A Wide-Board Mahogany Countertop
Advice on managing the wood's tendency to move. October 14, 2006
Question
I am remodeling my own kitchen and have decided to do solid mahogany countertops on one 10' stretch. The stock is 8/4 kiln dried, very straight, flat, and wide, the kind of stuff you just love to look at. I've done some research on the web and found the right finish, preferred construction techniques, and method of installation.
Here's my problem. I know that ideally I should rip the stock down to narrow strips and edge glue for the most stability. Second best, rip the stock down to 4" or so wide, and flat glue it. And in general, that is how I do all my wide panels, but I have pieces that are about 9" wide and they are, well… pretty. It would just hurt to have to rip them into smaller pieces. Am I playing with fire here? I don't think it would bother me if they are not perfectly flat over time, and I don't have to worry about callbacks (remember this is for my own kitchen). I'm thinking right now of gluing four pieces up 7"+/6"+/9"+ and a 6" at a finished thickness of 1-5/8" to 1-3/4". And it will be the focal point of my kitchen (my cabinets are nice, but they're simple painted shaker style). As the focal point, I would love to hang on to the wide pieces.
I'm sure most of you can see my dilemma. I'm not looking for naysayers to tell me to stay away from wood countertops - I have done my homework. I'm just wondering if I can bend the rules a little with a wood that is pretty stable and get away with it?
Forum Responses
(Solid Wood Machining Forum)
From contributor F:
My crystal ball is in for repair, so I can't give you my best. But at the very least, fasten the top in such a way that will allow it to expand and contract.
From the original questioner:
I am planning on two fasteners - 1 front and 1 back about every two feet. I will leave only about 1/4" for movement at the back and about a 1/2" slot for movement at the front. Hopefully that's overkill. I may lose some sleep on this one, though!
From contributor J:
Mahogany is pretty stable. Being 8/4, I don't think you will have a problem. But to be on the safe side, I would put a finish (at least the first coat) on ASAP just to seal it.
From contributor R:
Glue it up for appearance. Just make sure you finish the bottom with same number of coats as the top, and fasten to the cabinet so it can float as someone else suggested, and you will have no problem.
From contributor B:
I see no problem at all with what you're contemplating. One additional thing to consider: If you do your glue-up such that the growth rings are oriented in the same direction, then your fastening method may actually have an easier time holding the countertop flat if cupping does occur.
From contributor L:
I have made many wooden countertops. Gee, I didn't know there was a rule to use skinny, ugly looking pieces (LOL). All of my countertops are made from 3 sticks. I start off with 9 wide in the rough and make a countertop around 25" deep when I am finished. Most of my tops have been around for years with no ill effects. The only one I had a problem with is a hand planed pine countertop that was 60" wide. It was in an 18th century home, and ended up having a few stress checks in the middle. They didn't mind, called it character. I had it in the shop for 3 months without a problem (moved my shop while in the middle of a kitchen, such fun). Brought it to them and they finished just one side of it (they finished the whole kitchen to save money), and a week later the cracks showed up. So I should think that if you finished both sides of it with CV or a minimum of a pre-cat or polyurethane, you should be fine.
From the original questioner:
Thanks for the responses. I feel a little more at ease now after reading your replies. I am planning on using the same finish (Target conversion varnish) and number of coats on all surfaces.
Contributor L, I had another thought last night about potential problems, and since you've done wooden tops before, maybe you'll know. I was wondering if I have to worry about the faucet becoming loose with seasonal movement? Also, I am planning on using a good quality conversion varnish, but figure I should probably use West System instead of yellow glue just for that extra piece of mind. I'm especially thinking of the area that gets cutout for the sink. It will be finished, but also exposed to a lot of moisture. Any thoughts?
From contributor L:
You can use the WS epoxy if you wish, but I think it's overkill. As for the cutouts, if you are doing them before you spray, you shouldn't have much to worry about if you give the (cut) edges a good coating of CV. If you cut out after the fact, then a good quality exterior grade polyurethane should be used to coat the exposed wood. As for the faucet becoming loose, hasn't happened on one of my jobs yet, unless they kept it a secret from me. Good luck with what should be a beautiful countertop.
From contributor M:
I don't know if it is overkill or not, but I would fasten the rear screw tight and on the front screws, I would cut about a 1/2" slot into the cabinet for the screw to move with the top. That way, the movement would only be on the outside and the space along the backsplash will remain tight. I, too, would not rip the pieces into smaller strips. Mahogany seems to be truly stable. Look at all of the shaker tables before kiln drying that are 200 years old with two wide boards for the top and they still look great today.
From contributor R:
Any good type two glue should do fine. Powdered, urea-formaldehyde wood glue would be my choice; it's been around for a long time. It does not have the gap filling properties of an epoxy, but this should not be an issue with an edge glued countertop. One issue with epoxy is the fact that it softens with exposure to heat. High tech is not always better.
From the original questioner:
It took a little longer than I had hoped, but the c-top is finished. (Whenever I build something for myself, it takes forever.) Here's a not-so-good picture of the top in the spray room.
Click here for full size image
