate change-wise?)

I feel silly asking all these questions, but the shop I work in does things in a way that I won't be doing, and it's hard to get specific answers to questions like this by reading.

Thank you again.

Debbie

1) Panels that are half to 2/3 the thickness of the frame are par for the course. It's not a hard and fast rule, though, because you need to consider the width of the frame members as well as their thickness. Rails and stiles that are 1" thick and 1" wide would meet your criteria but wouldn't work well. I imagine this is fairly obvious, but I'm just making sure.

2) The size of the gap needed is proportionate to the width of the panel. 1/8" is probably fine for most kitchen cabinet doors. Especially wide doors and/or unstable woods could require more. Remember that you only need that gap along the edge-grain sides of the panel . Where the panel's end grain butts into the groove, no such gap is required(again, I don't know what you already know).

If you want to get into the math, pick up Bruce Hoadley's Understanding Wood. By consulting various charts and formulas in that book, you can learn that the moisture content of film-finished, kiln-dried wood kept indoors in most of the U.S. varies within a range of about 8% over the year. My guess is that that presumes very dry air in the winter (no humidifier) and humid in the summer (no central air). Obviously YMMV. Anyhow, the book has charts of average tangential and radial shrinkage of various species, and this information can be used to calculate the amount of movement you need to allow for. Yellow poplar is listed at 8.2% tangential (flatsawn), 4.6% radial (quartersawn). Imagine a panel in yellow poplar, 18" wide. We'll say it's rift sawn, and use 6.4% as the shrinkage number. Over a MC change of 8%, our hypothetical panel would grow (or shrink) by about 0.33". In other words, an 18" wide poplar panel built into a door with only 1/8" gap per side in the driest part of the year could conceivably grow enough to bottom out in the slot and push the frame apart six months later.

3) I'd say 50 degrees is borderline, but workable. The basement shop can be a bigger problem in the summertime, because the coolness (in the absence of air conditioning) raises the relative humidity; summer humidity is high to begin with, so a shop environment that raises it further is problematic. In the winter, however, humidity is likely to be on the low side, so you've got some breathing room to tolerate the cooler environment. Below 50 degrees, however, many glues and finishes don't work so well.

--Jon

Something I wrote wasn't sounding right, so I went over my figures. I goofed.

The 8% is the seasonal average MC in most of the country, not the breadth of the fluctuation. It looks like typical seasonal variation is within a range of about 2%. That changes the movement calculation considerably; the hypothetical 18" riftsawn poplar panel would move less than 1/16" between winter and summer. Even a flatsawn panel would move less than 1/8" overall, so the 1/8" gap per side should be more than enough. This does presume finished wood; an unfinished panel could move several times as much.

Thanks for all the thought you put into this. The math is a little confusing to me, but getting a reference book like that is a good idea. 25 years ago I took a one semester, half-day class in cabinetmaking. Before that I literally didn't know a wrench from pliers. I learned enough to jump in and hack my way through home projects. More recently I've become interested in dong GOOD work, and getting a job with a local cabinetmaker has helped there. But there's still tons I don't know, having worked almost always alone without help. (My husband used to "help" me, but he has no interest in or patience for woodworking, so we decided he'd stay out of it all!) I wore out my old contractor's table saw, threw out the bag-style dust collector, bought a powermatic table saw, an 8" jointer, a clearvue cyclone, and am almost ready to go. I'm really excited, and hope I can finish before arthritis sets in too heavily!

Thanks for all your help! I'm sure I'll need more later.

Debbie

You're welcome. I didn't really explain the calculations, so don't feel bad about not getting the math. Good luck with your project.