| Author |
Message |
J. Peter Jordan
Senior Member
Username: jpjordan
Post Number: 622
Registered: 05-2004
| | Posted on Saturday, October 12, 2013 - 02:59 pm: |    |
This last week, I attended the AWI annual convention in Orlando. While I was there, one of the woodworkers raised an issue that may have been discussed here before: compatibality between wood composite panels manufactured with resins that contain no added urea formaldehyde and the adhesives used to adhere wood veneers. There are issues with delamination and issues with discoloration of wood veneers.
Has anyone encountered this and if so, did you find a satisfactory solution? |
Richard L Matteo, AIA, CSI, CCS
Senior Member
Username: rlmat
Post Number: 628
Registered: 10-2003
| | Posted on Monday, October 14, 2013 - 12:46 pm: | |
I've specified a lot of decorative laminate adhered to MDF board. This is the first I've heard of this being an issue. Is it just the natural wood veneers that are at issue? |
J. Peter Jordan
Senior Member
Username: jpjordan
Post Number: 625
Registered: 05-2004
| | Posted on Monday, October 14, 2013 - 01:12 pm: | |
My understanding is that it is only with natural wood veneers and only "no urea formaldehyde added" panel and adhesive products. |
ken hercenberg
Senior Member
Username: khercenberg
Post Number: 624
Registered: 12-2006
| | Posted on Monday, October 14, 2013 - 02:03 pm: | |
I've had a lot of discussions about the correct adhesives to use with NAUF panels and wood veneers but no consensus at this point. Oddly, most shops seem to want to use formaldehyde based adhesives. Discussions I had with LEED consultants has indicated that this is still acceptable despite UF content in the adhesive. How that can be acceptable, I don't know. There still has to be some outgassing but I guess the levels are kept low enough to pass after the building is flushed out.
Are you finding the problem to be more prevalent with shop finished panels or field finished panels? |
J. Peter Jordan
Senior Member
Username: jpjordan
Post Number: 626
Registered: 05-2004
| | Posted on Monday, October 14, 2013 - 02:06 pm: | |
I almost always specify shop-finished woodwork. It sounds like your LEED consultants are very reasonable. I would really prefer that such products pass the California chamber test used in LEED for Schools. |
John Bunzick, CCS, CCCA, LEED AP
Senior Member
Username: bunzick
Post Number: 1539
Registered: 03-2002
| | Posted on Monday, October 14, 2013 - 04:16 pm: | |
I thought that the most common woodworking glues were polyvinyl acetates, so I did a little research which seems to confirm that. Urethanes are also used. PVAs seem to often pass the small chamber test for emissions, but they may not be 100 percent free of formaldehyde. Keep in mind that wood itself has formaldehyde in it. So, what is the goal? I don't know about actual formaldehyde adhesives used in woodworking, not to say the don't exist.
Also, I haven't heard about the compatibility issue, but I have never heard about any failures in the many projects where this was specified. I suppose there are some shops that have certain procedures that they didn't (or wouldn't) adapt to different materials. |
ken hercenberg
Senior Member
Username: khercenberg
Post Number: 625
Registered: 12-2006
| | Posted on Monday, October 14, 2013 - 04:47 pm: | |
I've used PVA for plam but not wood veneer. The water-based adhesives seem to be unpopular with the woodwork folks I've worked with, probably because they take more time. I don't know if they would have any affect on finishing. I don't know if the panels being NAUF would make a difference in this; could the problem be the change in adhesives?
I wonder if some of the problems may be that the finishers didn't allow the extra time needed for the adhesives to properly flash or to fully cure. I would imagine either condition would result in finish failure.
Are these project certified by a woodworking organization such as AWI? That would certainly give you the ability to bring in someone who may have good hands-on experience in dealing with this sort of issue. |
Steve Taylor
Senior Member
Username: steveatwi
Post Number: 63
Registered: 07-2008
| | Posted on Tuesday, October 15, 2013 - 07:34 pm: | |
We have seen problems with fire retardant NAUF panels. If anyone knows what causes the discoloration they aren't telling. I believe that it could be a reaction with the glue, but is more likely a reaction of the fire retardant chemicals in the core with the aromatics in the veneer itself. That would help explain why it happens in some cases and not in others; it may be related to the species. The cases I've seen show discoloration on some panels, but not others, and not over the whole face of the panels that are affected. This leads me to believe that the thickness of the veneer may be a factor, although it could have something to do with uneven glue application or variations in the concentration of the fire retardant chemicals in the panel, or the distribution of aromatics in the veneer. If anyone has seen this problem in NAUF panels that are not fire retardant I would like to know about it. We have been working on the basis that only fire retardant products are susceptible.
I believe that a cross band between the face veneer and the fire retardant NAUF core would probably prevent this problem. Logically a non porous cross band such as phenolic or HPL backing sheet would prevent the chemical reaction.
I have been disappointed by the reaction of the industry. None of the parties involved seems to want to do the research to find out what the problem is or how to avoid it. Everyone assures me that it must be someone else. Woodwork Institute has made an effort to at least publicize this problem, and is recommending cross bands as a probable solution.
Note that I am no longer with Woodwork Institute, and can't speak for them.
Steve Taylor |
ken hercenberg
Senior Member
Username: khercenberg
Post Number: 626
Registered: 12-2006
| | Posted on Wednesday, October 16, 2013 - 04:49 pm: | |
Steve, thanks for your insights as always. Do you see any downside to using a cross band other than cost? Any special concerns that we would need to address in our specs?
Best of luck to you in your current endeavors. |
Steve Taylor
Senior Member
Username: steveatwi
Post Number: 64
Registered: 07-2008
| | Posted on Tuesday, October 22, 2013 - 08:05 pm: | |
Ken,
The cross band slightly increases the chance that panels will warp. In most applications this shouldn't be a problem.
There is also the possibility that it won't solve the problem. I believe that it will, but none of the parties involved is willing to invest the resources to find out the cause.
As for my current activities: I continue to review specifications and write articles, mostly for Woodwork Institute. The change in our relationship was at my insistence. I've been retired for a couple years now, and find it harder and harder to find time even for token work.
Steve Taylor |
ken hercenberg
Senior Member
Username: khercenberg
Post Number: 628
Registered: 12-2006
| | Posted on Wednesday, October 23, 2013 - 04:22 pm: | |
When using cross bands, do we need to address balanced construction so that a material is put across the back of the panel to offset the 'pull' of the cross bands?
Steve, it's not that we don't want you to have some personal time. Your input is invaluable and we appreciate hearing from you. |
John Bunzick, CCS, CCCA, LEED AP
Senior Member
Username: bunzick
Post Number: 1540
Registered: 03-2002
| | Posted on Thursday, October 24, 2013 - 01:19 pm: | |
Ken, While I don't have the experience in millwork that Steve does, I would always use balanced construction. |
Steve Taylor
Senior Member
Username: steveatwi
Post Number: 65
Registered: 07-2008
| | Posted on Friday, October 25, 2013 - 07:19 pm: | |
John's comment x 2.
If you require compliance with the AWS, balanced construction is part of the standard. It certainly doesn't hurt to mention in the spec too. Sometimes they do read the spec.
Steve Taylor |
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