# Outdoor wood table top help!



## Jordan7990 (Sep 26, 2020)

I have a hickory table top that a client wanted me to finish back in April. It was bare wood so I coated it with “Seal coat nano sealer” and 3 coats of “General finishes 450” on the top and bottom. Well went back today and the table top was warped and definitely looked like it was holding moisture. That coating process was a failure. Anyway I have the table top now and currently sanding it back to bare. Any suggestions on a top coat that will be durable outdoors, Also won’t let the wood warp and bend? It’s covered under a screen porch and gets little to no rain hitting it. 

Thanks for your help!


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## vwbowman (May 15, 2017)

I have never heard of coating that will prevent wood from warping or bending! My customers that do live edge u-channel metal strips, screwed into the bottom of the the slab about every 6". I have also learned that most do not like to tables less than 2" thick due to the warping issues on thinner slabs.

When you say you sealed it, did you do all sides? Bottom included? The Exterior 450 is a good choice as it is designed to all moisture to escape; the other product would be three coats of ProLux (formally SIKKENS) CETOL 1.


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## PPD (Mar 19, 2018)

Wood is an organic material, I don’t think any company would claim their material could prevent warping due to moisture absorption. Even the best outdoor coatings will require an upkeep schedule they need to commit to in order to keep it in good condition. 

To stop all moisture from entering you might be looking at something like encapsulating all the fibers in a resin epoxy...but even that will fail over time & horrible to try and remove when it does (not to mention the lack of UV protection & yellowing).


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## IKnowNothing (Oct 15, 2020)

vwbowman said:


> I have never heard of coating that will prevent wood from warping or bending! My customers that do live edge u-channel metal strips, screwed into the bottom of the the slab about every 6". I have also learned that most do not like to tables less than 2" thick due to the warping issues on thinner slabs.
> 
> When you say you sealed it, did you do all sides? Bottom included? The Exterior 450 is a good choice as it is designed to all moisture to escape; the other product would be three coats of ProLux (formally SIKKENS) CETOL 1.





Jordan7990 said:


> I have a hickory table top that a client wanted me to finish back in April. It was bare wood so I coated it with “Seal coat nano sealer” and 3 coats of “General finishes 450” on the top and bottom. Well went back today and the table top was warped and definitely looked like it was holding moisture. That coating process was a failure. Anyway I have the table top now and currently sanding it back to bare. Any suggestions on a top coat that will be durable outdoors, Also won’t let the wood warp and bend? It’s covered under a screen porch and gets little to no rain hitting it.
> 
> Thanks for your help!


Even tho the table was under a screed porch and no rain hitting it - is it possible that the wood had some moisture trapped in it when you applied the nano sealer and the General Finishes 450? 

*Also GF is suggesting this:*
"How Soon Can I Put My Project Outdoors After Finishing with General Finishes Exterior 450?"
We recommend waiting 5-6 days to let the finish cure a bit before putting outdoors. 
The finish will continue to harden for approximately 20-21 days.
https://generalfinishes.com/wood-fi...ains-oils/exterior-450-water-based-wood-stain

Was the table left outside?
Maybe there was a 'chemical conflict' between Nano Sealer and GF, or maybe if the table was left outside the drying and curing process 
of those two products wasn't happening in a proper way resulting in warping.

*Also this:*
Durability.
It is the strongest wood type that we offer. 
Due to the density of this wood, it can be prone to warping and cracking and does require even more attention to the room's humidity level. 
https://www.amishtables.com/pages/hickory

I know it sucks since sounds like you were using high quality products trying to do high quality job for the customer.
I feel your stress.
Both of them, the Nano Sealer and the GF are regarded as high quality products.

General Finishes 450 STAIN. Technical Data Sheet: 
https://generalfinishes.com/sites/d...20-03-Exterior-450-Stain-General-Finishes.pdf

General Finishes-450 EXTERIOR WATER BASED TOPCOAT:
https://generalfinishes.com/sites/d...-03-Exterior-450-Topcoat-General-Finishes.pdf
*Note**
System Recommendations: Use without a sealer. At least 3 total coats of finish are recommended. 

Strange occurrence.
How bad is the warp.
Can you post some pictures.

Perhaps consider contacting both manufacturers (Nano Seal & GF) and ask them what they think about it, and what they can advise you to do to fix it.

I wouldn't apply different product before finding out what was the cause of this mishap.

.


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## Redux (Oct 27, 2018)

First off, the hickories are ranked amongst some of least dimensionally stable domestic wood species and are prone to excessive movement and warping when subjected to abrupt or drastic moisture content swings when exposed to moisture or when drying. IMO, hickory just isn’t the best choice for an exterior solid wood tabletop, even less so if flatsawn. 

Regardless of species, improper fabrication can be a major contributing factor to warping. With solid flatsawn tabletop panel glue-ups, before finishing, I’ll check the end grains to see if the fabricator alternated the growth rings at each board which should be bark down/bark up at every board transition. By alternating growth rings each board will warp or cup in a different direction, offsetting and reducing the chances for the entire top to warp in one direction across the entire surface. I’ll often bring it to the attention of the client if not done correctly just to CMA.

Edit: it’s sometimes a good idea to let the wood acclimate and and allow it to reach equilibrium moisture content with the outdoors before finishing. The warping could be due to the wood being too dry when first finished and not being in equilibrium with the exterior environment.


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## Jordan7990 (Sep 26, 2020)

vwbowman said:


> I have never heard of coating that will prevent wood from warping or bending! My customers that do live edge u-channel metal strips, screwed into the bottom of the the slab about every 6". I have also learned that most do not like to tables less than 2" thick due to the warping issues on thinner slabs.
> 
> When you say you sealed it, did you do all sides? Bottom included? The Exterior 450 is a good choice as it is designed to all moisture to escape; the other product would be three coats of ProLux (formally SIKKENS) CETOL 1.





vwbowman said:


> I have never heard of coating that will prevent wood from warping or bending! My customers that do live edge u-channel metal strips, screwed into the bottom of the the slab about every 6". I have also learned that most do not like to tables less than 2" thick due to the warping issues on thinner slabs.
> 
> When you say you sealed it, did you do all sides? Bottom included? The Exterior 450 is a good choice as it is designed to all moisture to escape; the other product would be three coats of ProLux (formally SIKKENS) CETOL 1.


Thanks for the suggestion everyone. Gonna give this another shot.


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## Jordan7990 (Sep 26, 2020)

I sealed all six sides with the nano sealer and the 450. My brother In law suggests adding metal angle iron on the bottom. He had 100 plus tables he built do this. He said it’s because any material under a 1 1/2” will bend and flex no matter what you do.


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## stelzerpaintinginc. (May 9, 2012)

Did you by chance measure the moisture content of the wood before initial application? Assuming you brought it in from outside to coat it inside? Was there a drastic temperature & humidity difference between outside & inside? How soon did you apply your first coat after moving it inside? Have you noticed any new cracks or checking? 

As Redux mentioned, the initial construction could be less than desirable, which means you might have issues with warping even if you do everything else right, especially on less dimensionally stable woods like Hickory. With the exception of American Beech, I don't know of a less dimensionally stable wood.


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## Redux (Oct 27, 2018)

Sliding dovetail joint:
In order to minimize the chances for warping when fabricating tabletops, I’ve utilize sliding dovetail joints on the tabletop undersides. I’d router cross-grain dovetail keyways into the tabletop undersides utilizing a sliding shaper w/outrigger plus a router spindle & bit. I’d then fabricate dovetail keys, sliding the keys into the keyways, also alternating the growth ring orientations on the glue-ups. The keys when slid into the keyways inhibited warping by providing multiple table base attachment points across the entire width which reinforced the top, also allowing for seasonal movement due to the bases being fastened to the keys while the tops remained floating. They keyways also provided stress relief. Never had a tabletop warp, the wood split, or the glue joints fail by using the described method. A bit of overkill by any woodworking standards but it was very effective.

Also when finishing tabletops with waterborne coatings, I’d wet down the opposing side with deionized water and flip the top after every coat rather than doing all the coatings on one side first. The described method also inhibits warping, at least during the finishing and drying.

What you’re seeing in the photo is the underside of a tabletop I fabricated with the sliding dovetail keys running cross-grain.


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