Darryl Keil Last Activity 2025-05-12 11:03 AM
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Dan Cook

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Joined: 2005-04-11

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Subject : wrinkles in maple veneer
Posted : 2011-01-14 7:37 AM
Post #36243
I just laid up a table top yesterday and all looked good. This morning when taking it out it had wrinkles about 6" long x 4" wide in 3 of the corners. They are bad enough that I don't think sanding will get them out without going through the veneer (maple). Can I put another layer over the top of this veneer. The other side is backed with like veneer so the panel is balanced now, but another layer??? I am trying to save what is left. I used the urea formaldehyde glue (powder type).


 
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craig tufankjian

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Location: syracuse ny 13208

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Subject : RE: wrinkles in maple veneer
Posted : 2011-01-14 8:06 AM
Post #36244 - In reply to #36243
Ahhh maple.... "the other white wood". maple is one of those wait and see woods,you do your lay up ,put it in the press, and "wait and see if your screwed".

If the urea you used was mixed with water and not a chemical binder, you got a shot at re-activating it with a damp rag and an hot iron set on wool setting. Place a damp but not soaking wet rag over the wrinkle place the iron on the rag and press flat. The steam from the iron is hot enough to re-activate the glue.

That is of course if the wrinkle is not more that 1/8th in height.


 
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Dan Cook

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Subject : RE: wrinkles in maple veneer
Posted : 2011-01-14 11:39 AM
Post #36246 - In reply to #36244
I did use the powder type urea but no luck with the iron and pressing it down. It only appeared on the outside 4 corners of the tabletop and all the rest of the field is fine. I was able to sand out 2 of the corners, but the veneer was starting to show through on the 3rd corner so I stopped. The 4th corner I tried to loosen with a putty knife and see if I could get some glue underneath and then clamped it with a block directly over it, but I don't think that is going to work either. What if I sand it out and recover with another layer (I am using raw wood veneer). What would be the reason that this happens so I can avoid it in the future?


 
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craig tufankjian

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Location: syracuse ny 13208

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Subject : RE: wrinkles in maple veneer
Posted : 2011-01-14 12:00 PM
Post #36247 - In reply to #36246
sometimes it can occur from unequal distribution of pressure when pressing or the unequal distribution of glue and it welled up in certain areas of the panel.

Maple however is problematic regardless of the cut, birdseye,curly, quilted ect...


 
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Dan Cook

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Subject : RE: wrinkles in maple veneer
Posted : 2011-01-14 3:56 PM
Post #36248 - In reply to #36247
What are you guys doing to avoid this problem. I have used pva glues in the past but quit using them due to slight lifting of seams a year or so after projects were done. I know that people lay up maple panels everyday. There must be something that can be done to stop this from happening.


 
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Don Stephan

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Subject : RE: wrinkles in maple veneer
Posted : 2011-01-15 7:24 PM
Post #36251 - In reply to #36243
Dan:
Let's rule out the obvious. Glue wasn't expired. Even layer of glue thick enough to leave ridges when finger dragged through it. Thirty min or so from mixing to put in bag. Room temp above 70 deg F several hours before and throughout pressing. 25 or so psi. 1/4" or more top caul. The wrinkles are excess veneer, and not dents in the surface I get sometimes if plastic cover film had a fold. Substrate baltic birch ply or MDF.
Was the maple flat or quarter sliced, burl, quilt, . . .? The sheet very flat before pressing.


 
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Dan Cook

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Subject : RE: wrinkles in maple veneer
Posted : 2011-01-16 12:09 PM
Post #36255 - In reply to #36251
In answer to questions. The veneer was maple flat cut. I press in a flip top press. I called Daryl who has always been a great help, and he suggested running the panel closer to the edge of the press inlet instead of out more in the middle. I ran the top through our widebelt and took the veneer down to almost bare again (I used a 1 1/8" part. board substrate) and ran new veneer over the same face again. This time no problem. I had a couple of the seams open slightly, but other than that perfect. I used powdered u/f glue, and checked that it was in date. Mixed according their chart and spread good even coat. Maple was pretty flat. I use heat lamps above the press and measured temp at top of press at 98 degrees. Left it in the press for 8 hours before opening. In the last post, what do you mean by excess veneer?


 
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ckurak

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Subject : RE: wrinkles in maple veneer
Posted : 2011-01-17 9:23 AM
Post #36256 - In reply to #36255
Dan,

How did you measure the temperature at the top of the press to be 98? I use an infrared thermometer gun to take measurements. Simply point and shoot, then read the results.

What was the temperature below the press?

Is it possible that the first time you ran this that the shop was cold and the bottom of the press was cold as well? If so, then maybe the workpiece never got above the prescribed 70 degrees?

FYI: In cold months I use a heating blanket to warm up the table before pressing, then use the heating blanket, with an insulating comforter over that, to keep everything warm during the pressing process. I have a flip-top press as well. It takes a bit of time to get the thick table warm.

I have heard of guys placing heaters underneath the table as well. Be very, very careful of fire hazards if you do that though!



 
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Don Stephan

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Subject : RE: wrinkles in maple veneer
Posted : 2011-01-17 7:36 PM
Post #36257 - In reply to #36255
That question was trying to confirm what resulted in the three problem corners. I've had surface damage (dents) when a plastic cover sheet got wrinkles in it as the sandwich was being loaded into the bag. I use probably 6 mil plastic, and when it folds back on itself under the caul the extra thickness will compress the surface of the veneer. In your case I'm guessing the entire area of veneer was higher than the surrounding areas, as if there was a thicker puddle of glue underneath, but that the veneer was glued tight. Not sure how this would be possible if there was a 1/4" top caul over everything.
I have experienced areas of veneer lifting during removal of the veneer tape. Often I belt sand until most of the veneer tape is removed, then throughly wet the veneer and remaining tape with a wet sponge for several minutes until I can easily remove the remaining tape with a thin putty knife. I was behind on a project so I started vacuum pressing late in the afternoon and left it overnight. That was of course the one time the furnace quit, and the workshop temp was down to 50 the next morning. After wetting the veneer several bubbles formed where the glue had not bound the veneer to the substrate.
Which of the three best describes the three problem areas you experienced?


 
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Dan Cook

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Subject : RE: wrinkles in maple veneer
Posted : 2011-01-22 11:06 AM
Post #36262 - In reply to #36257
I think you all are on to something. I remember that it was very cold in the room the first time I pressed the veneer. Although I heated the room up quite a bit and the surface was at 98% it probably took an hour to get to that temp. The second time I pressed the tabletop I had no problem. Heated the room up an hour or so before pressing and used the heat lights as well. Temp. again was around 98% at the top of the press and the veneer(from the same flitch) laid down perfectly. Top came out very nice and completely tight all over. Daryl did suggest that I move the piece over in the press closer to the exhaust edge and I did this as he said I would get better pressure there. Anyway this all seemed to work in my favor and the results were a good press. Thanks to all who gave me good advice.
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