I make wire brushes from KD Beech. It is a problem when we ship to California because 5% of the brushes split by the time they get there. I'm thinking it's due to pressure changes when crossing the mountains. One thought I have is to let the blocks sit for a month to let them normalize then drill and fill them. I tried to talk to the tree designer about the warrantee.
More likely, it's due to humidity changes.
You might talk to your supplier about drying the lumber to a lower moisture content. That will drive up your lumber costs, though, and probably by more than your current five percent loss rate.
Do you have to use beech? Birch might be a better choice.
Birch is too soft. I can use Maple but the cost...
You'd better check that again. Yellow birch is only about four percent less hard than beech -- and sweet birch is about ten percent *harder*.
Have you looked at steamed beech. My supplier has it for about the same cost and if I remember right he said that the steaming not only evens out the color it also relieves the internal pressure created by drying and makes the wood less likely to split. At least that's what he told me. Hope that helps. bc
Humidity is usually the cause of splitting, specifically changes in humidity that are not even within the wood. One part dries faster than another and this stresses the wood and can lead to cracks. I am guessing these items are not finished or have a very porous finish. A better finish will slow down humidity changes and reduce cracking. Brad ==== trim==
I suspect it is the drilling. I assume you have a 4/4 thick piece of stock and you drill a bunch of holes 1/2 to 3/4 of the way through in a very tight patten. Then those are then filled with some bristles. Drilling all those holes opens the wood up to some incredible absorbtion and exhaustion (is that a word) so the speed at which this wood will start to dry out or absorbe is radically accelerated with all that new surface area and path to internal zones.
I think maybe not drilling so deep, drilling and letting set for a month or making the handle thicker or devising some pattern of kerfs to help equalize the stress on the non drilled side mught be the ticket.
Another possibility might be to dunk the whole wood piece in shellac before gluing in the bristles. This also might minimize the absorbtion.
BW
If everything else is fine, ie if you could magically teleport the brushes to the destination they would acclimate fine without cracking, then I would look into how to package them to insulate them from the changes they see in shipping rather than how to change the product.
-Leuf
Perhaps -- but I think substituting yellow birch for beech should be the first try. The large difference in hardness imagined by the OP just doesn't exist, and birch is more stable.
Some items like ice cream and potato chips are shipped via the southern route to avoid the pressure problem. I suppose that you could make up a test batch and place them in a vacuum chamber to simulate the atmospheric change.
As a side story when I was driving a truck, I had a pint size bottle of Clorox In my laundry bag and when I got to Wyoming I smelled bleach and found that the pressure in the bottle had broken the cap and the stuff had leaked all over my bunk. Punched some nice holes in my sleeping bag and my jeans. Also once when I stopped to make my self a sandwich, I twisted the top on the mustard bottle and the pressure inside sprayed my face and shirt with mustard.
5% loss? Man, what a beech.
That's true!
Hole depth must be to spec, dimmentions must be to spec. The brush goes into food service and no chemicals are allowed. Unfortunatly, there's no room to increase cost or raise price.
I talked to my supplier and the cost shocked me!
Well, easy solution is to climate-control the trip. Assuming that it's not the wonderful dry heat of the interior of CA that's doing you in on arrival. Beech isn't the nicest wood, and the rays are a built-in point of weakness which your QS methods might be putting at even greater risk.
Beech sure splits easily for the furnace.
Shellac is food-safe. For that matter, pretty much any cured finish is food-safe, but I'm pretty sure that shellac already has FDA approval (considering that it's used to coat candy and pills).
Maybe you need to talk to another supplier.
Here's another option for you, too: buy birch, but in a lower grade.
Presumably, these brush handles are fairly small items; I'm guessing that you could probably cut one from a blank about a foot long by an inch or so square, no?
You don't have to buy FAS or Select lumber to get clear cuttings that small; #2 or #3 COM will work just fine. Sure, there's more work involved in cutting the stock, but the difference in the cost of material is *huge*. And the waste material can be burned to help heat your building.
Whether that difference in material cost is big enough to compensate for the extra cost in preparation is something that only you can decide. But I think it's worth considering.
Valid points, all. However, this is surely a twisty road. I've discovered that low grades of lumber have huge hidden costs of labor per good block, electricity, handling costs and disposal costs. I know it doesn't make sence but our studies over the past 20 years or so show it. I think that with a huge decree of computer controlled automation, it could work but we're not there.
If you have a 5% loss from damage, there is at least 4 1/2% room in the price to correct it. .
Good point! My first experiment will only cost inventory expences to age the blocks for a month or so. I'll keep records and lot# and every part has a date of Mfg, stamped when it gets made into a brush. I only have beech with no finish approved, this customer took 6 months to approve a change in handle screw head from Philips to square, and they freaked about that...I had to beg.
I'd say it's certain. People fly airplanes made with wood. They experience much larger pressure changes applied much more rapidly and they do not (usually) fall apart at altitude.
(To Mr Gardner) Are you up on the North Coast? Is there a difference in 'survival' rate between brushes made in the (dry) winter vs those made in the (humid) summer?
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