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View Full Version : EEK! I've got cracks!



Lowell Bernhardt
12-08-2002, 08:47 PM
Sorry all, but this isn't really related to wooden boats, but it does have to do with wood. (I don't like to venture into that "other" misc. forum ;) )

I bought some hickory from the wood store about 2 months ago. It was 4 quarter planed on 3 sides and supposedly kiln dried. I used this wood to make the bull nose edge for my granite counter tops, backsplashes and for the bar top on the back of the island. When I assembled the top I did have a few small gaps around where the trim butted up to the top (on the island bar). I filled these gaps with wood putty before I sanded and varnished. I would say that the largest of these gaps was about 1/16", so we're not talking about huge gaps here. The other day I noticed that most all of these filled gaps are pulling apart. This isn't a huge deal because I only have one coat of varnish on the top. I plan on about 8 by the time it's all said and done.

Being that this wood was supposedly kiln dried why is it splitting loose? Should I have given it more time to acclimate? Any suggestions? This really has me nervous because I just ordered 400 board feet of hickory form the lumber mill. (disclaimer: I know that this wood will not be dried, I plan on letting it air driy for about a year before I cut into it) I'm gonna use this lumber for the stairs, entertainment center, and kitchen table and chairs. I know thathe Hickory is a VERY hard wood that is very twisted and stressed. I've cut one 1.5" x 1" piece of stock and had the stuff hit the table saw balde and curve off as it was cut like a big peice of cheese. Could this make it break loose?

Thanks,
Lowell

ishmael
12-08-2002, 08:55 PM
Hey, wood moves. This is the heating season up north, and even if wood is KD it picks up moisture and then drys out during the cycle of seasons.

A situation like this, where the wood is not glued to the top, just invites gaps. I don't think I've ever seen stone counters with wood bullnoses before. You've built a loose wood frame around stone, it is gonna move. Unless I'm missing sumpthin', which is likely.

Lowell Bernhardt
12-08-2002, 09:15 PM
ishmael,

All of the kitchen counters have a bullnose around them, all but this one are stone. This one is actually like a hickory table top. The back of the island is raised and will serve as a bar. Actually all of the bull nose trim is staying put nicely. That's why I don't understand why this is moving while the rest is not.

Lowell

ishmael
12-08-2002, 09:28 PM
Lowell,

On further reflection, I'm sure wood framing of stone is common...just not where I use to work.

Describe exactly how this is made.

Mrleft8
12-08-2002, 10:14 PM
Is this particular portion of counter near the dishwasher or sink?
Hickory is fairly unstable wood. My guess is that it is absorbing moisture (or releasing moisture)at a rate greater than the surrounding parts.

Bruce Taylor
12-09-2002, 09:16 AM
You don't say what kind of hickory you used, but they're all dimensionally unstable (much worse than white oak, which is no prize either).

You probably installed this stuff in summer, right? Well, all the atmospheric moisture that your boards picked up when the R.H. was in the 80s is now being cooked out of those boards. Shrinkage is sometimes accompanied by warping and cupping and other evils that can create gaps.

Lowell Bernhardt
12-09-2002, 09:56 PM
I'll Try to post some pics. (still a little fuzzy on that but I will read up on it and try)

In a nut shell, the bar top is most easily envisioned like this: lay 4 1x4s edge to edge. Glue them all together so now you have a 16" wide top. Now take 4 more 1x4s and lay them on edge (vertical)around the top. Glue and nail them to the top. Route all the top edges of the vertical 1x4's. Now install this unit on the back of the island.

As for the humidity, the top was built in October sometime (can't remember the exact date). I didn't know that hickory was really all that unstable.

Any suggestions as to how I could get around this problem, before, I get into building my table and chairs? Is there any treatment that would make the wood more stable?

Thanks,
Lowell

shamus
12-09-2002, 11:02 PM
Lowell, I suspect that your sixteen inch width benchtop will be expanding and contracting by the sorts of amounts you are talking about with changes in humidity. This is an age old problem, and it is for this reason that table tops, panels in frames of doors etc. are generally left free to float. The greatest change in dimension is usually radial, or parallel with the growth rings, thus the orientation of these is important where wide panels are used, quartersawn timber giving less trouble if arranged so that the growth rings are vertical (in a bench top. Fully sealing the top on all sides will limit the rate at which it exchanges moisture with the air, and may limit the effect of short term fluctuations in humidity, but will not beat long term seasonal change. In all, it would be better not to enclose such a panel with a frame, which is basically what you have done, however....

For a really good explanation of all this, and even some figures which should allow a rough calculation of the movement of your timber, see if you can get hold of "Understanding Wood" by Bruce Hoadley.

Bruce Taylor
12-11-2002, 08:28 AM
Lowell, hickory's change coefficient is .00411.

For the sake of comparison, white oak (a relatively unstable wood) is about 12% more stable than hickory (.00365). Honduras Mahogany (at .00238) is 42% more stable.

The moisture in your wood was probably picked up after kiln drying. Wood might come out of the kiln at, say, 6-8% moisture content, but a few months of summer/autumn humidity, or a brief sojourn in a damp warehouse, can quickly raise that to 9%-15%. Put that wood in a heated home, and it will shrink.

Ways of treating the wood? None that I know of. The best you can do (and it ain't much) is seal it well, to shield it from abrupt changes in humidity.

[ 12-11-2002, 08:34 AM: Message edited by: Bruce Taylor ]

shamus
12-12-2002, 08:14 PM
One other thing you can do is store the timber in the house for a while before building whatever it is, to allow it reach equilibrium with the humidity conditions in the house. Doesn't work here very well though, since the seasonal variation is too great, and wimmens get funny about it. Everything in a timber structure is going to move over time, and only thoughtful design can remove the problems.