Hi,

My friend is seeking general advice as he purchased a solid timber American Oak custom table top with an oil/wax finish and after only a few months he sees some problems developing.

1) cupping / bowing of the top as a whole - in the below photo where a straight/level board has been put on top you can see a gap where the table seems to have bowed/cupped quite a bit



2) Crack in a single board - the photo above shows a crack which has developed in the grain, and below is a close up.
Cracked Grain.jpg


3) Crack along join line - a crack in the join line between boards to make the panel has developed
Cracked Join.jpg


The manufactuerer's response was to quote from their maintenance page:

"All the timber we use in our furniture is pre seasoned and ready for a long hard life. Splits andcracks may develop as it responds to the environment and these are not to be considered afault or flaw and will not compromise the construction of any furniture we make."

I am not an experienced woodworker but thought that issues 1 & 2 might be symptomatic of not letting the wood stabilise or dry out prior to creating the tabletop panel, and that issue 3 should not really happen if glued well in the first place.

I was hoping for some of your experience whether these types of problems would be typically expected and/or acceptable in a commercial product made from this material? For me it seems strange that tables that are decades (or even centuries) old can remain straight and crack free, whereas this is only months old.

Thanks in advance for your help.

The check I’m more likely to understand, depending on the price point of the product.  The more stable you want the wood, the more the product will cost.  If it was a premium product, I would expect them to take reasonable measures to ensure the wood is stable and stand behind it if a problem develops. 

But the glue line failure I’m not so sure about.  If it did dry and shrink after assembly wouldn’t you expect the crack to form adjacent to the glue line and not on it?  My expectation is if it was properly glued and assembled, that long grain glue joint would be stronger than the naked wood fibers next to it.  Is that an incorrect assumption?  Or maybe it’s possible that on board wasn’t completely straight and that part of the joint was weak from the start?

Unacceptable.

If the wood truly was adequately pre-seasoned it wouldn’t split, nor would the joint open.

The check I’m more likely to understand, depending on the price point of the product.

The check developed because the wood wasn't properly dried to between 6 and 8% especially if it developed after purchase. I see this very regularly with low grade products done by people that don't understand how important proper drying is.

  The more stable you want the wood, the more the product will cost.  If it was a premium product, I would expect them to take reasonable measures to ensure the wood is stable and stand behind it if a problem develops. 

The whole design is a perfect example of someone that doesn't understand wood. The price of the product whether premium or not should not be dictated by the stability of the wood, thats a given unless Billy Bob doesn't no shite from shinola.


But the glue line failure I’m not so sure about.  If it did dry and shrink after assembly wouldn’t you expect the crack to form adjacent to the glue line and not on it?  My expectation is if it was properly glued and assembled, that long grain glue joint would be stronger than the naked wood fibers next to it.  Is that an incorrect assumption?  Or maybe it’s possible that on board wasn’t completely straight and that part of the joint was weak from the start?

There is no direct shot of the overall table top to make any direct assumptions of the failure. Improper drying can cause all kinds of distortions, improper joint preparation, inadequate glue or poor clamping could contribute to that failure. Spin the wheel. The disclaimer also says alot about the company and was probably put in place to combat their poor techniques and multiple previous failures of the same sort. Just because they are in business doesn't mean they are any good at what the produce.

[/color]

How are people discerning the method of attachment?  Did I miss a photo?

I don't think people are discerning the method of attachment, they are suggesting that it is something that can affect the top due to wood movement.  More like something to check.

Just like I would like to know what the bottom side finish is like. Another possible reason for the warping.

Seth

I think it is poor work. The check was probably in the board before the table was constructed and not noticed. The ends shrink and crack when they are dried and these cracks need to be cut out before gluing up. It is hard to do when you pay high prices for hardwood but if you have other projects where you can use the cut offs you can minimize the loss of material. The fact that there is only one crack makes me think this was a preexisting condition.

We built nothing but solid wood doors for a about 15 years and depending on how fast the oak was dried we had to cut back the ends by 6 to 18" before the milling process. These cracks can be hard to spot and you need to have good lighting and look closely to see them sometimes. If left they tend to open up later.

The open glue joint is a concern. It is impossible to know what the problem is there. There are a long list of things that could cause this and a lot of them would get worse as time passes.

As has been said it is not possible to see from the photos how the top is attached and not allowing the wood to move could cause problems.

I think both the check and bad glue joint could be repaired  but the rest of the glue lines may be a concern depending on the cause of the problem. The oil wax finish makes this a lot easier.

...
I think both the check and bad glue joint could be repaired  but the rest of the glue lines may be a concern depending on the cause of the problem. The oil wax finish makes this a lot easier.

I use oil/wax finishes a lot.  I live in Colorado, so once the wood gets down to about 6% moisture content, it stays there.  However, I have done oil/wax finished boards for high moisture applications like bathroom counter tops.  For those applications, I rub in a lot of coats (15-20) to isolate the wood from the moisture as much as possible.  In general, I'm a bit scared of oil finishes when there is a lot of change in relative humidity.


I know there are other factors involved oil finishes, like the % of solids in the oil, whether the finish is rubbed with wet/dry sandpaper so that wood dust fills the grain, and so on.  I generally mix some poly varnish in with the oil and wet sand with 600 grit or higher.  If I want a better finish, I rub in more coats and sand to finer grits.


If this is a commercially produced table, I'd be wiling to bet that the oil finish was applied with just the final look in mind.  As @Oldwood mentioned, an oil finish is (relatively) easy to repair, although you still have a account for changes in the color of the wood over time due to UV, sanding and buffing patterns, and so on.


As others have mentioned, I'd be surprised if these issues didn't get worse over time, particularly if you have big seasonal swings in relatively humidity, either due to natural weather patterns or to heating/cooling systems that only kick in during certain times of the year.  In my experience, day/night swings in humidity don't affect wood much.


As an aside, I'd be interested in a thread on how people have fine-tuned their oil finishing techniques over the years, either with specific products or specific techniques.

how much did your friend pay for this?

i'd fix and accept whatever wood shrinkage and cracks, but their own glue line failed in #3 - that is not acceptable, that is literally all on them and they failed gluing two boards together

Ditto gluing the dominoes. Easy enough even if you think you don't need them other than for alignment. It only takes a second.

Thanks all again for your replies. My mate is also watching this thread  , so hopefully he can get some ideas here.

I had also asked about the base prior to posting and here are the photos for those who are as curious as I am:




I can't tell if the holes for the bolts into the top are elongated or oversized to allow for movement, but he had been advised to "not tighten too much" (which doesn't really say much at all).

From looking at the photos it looks like there is no accommodation for wood movement. I would put one or two fasteners in the middle of the panel that have no slots to fix the panel and route slots for the other bolts and washers.

It does not look to me from the photos that this fastening method is the cause of the check or glue joint failure but it could be contributing to the bowing. 

Definitely would prefer elongation as opposed to just oversized holes for that dimension of top.

Definitely would prefer elongation as opposed to just oversized holes for that dimension of top.

I have used the Domino to bore elongated holes for wood movement or adjustment.

Seth