veneer wrinkles


    I had something happen that has never happened before when putting down veneer. After the veneer was down and smooth I put polyurethane on it. As the poly dried, the veneer wrinkled like cloth. What was my mistake?
    
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What Kind OF veneer and what kind of adhesive ???????

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:     I had something happen that has never happened before when : putting down veneer. After the veneer was down and smooth I put : polyurethane on it. As the poly dried, the veneer wrinkled like : cloth. What was my mistake?
You didn't use contact cement, did you? If you did, it could be the finish dissolved the cement (one of a couple reasons contact cement isn't the best thing to use for veneer).
    -- Andy Barss
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Andy is right about poly and contact cement. If you are using contact cement, after getting the veneer good and flat let it cure out a few days before putting on the poly.
Roger
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I agree with the posts. What happened was that the poly reacted with the contact cement causing the bond to fail. I assume that the veneer was not paper backed and had no seal coat before you applied the poly. Contact cement is one choice for laying down veneer but very unforgiving. One should always allow whatever glue to cure properly to minimize veneer failure.
The majority of these failures that I see come into my shop are from contact cement and a water based finish applied. What I have been able to determine that the failures result from not allowing double the cure time and when a water based finish is applied as the water opens the veneer and allows the chemical reaction to take place. Thus the failure.
When we must use non-paper backed veneer we always add a backing to it. We do this simply by taking some very thin paper such as tissue paper a brush some thinned glue on it (1:4 ratio) works best. When the veneer is placed, we then wash the veneer with clear shellac (after stained) 1:1 ratio.
Veneer bonded with contact cement can come apart if stained with a water based product. Remember that the contact cements capability to resist any solvent based chemical i.e. stain or finish depends on the length of exposure and its strength.
In our shop we use hide glue, yellow glue (aliphatic resin glue) and PVA glue. Our shop rule is simple if its veneer we will not use any mineral spirits based product. If you need to remove the piece then use Lacquer thinner, if you need to reset a veneer section then soften the contact cement with Mineral Spirits. But remember contact cement is mostly a rubberized glue and will deteriate and dry over time.
You can also take a heat gun to remove the veneer from the contact cement as well. The heat gun will dry the glue and cause it to crystallize.
Fixing the wrinkles. Ok, since we see this so often at our shop we will first take a iron and set it to medium-high, then we take a terry towel and lay on top of the wrinkle. Now here is the trick! apply the iron to the area and count in seconds start at three seconds and remove iron and terry towel. Are the wrinkles flat? If not repeat and try again. Now be very carefull as to much heat will either burn the veneer or cause the contact cement to crystalize at which point you are screwed and you will have to replace the veneer.

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On Thu, 09 Oct 2003 21:49:00 +0000, Not Telling wrote:

Have you tried "Titebond Cold Press for Veneer", and if so, what is your opinion of it? Here's a brief description:
http://www.rockler.com/findit.cfm?page "20&sid998
-Doug
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Doug,
This is an excellent glue for large surface areas and not really made to handle smaller assemblies. It also is formulated for cold press operations that can deliver at least 100 to 250 psi constant pressure until cured. We have cold vacum presses here but are unable to vacum a majority of the work because of size, and geometry. I am not condoning the use of this glue but in our opinion it is better suited for cold presses for which a lot of wood workers do not have the money for. We use this glue but not very often, but when we do its reliability is 100%.
Because the nature of our work and how often we work with veneer the preceding email is what we found has worked for us in a consistent manner. One thing we have learned and still continue today is what works for one person may not work for you. Only experience will tell. The best way is to experiment and learn from that experience. We have many people ask us what is the best way or what is the best application for what I want to do. This is one of the most difficult questions to answer since it has so many variables such as material, skill, application, tooling, location, temperature, humidity, just to name a few. The best advice I can give take the time to experiment and always follow manufactures instructions. This will be your shortest path to delivering a quality product that you yourself will be proud of.

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Hello Not. I've got an antique clock that I'd like to perhaps consult with you about. Would you mind telling me where you're located? If you'd like to do it off group, my email addy is valid.
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