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Forum topic by Arthouse posted 07-11-2011 02:54 AM 2772 views 2 times favorited 8 replies Add to Favorites Watch
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Arthouse

250 posts in 2110 days


07-11-2011 02:54 AM

I used walnut veneer without the paper back on a curved surface bender board plywood. I glued it with water based contact cement a normally very adhesive and strong glue . I ve noticed the veneer is lifting in a variety of area’s not because of bubbles or not enough pressure but in area’s lenthwise with the grain . I want to know from you smart woodworkers if it is the surface of the bender board or the veneer and what do I do with it now.

-- "The hand is the cutting edge of the mind but the wind and sun are the healing factors of the heart


8 replies so far

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fussy

980 posts in 2510 days


#1 posted 07-11-2011 04:07 AM

What kind of wood is the veneer and how tight a radius are you using. How thick is the wigglewood, and did you bend it before you veneered it or after. Had you finished it before you noticed the lifting and if so what did you use? At any rate, in my limited experience (none with water-based contact), I might try injecting more glue into one lift at a time using a small gauge needle like we diabetics use, press it till dry and if that works go to the next one. I don’t think water-based is reversible; maybe with hot water. What do the instuctions on the can say. Wish I could help more. Maybe some of these guys can come up with something better. Theere’s a lot of talent out there. Good Luck.

Steve

-- Steve in KY. 44 years so far with my lovely bride. Think I'll keep her.

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Dan Lyke

1510 posts in 3584 days


#2 posted 07-11-2011 06:28 PM

I tried contact cement for veneer, and gave up on it because any humidity at all caused wood movement and bubbling.

I’d try using an iron to see if I could get it to re-adhere, and then quick putting a finish over it.

For an adhesive in the future, I’m happy with using Titebond II, applying it to both sides (either using a disposable brush, or scraping it on using an old hacksaw blade), allowing it to dry for an hour (but not more than 12), and then ironing the veneer on.

-- Dan Lyke, Petaluma California, http://www.flutterby.net/User:DanLyke

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DrDirt

4166 posts in 3201 days


#3 posted 07-11-2011 06:42 PM

Like Dan – the water in the glue can swell both the top ply of the wigglewood and the veneer – and then once fully dry, they will have shrunk a different amount. Sounds like the wigglewood shrunk more than the veneer and so now the veneer is popping up to relieve the stress.
So the ‘why’ is sort of easy – but do fix or prevent is harder, because most glues are waterbased including titebonds, and the Unibond 800 or DAP. So did you bag this with the wood on a form? inside or outside radius?
Usually use wigglewood on a form, then the veneer on it (both sides) makes the panel into a rigid curved form.

There are a bunch of folks who do this stuff all the time on here – so i’m sure someone on here will have the answer.

-- 'Political correctness is fascism pretending to be manners' ~George Carlin

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EPJartisan

1116 posts in 2584 days


#4 posted 07-12-2011 04:29 PM

I am no expert, but here is what I learned from paperless zebra wood, walnut, faux ebony, and bloodwood. Glue and Glue vs Substrate makes the most difference, but you have to consider humidity since all are about moisture content vs cell structure.

Glue I have used ~ Contact, Veneer, Tightbond, and Epoxy. Contact has little penetration and allows both sides to move but good mostly for oily veneer or paper back, I have not used it successfully much. Veneer glue is viscous and works great for paperbacked but it seeps into open grained wood and does not stain… which is annoying and has an odd color. Tightbond adds moisture so if your substrate moves more or less you get gaps, cracks, or push up and the color is funny to deal with.. same goes for Yellow glues. Epoxy (West System) has been my choice for a while now, when I do not intend to stain.. penetrates both sides, sometimes too much but the finish is the same as varnish, and alas no stain can happen. AND epoxy is really unforgiving and really hard to repair. YET no matter what glue.. the longer the veneer sits open to the air, the little surface movements can make tiny push ups/bubbles and cracks along the grain or in glue weak areas. Substrate grain orientation and thickness (regarding movement) seems to make a huge difference as well. In a few months I am taking on another veneering project… with curly maple.. UGH I wonder how my temper will be with that kind of grain.

So I have fixed it like this.. Large bubbles and push up I make a small cut along the grain, and use an injection needed to fill it with glue (in my case epoxy or superglue) use a roller to push around the glue inside, before it sets. Cover with blue tape and clamp with wood or foam cushion over night. Find smaller areas and work them… not a fun nor fast fix, but it works… I am moving on to double backed Veneers. I know a place that will do it for your veneer.. in Indiana, but they have a great selection of veneers anyway. Double backed is veneer backed by a wood of similar movement laminated on the cross grain. You can bend it, cut it without cracking.. ,aminate on a radius…etc.. without bubbles or cracks!!! I have not used it yet, but a professional furniture maker friend of mine does use it for everything and has shown and convinced me to switch. FYI.. I have always hated paperback. Hope any of this helps.. I look forward to reading other peoples thoughts and fixes.

-- " 'Truth' is like a beautiful flower, unique to each plant and to the season it blossoms ... 'Fact' is the root and leaf, allowing the plant grow and bloom again."

View Dan Lyke's profile

Dan Lyke

1510 posts in 3584 days


#5 posted 07-12-2011 04:52 PM

On the moisture from the Titebond: Yes, it does mean the grain opens up when it dries. I’ve fought this by using cyanoacrylate (superglue) in the gaps while I hand sand with 220 grit. I am interested in playing with epoxy…

-- Dan Lyke, Petaluma California, http://www.flutterby.net/User:DanLyke

View BobTheFish's profile

BobTheFish

361 posts in 2011 days


#6 posted 07-12-2011 05:22 PM

EP: Curly maple’s never been a difficult veneer for me to work with. Figured walnuts, on the other hand, have been hellish. Birdseye you tend to have to watch for eyes popping out and it’s a pain to cut, but in general, the easiest woods have the smallest grain,and a nice even shrinkage. I also never use paper backed veneers.

When it comes to staining, I typically stain my veneer sheets, using a rag and some mixed stain, applying to both sides of the veneer for even penetration (I think typically it’s back first, then front, but it’s not a big deal usually. I just go with the best stained side, if there is one, as my front). You might want to consider that if you are thinking of still using your epoxy with stained veneer.

Typically I use contact cement, despite how many people are against it because I feel epoxy’s a bit too much to do in my living room, despite tossing down some cardboard and other protective measures (I’m messy and damn the carpets!), and I haven’t the space for a vacuum press. Yellow and other “regular” glues tend to have way too long a time frame for me to apply even pressure to, and get decent results… plus sometimes there’s glue marks at seams.

Arthouse, what you are describing seems to me like the veneer itself might not have been perfectly flat, creating those little bubbles (why I hate some burly uneven veneers), or your contact cement was not applied thoroughly, OR, the contact cement started drying, OR, you didn’t apply your veneer tautly to the surface (which is difficult when working with a curve), OR you didn’t apply enough pressure (using a roller would definitely help, if not at least using a heavy block (for weight and even pressure) wrapped in tape (to protect the veneer) ).

Moisture can sometimes be a problem, but I almost never see bubbles and buckles RIGHT AFTER applying the veneer as the result of moisture. It’s almost always an issue with pressure, keeping the veneer taut enough (you don’t have to stretch it, but you need to make sure it doesn’t contact the other glue surface further down from where you are working), or the glue/veneer itself.

Oh yeah. ONE other issue it might be: not letting the contact cement cure.

I’ve made this rookie mistake. You apply the contact cement, then cement the two pieces together, and you think because your contact cement is dry when you adhere the two sides, and you waited an hour or so it’s fine to apply a coat of poly. WRONG! The contact cement needs at least 24 (and preferrably 48) hours to completely cure, and the poly starts to interfere with your cement! all the sudden you have bits lifting, some odd bubbles, and the more you try to fix things the worse it gets.

Definitely not good.

But anyhow, yeah.. Walnut veneers are always bastards for me to work with. They just seem too damned wildly grained, and for some reason, my walnuts are far more brittle than any of my others. And I’ve done, oaks, maples, mahoganies, sapelle (my favorite), angire, etimoe, zebrawood, koa, purpleheart, and probably 20 others I can’t even remember…

But walnut is always the worst of the bunch.

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Arthouse

250 posts in 2110 days


#7 posted 07-12-2011 05:46 PM

Thank all for the interest. Veneer is a tricky business. I have read all the remedies for gluing veneer. The glue I used is a water based glue contact cement from wilsonart. I did not press with a bag I rolled it from one curve to the next with a roller and hammered it with a square block. I then sanded and laquered the piece. The glue was dry for sure for I used a heat gun lightly before appliying it. The lifting comes from the convex side not the inside curve . I think the problem is the veneer for the walnut veneer is quilted and it is sort of streatched on the curve and I applied it in two section to get a pattern . The wood was problematic to work with it didn’t want to cut it wanted to crack along the grain. I will try to sand down and apply a gap filler in the overlays that are not bubbles but more like a crinkle along the grain . Wish me luck Dan

-- "The hand is the cutting edge of the mind but the wind and sun are the healing factors of the heart

View BobTheFish's profile

BobTheFish

361 posts in 2011 days


#8 posted 07-12-2011 08:06 PM

That’s EXACTLY what happened with my quilted/burly walnut two days ago. The quilting caused unevenness in the veneer (enough I think to create bubbles) and it’s brittle as hell. The more I tried to fix it, the more issues I had. I’m sanding it all off tonight and starting fresh with a different veneer.

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