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Live Slab Dining Table/Epoxy question

by BGWood
posted 01-17-2019 04:01 PM


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60 replies so far

View LittleShaver's profile

LittleShaver

514 posts in 949 days


#1 posted 01-17-2019 04:19 PM

The wood is still going to try to move, I would suggest skipping the epoxy and using slotted holes in the C Channel with screws into the wood to keep things flat and allow for movement. You may also want to extend your slots a little to give the slab room to shrink. No one sees the underside of a table, so give the slab some wiggle room.

-- Sawdust Maker

View Snipes's profile

Snipes

392 posts in 2575 days


#2 posted 01-17-2019 04:21 PM

the wood needs to move.. it is alive man. i don’t believe the epoxy would allow for expansion and contraction, also the metal channel should not fit to tight in length.

-- if it is to be it is up to me

View Manitario's profile

Manitario

2747 posts in 3213 days


#3 posted 01-17-2019 04:24 PM

I agree with the above comment. You can’t (and shouldn’t try) to prevent wood movement, if you do it guarantees that the top will crack or split at some point. If the slab is properly dried and seasoned, you should get very, very little “buckle or twist” due to seasonal movement. I regularly work with large slabs and have never had anything twist out of shape once properly dried.

-- Sometimes the creative process requires foul language. -- Charles Neil

View Aj2's profile

Aj2

2129 posts in 2128 days


#4 posted 01-17-2019 04:30 PM

Is that epoxy in there yikes. It looks to be a very beautiful looking slab,certainly a presentation piece. So I would dig out that black stuff and pray for forgiveness.
Even go as far as to add wood back in orientated in the proper direction. “With the grain”.
Good luck

-- Aj

View BGWood's profile

BGWood

36 posts in 95 days


#5 posted 01-17-2019 04:31 PM

The channels have been slotted 1.25’’ in length to allow movement and the ends all have 1/4’’ to also allow movement.

the slabs were kiln dried and acclimated to the humidity and moisture in the home.

-- Brian, Pennsylvania

View BGWood's profile

BGWood

36 posts in 95 days


#6 posted 01-17-2019 04:34 PM

Appreciate the feed back so far…. i agree with all of you guy’s comments….. just am looking for additional input to support what I already thought would not be worthwhile to do and throw away money on epoxy if not needed.

i used 5/8’’ threaded brass inserts (16 total) to anchor the iron into place. (just have not anchored them down until I sand and Waterlox the underside

-- Brian, Pennsylvania

View BGWood's profile

BGWood

36 posts in 95 days


#7 posted 01-17-2019 04:35 PM

there is no epoxy in the slots at all at this point those are the painted steel channels i put in to test fit everything

-- Brian, Pennsylvania

View Snipes's profile

Snipes

392 posts in 2575 days


#8 posted 01-17-2019 04:35 PM

Sounds like your good to go. get building so we can see the finished product…

-- if it is to be it is up to me

View Aj2's profile

Aj2

2129 posts in 2128 days


#9 posted 01-17-2019 07:22 PM

Ok I get it now . I’ve never seen that before. Please share the show side with us .
I nothing further to add this is uncharted territory for me I bow out.
Good Luck

-- Aj

View LiveEdge's profile

LiveEdge

600 posts in 1950 days


#10 posted 01-18-2019 08:15 PM

How buckled and twisted was it before you planed it down? The initial drying is going to be the worst stress as the wood goes from 20% to 10% (or whatever). The drying then reveals the natural inclination of how the wood wants to be. The natural breathing a wood can do from season to season is going to be a much smaller moisture difference. Since the piece is a slab we don’t have to worry about joint lines. In my opinion the wood will breathe in the same manner as it did when first dried.

TL;DR: If you had a lot of planing to do on this piece due to buckle or twist, then you might need to be worried. If it wasn’t a big job, I think you will have a very stable piece of wood.

View BGWood's profile

BGWood

36 posts in 95 days


#11 posted 01-18-2019 08:36 PM

The wood was naturally pretty true and I had the moisture content down to 8-9% in it all over before moving to working with it. It only needed sanded on a wide belt sander and it took down all my epoxy fill in spots and levels any ridges in the wood. The wood has a slight cup overall but is very minimal. The bars are to help with keeping the cup from ever being an issue.

-- Brian, Pennsylvania

View LiveEdge's profile

LiveEdge

600 posts in 1950 days


#12 posted 01-18-2019 09:39 PM

I’m not an expert (though I’ve worked with slabs, see projects), but I bet you are going to be just fine. I like the idea of using elliptical holes to allow for natural expansion like a breadboard.

View BGWood's profile

BGWood

36 posts in 95 days


#13 posted 01-19-2019 10:42 PM

Here is the underside after one coat of Waterlox and the c-channel now in place

-- Brian, Pennsylvania

View BGWood's profile

BGWood

36 posts in 95 days


#14 posted 01-26-2019 09:00 PM

Here’s after the final waterlox application for the underside

-- Brian, Pennsylvania

View avsmusic1's profile

avsmusic1

376 posts in 1015 days


#15 posted 01-27-2019 12:00 AM

Man that’s some gorgeous wood you picked there

Share a pic of the other side please- if the grain on the underside is this nice I’d love to see the side you picked as the top

View BGWood's profile

BGWood

36 posts in 95 days


#16 posted 01-27-2019 12:22 AM

These are my plans for the legs/base and I’m working on those now The top plate will be 3/16 or 1/4 steel (as well as the foot plate). The rest is 14 gauge 2”x2” steel bent into tubes.

Should have that done in a few weeks and powdercoated

I’m an anxious to flip the top over and get it finished as well. I’m giving the waterlox plenty of time to dry before each coat and before flipping over and finishing the top

-- Brian, Pennsylvania

View BGWood's profile

BGWood

36 posts in 95 days


#17 posted 01-27-2019 06:16 PM

Interesting twist in the plot folks.

Before the channel and waterlox was added to the underside of the table in the pics above… the board laid flat and was true within1/16-1/8”(acceptable enough for me)

After applying the coats of waterlox and the channels were installed. Ironically the table began to cup beyond what it was previously

It’s now closer to 3/16” or 1/4” on the one end and about 1/8” still on the middle and other end….

Could the waterlox have affected this ?!

I flipped the table and have it in a mild clamped position for now until I decide the next course of action…

1). Spray it with water and let it soak up moisture and let it clamp a little each day for the next few weeks before putting back into dehumidifier kiln?

2). Clamp and apply dry heat?

3). Suggestions?

Kinda puzzled since it was flat and dried prior to the waterlox

-- Brian, Pennsylvania

View Manitario's profile

Manitario

2747 posts in 3213 days


#18 posted 01-27-2019 06:40 PM

Is the cupping noticeable without a straightedge ie. will you or others see the cupping? If not, I wouldn’t worry about it. 1/8-1/4” cupping over a large, wide slab is not a big deal and if it doesn’t affect the way it looks, I’d leave it alone. A lot of historical pieces have similar amounts of cupping that no-one notices unless they have a straightedge. The wood is going to move how it wants to move….

-- Sometimes the creative process requires foul language. -- Charles Neil

View BGWood's profile

BGWood

36 posts in 95 days


#19 posted 01-27-2019 06:46 PM

True and I agree with you. My concern is forecasting the results when I attach the steel base/legs. I’m using threaded anchors(8) per top plate and the plate is 8” wide and 30” long The steel will be 1/4” thick. My thoughts/ hopes are that when I go to add the top plate and then anchor it will help draw some of the cup out of it and help to reinforce the c channels that already are in place

Dont want the table to draw the legs up and create a wobble affect (ideally)

-- Brian, Pennsylvania

View Snipes's profile

Snipes

392 posts in 2575 days


#20 posted 01-27-2019 07:49 PM

Yes applying finish to one side can definitely cause this. Or it just wasn’t as dry as you thought and now one side is sealed and the other side is drying causing the cup. i like to do one side then flip and do the other side before putting any more coats on.
sometimes drying one side and moisture to the other will work, but not always. I have had luck with smaller pieces by putting next to my wood stove and it pulls the cup out, but have not tried anything this big.

in my case having to slightly adjust legs to floor is not that uncommon

-- if it is to be it is up to me

View gcfaman's profile

gcfaman

14 posts in 109 days


#21 posted 01-28-2019 03:02 AM

It looks great from the bottom (a view I frequently see) . You have thought it through and done your best. If cracks occur, tell people you could have used Formica. Wood lives even after being tooled.

-- George Cherry Hill

View gcfaman's profile

gcfaman

14 posts in 109 days


#22 posted 01-28-2019 03:05 AM

I forgot to say – Great top.

Lucky Wife!!

-- George Cherry Hill

View Logboy's profile

Logboy

75 posts in 3560 days


#23 posted 01-29-2019 01:12 AM

Your slab is warping because its not dry. Its that simple. If it was 9% at the surface it could be as high as 12% in the middle, nowhere near dry enough. Slabs only warp because theyre drying and the cells are shrinking. If you air dried that slab instead of kiln drying its going to move a lot more seasonally.

Your slab is clearly not at equilibrium moisture (with the humidity in the air) which is why its warping. If you coated one side and not the other then its going to dry on one side and not the other. So you have two options. Hurry up and coat the topside, or sand off the bottom. Personally I’d sand the bottom off and quit pissing with it until its finally dry. Given the thin nature of your slab youre just going to be chasing your tail trying to keep it flat. If it keeps warping you might have to rip it into strips and glue it back together, otherwise youll have to surface the thing down to nothing to get the warp out. I never go thinner than 8/4 finished thickness on my live edge tables. Its usually closer to 9/4 or 10/4.

Oh and if put epoxy in with those braces youll just constrain the width and either break the screws or crack your slab.

View BGWood's profile

BGWood

36 posts in 95 days


#24 posted 01-29-2019 01:27 AM

Log,

The slabs were kiln dried first of all, and have had two dehumidifiers running in the basement the entire time they have been indoors, along with ample cross ventilation.

There’s no epoxy in the channels (read prior post)

I pulled plug samples from the underside and tested it numerous places and numerous times and it was consistent with the same MC rating.

That’s great you could find 10/4 or 9/4 thickness. I could not find any of that in my region.

Don’t need to be rude nor condescending about what you’d do.

I respectifully sought suggestions.

And since my last post I was able to resolve my issue with it having to sand or cut and kerfs and wedge it.

-- Brian, Pennsylvania

View Logboy's profile

Logboy

75 posts in 3560 days


#25 posted 01-29-2019 01:44 AM

What moisture meter are you using? None of them are 100% accurate including my $500 setup. They measure resistance in wood not the actual moisture content. If the wood is warping its literally telling you its not dry, especially as fast as yours is warping. I start with the moisture meter and then go on experience from there. If youre using something like a Mini lingo, just throw it away. They can be as much as 5% off and are not reliable.

I have access to 12/4 wood because I cut and kiln dry all the wood I use. I build live edge tables for a living. I just gave you advice based on years of experience for nothing. If youre going to get bent out of shape when people with more knowledge give you advice, then don’t ask for it.

View BGWood's profile

BGWood

36 posts in 95 days


#26 posted 01-29-2019 01:58 AM

I appreciate insight and advice but there’s no need to come across as rude to a fellow woodworker.
I know how a moisture meter works and am familiar with them and I have a very good quality meter. I checked it after they were Kiln dried and I know the slabs were under 9%

And that’s great that’s your line of work and your access to that type of stock. I simply do not and am doing as best as possible with what is available in my region of PA

And just so I’m 100% clear, I’ve been nothing but open and considerate to everyone that replies to help me out. You don’t need to defend your line of work. Again, I appreciate suggestions..

To reiterate…
My slabs were dry and flat. As my post said. Only after the tung oil did it cup.

The steel channels I put in did exactly what they were supposed to do and pull the table back flat, presumably after the tung oil carrier system evaporated and the wood is dry and tung oil is curing. It’s straightening itself out naturally

-- Brian, Pennsylvania

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Snipes

392 posts in 2575 days


#27 posted 01-29-2019 03:17 AM

wood doesn’t only warp because it’s drying, it can also warp taking on moisture….

-- if it is to be it is up to me

View Logboy's profile

Logboy

75 posts in 3560 days


#28 posted 01-29-2019 07:25 AM

Under 9% doesn’t mean it’s dry and at equilibrium, it just means you’re closer than air dried. Do you ever wonder where those numbers come from? It has to do with the temperature and humidity. We kiln dry wood from 6 to 8% moisture because that usually matches the interior conditions of our homes (30-50% humidity at 70 degrees). This time of year it’s super dry. My home and woodshop right now are 20% humidity or lower which actually gives them a moisture content in the 4% range.

If you’re heating your home at all, and you have a dehumidifier running, it’s going to be crazy dry. In which case, that would explain why your slabs are not at equilibrium which is why your table is warping, which is what I’ve been trying to tell you all along. Putting giant steel bars under your table doesn’t fix the underlying problem that they aren’t dry. That’s like patching a flat tire on your car when you’re in a parking lot full of nails. You haven’t fixed the underlying problem.

I finished up two walnut tables this week. Due to all the epoxy detail work they’ve been in my shop the last eight weeks. I checked both of them tonight with a straight edge. The little 4 footer is dead flat. The 8 footer has a 1/16” cup on one end, the rest of it is flat. Neither one have any sort of steel plates or reinforcement underneath keeping them flat. Like I’ve been saying, dry wood doesn’t warp. If it warps, it’s not dry. Yes it’s possible for wood to warp due to an increase in moisture, but 99% of the time it’s because it’s drying. Very few kiln operators over dry, most don’t dry enough because they want to turn product over as fast as possible. Thats why its so important to make sure your woodshop is at the right humidity and you let your wood acclimate before you start your project.

View Logboy's profile

Logboy

75 posts in 3560 days


#29 posted 01-29-2019 07:50 AM

Btw, there is a way to “freeze” a wood slab in place regardless of moisture content to keep it from warping. Do an epoxy pour finish top and bottom. Its an impenetrable barrier so the slab has no contact with the air and therefore has no seasonal movement. But epoxy is labor intensive to do right, and good stuff isn’t cheap. And you still have to topcoat it with a lacquer or conversion varnish like I do because it doesn’t have a UV inhibitor and turns yellow over time.

Every one of us who build live edge furniture have had to deal with unexpected warping. The answer is always the same. Either throw it back in the kiln, or leave it alone in the shop until its at equilibrium and stops moving. Unfortunately there’s never a quick fix to the problem.

View BGWood's profile

BGWood

36 posts in 95 days


#30 posted 01-29-2019 10:39 AM

As I said… my problem was resolved

-- Brian, Pennsylvania

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BGWood

36 posts in 95 days


#31 posted 01-29-2019 11:55 AM

but thanks for adding your knowledge to the discussion

-- Brian, Pennsylvania

View Snipes's profile

Snipes

392 posts in 2575 days


#32 posted 01-29-2019 01:49 PM

Logboy thanks for the breakdown. Nice slabs- what do you use for finish, are these sold already?
dealing with moisture and warping can be unpredictable and frustrating.
Brian I think you’ve thought through most the problems and it’s looking great/ as long as theres room to move by that steel you will be fine. excited to see finished product.

-- if it is to be it is up to me

View BGWood's profile

BGWood

36 posts in 95 days


#33 posted 01-31-2019 04:30 PM


After it straightened itself out… here is first coat of waterlox so you guys can see the topside grain! Makes me smile to see it :)

-- Brian, Pennsylvania

View Lazyman's profile

Lazyman

3226 posts in 1717 days


#34 posted 01-31-2019 05:19 PM

Beautiful! Nicely done.
For future reference, since cheap moisture meters are never 100% accurate, one way to get a better (another anyway) reading on the actual moisture content is that take an off cut, weigh it (I use a kitchen scale) and then microwave it on low for a minute or two, let it cool off and weigh it again. Repeat this until it stops losing weight. You can use the beginning and ending weight to estimate a beginning moisture content. Of course since off cuts are often end grain and end grain loses moisture faster than side grain, they will likely be lower than the middle of the board . An offcut from the middle may give a better reading but either way it may give you an better idea of the actual moisture content.

One more thought…I wonder if the dados in the underside for the braces, since they expose endgrain in the middle, could actually cause more rapid, uneven or extreme moisture fluctuations? Something to think about.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View BGWood's profile

BGWood

36 posts in 95 days


#35 posted 01-31-2019 05:29 PM

Lazy,

I had contemplated that when I did make the cuts… so I waterloxed under the c channels and let it cure before I installed the channels. That should slow down/lock that issue away!

But thanks for that consideration.

-- Brian, Pennsylvania

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avsmusic1

376 posts in 1015 days


#36 posted 01-31-2019 07:46 PM

Beautiful stuff Brian
Is that curl on the bottom left – it’s so long it almost looked like milling marks at first glance.

I bet this is just jaw dropping in person

View BGWood's profile

BGWood

36 posts in 95 days


#37 posted 01-31-2019 07:50 PM

Those are natural marking in the wood that give it a tiger stripe affect. The wood was sanded smooth before finishing

-- Brian, Pennsylvania

View Snipes's profile

Snipes

392 posts in 2575 days


#38 posted 02-01-2019 12:33 AM

Beautiful!! That is some nice!!! now i want to see the base

-- if it is to be it is up to me

View BGWood's profile

BGWood

36 posts in 95 days


#39 posted 02-01-2019 01:13 AM

Here’s where I’m at on the base…. almost there

-- Brian, Pennsylvania

View Snipes's profile

Snipes

392 posts in 2575 days


#40 posted 02-01-2019 03:09 PM

You do nice work… I wonder if you will need a stretcher from side to side?

-- if it is to be it is up to me

View LiveEdge's profile

LiveEdge

600 posts in 1950 days


#41 posted 02-01-2019 05:04 PM

Are you going to use oblong holes to attach the legs to the slab? You legs are different than many steel legs in that they are joined which will not allow natural movement.

View BGWood's profile

BGWood

36 posts in 95 days


#42 posted 02-01-2019 05:10 PM

Yes. All the holes for attachment are slotted for movement

-- Brian, Pennsylvania

View BGWood's profile

BGWood

36 posts in 95 days


#43 posted 02-01-2019 05:12 PM

If you look closely at the images of the base you can see they are elongated. They are 1.25” in length and wider than my bolt to allow for vertical and lateral movement in the wood

-- Brian, Pennsylvania

View BGWood's profile

BGWood

36 posts in 95 days


#44 posted 02-22-2019 12:14 AM

Took me a little longer than anticipated but legs are almost done and reading for last process of connecting top to legs!

-- Brian, Pennsylvania

View BGWood's profile

BGWood

36 posts in 95 days


#45 posted 02-22-2019 12:14 AM

-- Brian, Pennsylvania

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Snipes

392 posts in 2575 days


#46 posted 02-22-2019 12:25 AM

( ͡° ͜ʖ ͡°)

-- if it is to be it is up to me

View BGWood's profile

BGWood

36 posts in 95 days


#47 posted 03-05-2019 02:04 AM

Home stretch folks….

gonna work on the threaded inserts this week hopefully and put rubber padding on the base plate feet and finally get it upstairs!

-- Brian, Pennsylvania

View Snipes's profile

Snipes

392 posts in 2575 days


#48 posted 03-05-2019 03:08 AM

Great, should fit in my truck. Do you want me to pull around the back?

-- if it is to be it is up to me

View Aj2's profile

Aj2

2129 posts in 2128 days


#49 posted 03-05-2019 04:10 AM

Awww your killing me Brian. I thought this was the finale the wrap up the mic drop.
Darn teaser :)

-- Aj

View BGWood's profile

BGWood

36 posts in 95 days


#50 posted 03-08-2019 03:19 AM

It’s going upstairs this weekend and chairs are being delivered this weekend/early next week

Stay tuned folks

I’m as excited as y’all are

-- Brian, Pennsylvania

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