PDA

View Full Version : Need help on drying a Cherry slab!



Terry Elvers
12-02-2016, 10:19 AM
Good morning everyone.

This is my first post, my first time working with slabs of wood (I normally just buy rough sawn boards) and I bring a problem to the experts...

I recently purchased 2 "kiln dried" cherry slabs for a kitchen table for my wife. She wanted a live edge cherry dining table. Not the sort of thing you can get at HD.

A friend who was a woodworker recommended a place to me. He only ever buys rough sawn boards, so he had no experience with slabs.

I was told they were out of the kiln for about a week and were at 8% moisture. Since my friend had good luck there before, I bought them (>$400).

They were 20-26" wide (each), about 2" thick, and 7.5 feet long.

Yahoo I thought.... :D

So through the same friend I took them to a cabinet shop he had dealt with to be planed and made ready for glue-up. I do not have the 36" planer they did, nor the wide belt sander.

Everything seemd to be going well. We planed the slabs down, and then sanded them with the wide sander to 120 grit. Looked beautiful.

The slabs finished out at 22" wide (each) and 7.5 feet long, and about 1 5/8" thick. I have attached a picture of them being worked. We installed the long dominos every 8".


Then we ran into problems.... :eek::eek::mad:

When we cut the one edge to joint, the wood felt quite wet! Using a moisture meter, we determined the face was 8%, but the core was 21%

So, $180 later I had two beautiful, wet, slabs.

I then took the slabs home to my basement workshop and glued them together to try to prevent as much warping as I could. Normally I would not try to glue wood this wet, but I knew they would warp and be unalignable if I did not get them glued. I attached a pic of this as well. They went together well, used Titebond III, and the long Domino "biscuits".


Now for the questions:

How long will they take to dry in my basement? It is heated with natural gas, as is the rest of the house (on a forced air furnace with A/C).

How long should I wait before finishing them ( I plan to oil them, then add a pour on bar epoxy coating).

What is the best way to dry the slab? Horizontal / vertical / ??? Right now they are just sitting in the basement on sawhorses. Tried to post a pic, but can't.

ANY advice would be most appreciated. Like I said they are now glued together and in my basement.

Just because I got flamed on another board when I brought this up .....
I was not trying to be cheap! I was trying to get my wife what she wants. Like I said before, this is my first time working with slabs like this (and after this mess probably my last).

I contacted the lumberyard, but they are not willing to work with me - no refund, etc. I feel like a fool, and feel like I got ripped off.

Help.

THANKS

Terry

Jamie Buxton
12-02-2016, 10:40 AM
Boy, that would make me angry.

I'd paint the ends with AnchorSeal or the like. It will reduce end checking. I'd fasten several heavy cleats across the table top, to try to reduce cupping as the wood dries. By heavy, I mean 4x4s or so. The table top is going to shrink cross-grain, so the cleats must be fastened in a way that allows a bit of sliding.

The very rough rule of thumb is that 8/4 lumber takes two years to air-dry. But if you have a moisture meter, you're all set: you wait until the meter says you're good.

Prashun Patel
12-02-2016, 10:45 AM
+1 on Jamie's advice: Seal the ends well, then screw in cleats on the bottom through wide holes to allow expansion.

Plan on having to re-flatten after equilibration. You might try to negotiate with the lumber yard to fund that..??? Or you could use the year to become good at handplaning.

If you see some checks or cracks starting, seep epoxy into it. It's hard to stop it, but it does work sometimes.

Terry Elvers
12-02-2016, 11:24 AM
Thanks

I did paint the ends with melted paraffin wax (was suggested by the guy who helped me mill the slabs).

What should I dry it down to in order to be safe for finishing?

Also, there is some cracking on the ends, was going to do some bowtie splines. Can I do that now, or should I wait until it gets drier? If waiting, how dry before I install the bowties?

THANKS a lot!

Al Weber
12-03-2016, 4:39 PM
I think the worst mistake you can make now is to try to dry them too quickly. All the ideas of putting battens on the slab are good but don't try to hurry the drying. If the moisture levels you specified are correct, it is going to take some months to dry evenly. I won't tell you what to do but if it were my slab all glued up, I'd put battens on it, cover it with something semi-permeable, put a fan nearby to move air over it, and wait it out. Depending on your location, it might even be best to move it outside as the gas heat may tend to dry it too quickly.

I've worked thick slabs of cherry before and always left them outside, covered, ends coated, with good air movement around them until they stabilized. It just takes time. Never buy a slab from that source again. I had a similar situation occur several years ago with rough maple lumber. It was all case hardened and basically unusable. I never went back to that source again.

Jamie Buxton
12-03-2016, 9:59 PM
Yes, bowtie splines now wouldn't hurt. Cracks are just going to pull further open as the wood dries, so putting bowties on should stop that.

John TenEyck
12-04-2016, 6:45 PM
Well at least the wood is below the fiber saturation point, 29%, so the slabs are unlikely to turn into potato chips as they dry down the rest of the way. Nor do you have to be too gentle with their drying. Cherry is a pain, but you can't do too much additional damage at this point. I think it will be fine in your basement, but I wouldn't blow air over it. Clamp some big heavy timbers across it in several places, and flip it over ever week, or lean it along a wall if that's possible and avoid having to flip it. Be prepared to wait many months till it's dry. In the meantime, make your wife something else she's been wanting.

John

John Spitters
12-04-2016, 10:23 PM
I've worked with a lot of slabs, we do our own milling.
I would clamp battens across both ends of the now glued up slab and hope for the best that it won't warp too much as it dries. You will also need to devise some method of keeping the slab from warping into a twist, generally this is done by placing lots of weight over your slab. Place the slab between battens keeping it off the concrete floor in your basement in a cooler area away from any direct heat source, or alternatively outside in a well covered area. Ideally in about a year it will have dropped to apx. 15% moisture, after that you can place the slab into a heated area for the next 6 months plus and expect it to drop to apx. a 10% moisture content, at which point you can complete the finish process.

Scott T Smith
12-05-2016, 8:15 PM
Terry, where are you located?

Several comments. Your kiln operator is at fault - period. The slabs were dried too quickly and improperly for them to be at 21% MC in the core and 8% on the shell. If they had been rained on they would have a higher MC% near the shell as opposed to the core, so this is a drying related issue.

If you paid for "kiln dried" slabs and they are 21% MC in the core, you did not get what you paid for. I would follow back up with the lumberyard and explain that you did not get what you purchased, and let them know that if they don't make it right that you will pursue legal action. If they don't stand behind the product, have an attorney write them a letter. They should figure out pretty quickly that it will cost them a lot more to fight you than to fix the problem.

The slabs calculate out to around 30 board feet each, and based upon the fact that you paid more than $12.00 per board foot for them it is entirely reasonable for you to expect them to make the situation right.

Next, you basically have some 6/4 slabs. The drying rate for 6/4 cherry is around 4.5% - 5% per day. Since the slabs are below 25% MC you are out of the "danger zone" with respect to drying related defects. The lumberyards kiln operator should be able to mix these slabs in with a load of partially dried lumber and finish them off. Since they have been surfaced it would be best if they were placed at the bottom of the kiln stack so as to have the maximum weight on them.

If you don't want to work with the lumberyard, then try to find another kiln operator that can finish the slabs. You will probably pay a hundred bucks or so to put them into a kiln for a few weeks to finish off (most of which would be labor costs on the kiln operators part).

My 2 cents....

Scott

Terry Elvers
12-07-2016, 7:34 AM
Scott;
I am in Leesburg VA (Northern VA).
The kiln operator was no help.
Will not go there again.

I was thinking of clamping angle iron across the bottom of the table. I would put painters tape so it would not mark too bad, but it is on the bottom. Would that be OK?

I will look for another kiln. In the meantime, I am going to do the bowties to stabilize the cracks, and go from there.

Thanks everyone for the help and support.
Terry

Jamie Buxton
12-07-2016, 10:52 AM
Scott;...I was thinking of clamping angle iron across the bottom of the table. I would put painters tape so it would not mark too bad, but it is on the bottom. Would that be OK?....

Why use steel? Steel and water aren't a good mix. You run the danger of getting rust marks on your cherry. Use wood instead.

Terry Elvers
12-07-2016, 11:58 AM
Jamie;
Was thinking steel would be stronger / less cumbersome.
ONLY on the bottom, so any marks would not really be an issue.
Just thinking out loud....

Scott T Smith
12-07-2016, 10:41 PM
Scott;
I am in Leesburg VA (Northern VA).
The kiln operator was no help.
Will not go there again.

I was thinking of clamping angle iron across the bottom of the table. I would put painters tape so it would not mark too bad, but it is on the bottom. Would that be OK?

I will look for another kiln. In the meantime, I am going to do the bowties to stabilize the cracks, and go from there.

Thanks everyone for the help and support.
Terry

The problem with this approach is that the slabs will shrink in width as they dry. I've seen instances where slabs attached to steel w/o slotted holes cupped badly because one side of the slab could shrink an the other side could not.

Plus, you would be amazed how strong wood cells can be. I have a stack of 4" thick slabs that weigh 1000 lbs each, with two 8" thick slabs on top that weigh 2000 lbs apiece. Slabs near the bottom of the stack that are distorting are lifting the entire stack above them.....

If you want to go the steel route (or wood), be sure to slot the holes and snug the fasteners to the point where they are tight but can still slide as the slabs shrink.

Your best bet is to stack, sticker, and weight the stack at 250 psf. Sticker on 16" - 20" centers.

If you want to haul the slabs down to Raleigh, I'll stick them in one of my kilns and finish them off for you.

Terry Elvers
12-08-2016, 9:35 AM
Thanks for the advice, and the kind offer.
Unfortunately, I do not have any way to transport the slabs.
Will just go with what I have, and make sure the steel is slotted.
Thanks
Terry

Bradley Gray
12-09-2016, 12:00 PM
I have several different styles of 4-way clamps in my shop. The best (and least expensive) came in kit form- you supply 2 x 2 lumber.

I would invest in 4 or 5 of these and install them on the top. You can tighten them occasionally as the top dries.

I think the clamps are about $20/ set. You can reuse or sell them.

Ken Parris
12-09-2016, 9:25 PM
I had a similar problem. I bought a 3 1/2" inch thickness and had it split on the bandsaw mill. By the time I got it home there was a one inch gap between the two boards. Mine was wetter on the outside than the inside. I fought those two boards for a good while without success. Finally one night thinking about it I decide to take charge over those boards. The next day I put saw kerfs on three inch centers on the bottom of each board about half way through the thickness. Then added five battens crossway with slotted holes. Then added two more battens that are part of the base support structure. Problem went away. All this was about four years ago and it is still fine.

Ken