How Climate Affects Veneer

By Bernie Bottens | Posted: 04/04/2013 9:26PM

 

Bernie Bottens how to finish wood We have been discussing the subject of veneer checking these past weeks. I hope that you will look back on the previous articles in this series to understand the direction that I am going and to see how what I have said impacts this week’s edition.

Referring back to last week’s installment, what are the chances of something happening to the veneer as the result of expansion or contraction from temperature and humidity fluctuations?

1. The veneer traveled rapidly from the Midwest states to Portland, Oregon, back to the dry coldness of the west and then on to sunny, ultra dry Las Vegas in short order.

2. Due to the schedule, there was no time given to acclimate the veneer to any of its new environments at any point in its journey.

3. The panels used as substrate did not follow the same route as the veneer. Whatever expansion or contraction occurred within those panels was the result of environmental changes between Portland to Vegas. Change, though small, will occur.

I’ve written this imaginary story for the purpose of illustrating what might happen. In truth, this story has some basis in fact. But, as I often do, I change things slightly. My Central Oregon clients, mentioned in the initial installment of this article, were mentioned for a reason.

Their stories were those of veneer that had been subjected to rapid climate change. There are also resemblances to other shops in the northwest that specialize in work such as described here. For them, this story may be uncomfortably real. I would be remiss if I did not hold up that famous quote from the true crime series, Dragnet. “The story you are about to hear is true. Only the names have been changed to protect the innocent.”

The best thing that you could do is to allow sheets of veneer to acclimate thoroughly before they are glued to the substrate. Let the expansion and contraction happen before it’s glued down.

Rule #1 Acclimate, acclimate, acclimate!
That being said, I have seen all too often that the schedule and Murphy’s laws impact the needs of the job as it did here. As a result, things that really need to be done don’t get to be done. The effects can be minimal or they can be painfully obvious later on. Thus...

Rule #2 One can only successfully dodge bullets for so long.
You will know sooner or later how successful you were at making your way through this complicated process. Humidity cycles and temperature cycles will play out regardless. Wood will react to those cycles and only then you will know whether the bullet found its mark or not.

In conclusion, I was sitting at my banker’s desk the other day. It was a very nice veneered red oak desk. When my banker stepped away to go do something I found myself doing what Bernie often does when Bernie, the woodworker, has nothing else to do. I was looking at this beautiful desk with the eye of a builder and finisher. It was then that I spotted an area in the corner of the desktop that contained some minor veneer checking.

I have no idea what caused it. I have no idea of where this desk has been since it was built or what it has experienced since then. All I know is that something caused that veneer to check.

Likewise, PianoMan, from my installment #1, has no way of knowing what that 1896 Steinway has seen in its long life. All he sees are the results. Was the veneer defective in some way at application? Who knows? But Steinway being Steinway, I would doubt that. I suspect that something environmentally significant yet lost in time befell that instrument somewhere in its long history and caused the veneer to check badly.

In the end, when you begin a project requiring that you fabricate veneered panels.

1. Acclimate, acclimate, acclimate.

2. Think long and hard about which gluing process you use to bond the veneer to the substrate. It must be firmly bonded.

3. As much as possible, keep Mr. Murphy and his rules away from your project!

Until next time…spray on!


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About the Author

Bernie Bottens

Bernie Bottens (WoodworkingNetwork.com/blogs)writes and teaches on the subject of wood and wood finishing in industrial woodworking. He and his wife, Carol, live in Vancouver, WA. Bernie has been teaching wood finishing to shop owners, shop foremen, spray technicians and finishers all over Oregon, southwest Washington, and northern California for the past 9 years. Prior to that, he owned his own cabinet shop. His shop credentials include apprenticing and becoming a journeyman exhibit builder. Before that he taught in the public schools for 20 years. Bernie is the owner of Kapellmeister Enterprises, Inc. and Kap Coatings Consulting. Reach him at kapenterprises@msn.com.

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