Best Gluing Practice with Shop Sawn Veneer?

[John TenEyck]

I make 1/16" shop sawn veneer, assemble panels in the usual with with veneer tape, and then glue it onto plywood, MDF, or particle board cores in a vacuum bag. By the time the panels are finish sanded I would estimate that the veneer is 0.050 - 0.060" thick. I've used Weldwood Plastic Resin Glue almost exclusively for at least years, but I also have used epoxy when I glued some to one side of Melamine after sanding off the coating. The MC of both the veneer and cores has always been between about 6% and 9% (30 - 55% RH), Winter to Summer in my heated, dehumidified basement shop. The temp. has always been at least 70F and I leave the panels in the press for 13 - 14 hours at roughly 20" Hg.

About 3 years ago I built a vanity for my own house, using ash over the sanded Melamine with epoxy, and on MDF with PRG. After a year I noticed one of the veneer seams on the Melamine panel had split opened a little. That was in the middle of Winter. The next Summer I couldn't see it. The next Winter I could see it again, plus a couple more. This Winter I see a split seam on the two doors of the cabinet, which were done with PRG on MDF. All of these panels are about 32" tall with the veneer running horizontally, so 32" of cross grain if you will. My house gets down to the same 30% RH in the Winter as my shop, and goes as high as 75% sometimes in the Summer unless the AC is on.

None of the seams on that cabinet were preglued when I taped up the veneer panels. I built a storage cabinet for the same bathroom 2 years ago, using more ash veneer over MDF with PRG. On those panels I did preglue the seams with TB II or III when I made the veneer panels. No seams have split open on those doors.

Last year I started rehabbing my kitchen using, you guessed it, more ash veneer, this time glued with PRG on composite panels - plywood core with particle board on both sides. I preglued all of the seams with TB II on the veneer panels before gluing them to the cores. Earlier this week I noticed a few of those seams starting to split.

So I've seen seam splits on particle board and MDF cores glued with both epoxy and PRG. I don't recall ever seeing a split seam with plywood cores, thankfully, because I have quite a few customer projects out there. I'm sure I would have heard; who knows, maybe the phone will ring any day. Most of the projects I've sold have used maple, white oak, and walnut veneer; none with ash.

I'm working on another section of my kitchen rehab this Winter using the same materials and process, except for a few panels that I substituted poplar plywood for the substrate just for comparison. I have always used the recommended spread rate for PRG of 1 lb of resin per 40 sq. ft of substrate, regardless of which type, but after seeing the seam splits I've increased it to 1 lb/35 sq. ft and it's noticeably heavier when I roll it onto the substrate. Of course I won't know if this helps or not for about a year.

This has been a real blow to my confidence in using shop sawn veneer, with real concerns for the projects I've sold. I'm looking to see what others are doing, what your track record has been, what you think I might be doing wrong, etc.

Thanks in advance.

John

[Mel Fulks]

Do you put glue on both surfaces ? I was taught to do that and I think it works better than one heavier coat. I also think it does better if you let the glue rest at least 10 minutes after mixing before using it . It used to say that in the directions,
I think they took it off just in case buyers might find that an unnecessary complication and just buy something else. We
always mixed it to where it dripped ,not streamed ,off stir stick before its 10 minute rest. John, I'm sure you've seen all
this before. But I would not dare to change the method I was taught.

[John TenEyck]

Thanks Mel. No, I only put glue on the substrate, not the veneer. The directions I downloaded 10 years ago or so caution you not to put glue on the veneer because it will curl, and just putting the panel with glue on it will cause it to do so if you don't work quickly. I have always used the glue immediately after mixing, but I recently wondered if letting it sit for 5 or 10 minutes might be beneficial. Below is from Weldwood's current website:


PREPARATION 1. Surfaces should be clean, dry, smooth, and free from all foreign material. 2. Water temperature must be between 68°F (20°C) and 100°F (38°C). Higher water temperature will result in shorter working time. 3. Measure powder and water into separate containers. 4. Add powder slowly to the water while mixing continuously until uniform mix is achieved. Final consistency should be a smooth, creamy paste. 5. If mixture does not combine to smooth consistency, or mixture results in a gritty or lumpy texture, product may no longer be suitable for use.

APPLICATION: 1. Apply a thin coat of glue mixture. Application of glue on only one of the bonding surfaces is generally sufficient. Use a paint brush, paint roller, 1/32” notched trowel, spray gun or conventional glue spreader. 2. Clamp or screw bonded materials together with sufficient pressure forcing excess glue from joins to release trapped air bubbles and ensure maximum adhesive coverage between surfaces. Refer to table below for recommended clamp times. 3. Clamping Pressure Required: 50 PSI for softwood or well machined hardwood; 175 PSI for rough cut softwood materials; 300 PSI for rough cut hardwoods. Finished glue line thickness should be from 0.003 + 0.006 inch for best results.

Still nothing about mix time/rest time. But now they say glue on one side "is generally sufficient" which means sometimes it's not. It's still not practical to apply it to the veneer, IMO, so using more glue might be the correct solution. I've wondered about glue spread rate before since a vacuum bag applies less than 10% of recommended pressures.

I have done some peel testing on samples. Typically the bond is so good that the veneer chips off taking pieces of the substrate with it. But once I was struggling to get the parts under vacuum before exceeding the open time. After curing I could see the bond was poor along the edges so I tried pulling it off. Some came off in full length strips with just sporadic coverage of glue, while some was well bonded and pulled up the substrate.

John

[Jamie Buxton]

The plastic resin glue has water in it. Perhaps that water is making the veneer wider while you’re gluing it down. When the water eventually evaporates, the veneer is trying to shrink back to its original width. To test my guess, measure the width of the sheet of veneer before and after the gluing operation.

Me, I glue sawn veneer with epoxy, because I’m leery of water in the glue. I use West Systems. I use plywood for the substrate. So far I haven’t seen seam failures. But I have admit that the humidity swings here are narrower than in upstate New York.

[Mel Fulks]

With the 10 minute rest the stuff does act diferently ,it no longer beads up requiring more brushing for even and complete coverage. It's possible that the small gap that opened was caused by a little moisture making "compression ring
set" in normal use.I think glue between the pieces is needed,certainly I concede that getting glue there is almost unavoidable
I mention it only because if you wanted to avoid it I'm sure you could do so. I'm sure you will figure out a small new
procedure that works and I look forward to reading it.

[Jamie Buxton]

I should mention that I don't edgeglue the veneer leafs together. My reasoning is that if I do, I might get lippage. Then, when I glue the veneer to the substrate, I'd have an air gap at one side of the seam. So I just veneer-tape the leafs together, and glue them down.

[johnny means]

Hate to ask, but are you putting your veneer tape on the exterior side of your veneer? I've seen tape under the veneer be a point of failure. The tape splits when subjected to sheering force.

[Jeff Duncan]

I do a lot of stuff with shop sawn veneers and have always used plain old yellow glue. If the pieces are thick enough, like your 1/16" pieces, I edge glue them as well. I don't generally use veneer tape, I'll just use blue tape on the outer faces to keep them tight while I get them into the bag.

Outside of your gluing practice you may also want to consider the humidity aspect of your situation. If your home humidity is down to 30% I'm guessing your not providing any humidification to your home in the winter? This is going to cause everything wood to completely dry out and shrink. I myself keep 3 humidifiers going pumping about 4+ gallons of water back into the air daily this time of year for an apartment under 1000 sf. Even then it can be tough to keep the relative humidity at a decent range, but its WAY better than not humidifying at all.

just something to think about,
JeffD

[John TenEyck]

Thanks everyone for the added input.

Mel, you may be on to something. I notice that the glue tends to sort of fish eye when I first roll it out, using a foam roller BTW, but after a minute or two I roll it again and it lays flatter, like finish does when it flows out. I'm going to try letting it sit in the pot for 5 or 10 minutes next time before spreading it. And I've got a couple of seams that look funny but aren't split, at least not yet. They look funny in that the dye toner doesn't looks a little lighter on an 1/8" on each side of the seam. No one else but me sees it, but it almost looks like when you get yellow glue on wood and don't get it all off. Maybe this is compression ring set you mentioned. Or maybe it's just the quarter sawn character at the edge of those pieces being less absorbent or reflecting light differently. Other panels made in the same sequence in the same way look perfectly normal.

I'll post some picture tomorrow, but tonight I split apart a couple of panels I had put maple veneer on by mistake instead of ash. The veneer tore the particle board substrate apart, including right up to the veneer seams.
Where the hardwood edging was, however, it split cleanly along the glue line. That was not encouraging, but I've never had a problem with any panels over time. And I saw no glue between the seams, which there actually should not be if the seams stay tight. So if you need glue between the seams you need to preglue them or use a glue that better absorbs into the seams.

Jamie, I stopped edge gluing for the same reason you mentioned, edge misalignment. I think the cracks I'm seeing on one panel might be due to that problem with some veneer that badly misbehaved.

Johnny, I've made a lot of mistakes over the years, but I've never put the tape on the wrong side of the veneer yet. I have even stopped putting blue tape on the inside before veneer taping the outside thinking it might leave some residue on the wood that could interfere with the PRG.

Jeff, one would think that if the panels were glued up in the Winter, which some of them have been, when my shop humidity is at 30 - 35% that I would never see seam splits, only puckered seams maybe in the Summer at high RH. I tried a humidifier years and had dust everywhere so that didn't last long. I'd have to go a different route if want to consider that again. Are you using a vacuum bag with yellow glue? If so, how long are you leaving it in the bag, and how long do you let it "cure" before further processing? With PRG, the water added to mix the glue is consumed in the formation of the UF glue so when it comes out of the bag it's dry and rigid, though not fully cured for 7 days. I tried Better Bond once and had immediate seam lift. I probably used too much glue but I never tried it again, especially after I talked with Joe Woodworker and he told me it's not recommended with shop sawn veneer. Now his website says that, too, though it did not when I used it. But I've never tried plain TB or TB II on large panels, just a few small things like a drawer front that I mechanically clamped. I've always thought you need a rigid bond to keep the veneer bonded to the substrate as one unit so they move as one; maybe it's time to rethink that assumption.

Jamie, again, one reference I cited in my first post was a panel glued with epoxy. Also, my friend had a panel of Sapele shop sawn veneer glued with West Systems epoxy on particle board develop a huge split in it - during the first Winter. That panel was made in the Summer in an unconditioned shop, so the RH swing would have been even greater than mine. But I have thought about going to epoxy just to get more open time. Despite what the literature says for PRG, I find I only have about 10 minutes to get it into the bag after putting it on the substrate.

Anyone using polyurethane glue?

John

[Mel Fulks]

John, .....give it the whole TEN minutes ! It's not like 5 minute epoxy, the time does improve it. As I said it was part of
instructions for many years. One of these days I'm gonna call Weldwood and ask why they took it off the label .

[Joe Hendershott]

Wanted to ask you John, and others as well why you do not use cold press veneer glue? While I have done only a few jobs and use commercial veneer have had good results with the titebond brand.

[Kevin Jenness]

Joe, Titebond cold press is a PVA with crushed walnut shells added to prevent bleedthrough when pressing thin sliced commercial veneer. The additive is unnecessary with thick veneer, and the greater movement potential indicates a more rigid glue than PVA.

I generally use epoxy with thick veneer for a rigid glueline and long assembly time. One advantage is that epoxy will be sucked up into the joints between leaves in a vacuum press, bonding them together.

A point that is sometimes overlooked is that epoxy bonds best to rough surfaces, sawn or sanded at 80#, especially when gluing dense woods.

[David Zaret]

i do a lot of veneering with both shop sawn and commercial - what i've found is that i have to keep the shop sawn no thicker than 0.050" or it'll act like solid wood. for glue, the best success i've had is with unibond (2-part urea resin), thickened with the blocking agent. the thickener doesn't impact adhesion, but yields a better, heavier glue layer. with those variables, i've not had issues - the few times i got lazy and used a thicker veneer, i had (minor) seasonal cracks.

good luck!

-- dz

[Robert LaPlaca]

John, I generally don’t use too much veneer for the furniture I build, but I have had really good success using Unibond 800 for the veneer glue.

One project I had, needed crotch Walnut veneer shop sawn veneer (1/16”) applied to drawer fronts and two fairly good sized raised panels, the veneer was applied over quarter sawn Walnut core. Everything looks as good as the day it came out of the bag.

[John TenEyck]

Thanks everyone for the added input.

I have used Unifbond 800. It worked fine but the only piece I have with it is with paper backed veneer so I have no direct comparison to PRG with shop sawn veneer. I moved to Weldwood PRG because I could buy it locally, although now I order it online. Both are UF glues, just in different forms to start with. I don't know if there is any real difference in how well they bond or their physical characteristics other than both form rigid bonds. FWIW, I have used PRG on exterior doors to glue 1/4" thick veneer onto both LVL and stave core cores. No problems yet, though those are narrow and mostly without seams, and hoping there won't be. And before anyone says that's crazy and I should have used epoxy go look up the strength loss vs. temperature for epoxy before you do.

The point about epoxy wicking up into the seams could be a really important one. The panel my friend had the split seam with, using epoxy, might be illustrative in that he preglued the seams with TB. One of the reasons I've never been sold on pregluing the seams is because you can't clamp the joint, you can't even create a rub joint, it's just held together by the seam tape. So the bond is inherently weak, and that's where it let loose in his epoxy bonded panel.

It's clear to me anyway that part of the problem I'm having is the veneer is shrinking more (at least at the seam) than the substrate, or at a different rate which makes sense when you think about how moisture moves through the thickness of a panel. I looked at the cabinets in my house that I've made with commercial veneered plywood; not one seam split. Of course that veneer is only 1/40" thick or so and it's cut with a knife so it's "creped" and inherently weak across the grain, which could be an advantage in moving with the substrate. The glue in commercial veneered panels is at least as rigid as what I'm using. I have no idea how they join the seams however.

I did some more tear downs last evening on panels I glued up a couple of weeks ago. I'll post pictures later today.

Going forward, I'm going to order a humidifier today to try to raise the humidity in my house to something over 40%. 45% would be a good target I think. I'll do the same in my shop with a humidifier that I already have though it may not be big enough for the space. I will let the PRG sit for 10 minutes, then restir, before using it. I'm going to look into moving to West epoxy; it has advantages and disadvantages, like everything. And if I have to replace all my kitchen door/drawer fronts (I hope not but it's not looking good) I will use a different substrate, most likely MDF but maybe BB plywood.

Thanks again. More to follow.

John

[Brian Holcombe]

John, I also don't glue the seams. I don't see the point as I can always see glue having been pulled through the seam after taking the panel out of the press.

[John TenEyck]

Brain, what glue are you using?

[Brian Holcombe]

John, using titebond II currently.

[John TenEyck]

Thanks Brian. That's interesting how it sucked up into the seam yet PRG doesn't.

John

[John TenEyck]

Here are some photos I took of maple veneer glued with PRG onto the composite core substrate. I think this was from 1 lb/40 sq. ft coverage but can't remember for sure.

Here's the panel after I peeled off the veneer near the seam, but before opening it.

https://lh3.googleusercontent.com/agR1Mg5NIPZjI5f6zGGAsKyC6ZbZ_N2fqev6RAhMB1FzPBlOo-6XvZXeZoTF1rFNtrpwYIvHDV5_96Ietk4_qujugZ8XoJdGzaRg JSp3HGhQ9qupv3mEon3zZXa4410jL1st2jcYEdmwKUb5urHXpP 6Cw0uRWUJAcGZI9u-DcVpi0qsEei5kYnKIRmK9-V3_JKJFrD0KdsgQjppNDUlrXhqHAXi8c-XjQLRcpJmogzh0-uvdKzWzfpAS4EfAB4EvT1kkBi5hriRMz1urW6aW_3EGGK--rVUc7DzjchBh6PiuT9UOgsjZHF031onSO2b1qKoYbGxgilJ-8v5ZDv-MDow4jzp7XKRAUqL5Cz6sVs6MT4hQf4axTswHWlS9iyAq6dL4E MvmogHhkrRtaTRXJJZZsdOrnvetQv2rvX1nx4TBmgtLXvqtGqm Je7R46Y5Cp8XkUYSYhDFAYmAmTuUD7ABq0SPL3Z-Jcae02fYd5KXK8UvBq1p1FY3j4DFWTJkDZ_oZZuA9N05U1sMP0 q2An3YlTLU8hOrWfW_qJYS6r_f42MzpGELGBU3dQbFZbJMOXTA 1vKuc_wNozUUqyJA35pLwaBenJgNvKAzl_Opv5nf0iLP5z7zHH NehZTdYfztRSSE1F6gbgYq3NQcE5uZGCyWemqHrmJfV=w835-h626-no

After opening the right side.

https://lh3.googleusercontent.com/Q2_eReYA6XoyR3I7zHaFxOUqui5aBG_x4n5bj-E0lVOgvSJ_kVBFuAtaLBTDA50cQ-RJk2VH31RQuC7jkW286QKjPntSN4U-RrYop8-h9MTVMw0p1cV-naxmbcMZ5nkvNT6N4LJJJdjkVMrXZeWsVSy2jCB9uCrym9bPrI dlxUABJw7tLw6fJ4v6kuVqv4M2pQ7ONY3rVOG21MdONizLK0zM mE-0wzGPsc_wIE5NRX1h3iBPM6dZj4-hJ802SY6F_lpl5icvGPH8RDLbT-fv40vN6tVbyaz0gVwXLnv0XI8IFIWLZCbgeJa7ufal7wJBTzX3 NDvgQucgugM0_4_A5TdkdkzUOaiXP8J4cAwMAFArpRb3ppUL80 eDq_PHaZTo0FGZ4irRH1n-htR3MyJnkhW4K6v9IL3UZeGxYQz36eTtpzrVMEN54UyS6zgjQN dHc3ek_f4czTUpAGyAJQrOKZfaEg8OcSxfaAkLAH6s8pybbjZW GiHjeNbnV5XBaACg79T6Z6Vsa_M7lK4CBmIBGtzsmm9fLc8iH2 tnnezGRa75LEKe1dYTIC8w6hvlxC0VBOkryyuqzRpKaGLMg45Y b6YLfZB2WHdZck9-oQp4kLH6RP0QX4vIstefd3dsK1Hs-1lA5La8QjnCuXykKo9qmo2nonJ5awzt=w835-h626-no

On about 90% of the area the glue pulled up the particle board; just a small area near the bottom where the glue let go from the veneer. On the area where the hardwood edging was the glue split cleanly not taking any of the veneer or edging with it.

Looking closely at the edge at the seam.

https://lh3.googleusercontent.com/2Sy5AAHUWO2OrEaYW6Hieqx3eFGFUeZsmBUBQTcq_zB6xT9Cwc TP7cXHqUv8GwzGnyidOs0-efQDRoof6osLpI7_hwF8yUGC8KxZkv0E2hT7Y6_JuwgjpsGm95 sUvbWp25YHX5-Rw-IPAvuvPyEz3JWRBPZtGRJWc8abV4HBFBteqQcst_tViunw_A4z EVdge47rhHzBl9i4K1N5FRqpU6_tP-LOOHiRPRGN5P6hc_c077JOoLjob2XdA51H9itOEyC7RCxxzzV_ mlYiSVaRkkegMFCVVHEe8vB6BpJRq_fOkOJ478uEZut8mMmrYM 7QyUVN2i5pFOcjbv1ik7PKSF3y3K-bgpbfU6VjT3bqPIuWdDoARhEpQlJxk_fHq0Z02yLLox5r-atvzoNE1gu9buGV8yKC0ROvrZPtQat7Rq8AkHCndcS5RLY9JQ5 jWH4XigYcQ15HF7PoKjaET_S9yHb6dqwGMTBt6_3XLbU_HdKVm ibVood37a0BqRMt6icPJRxzegsGrOVYkkF_GZsUnI4yMbTBFR6 d-bqUVOuzEXi8WV6IqAmDmScYI_axVWj4v5SJljDU8IbFSrZZ3Z5 Zf35Wm7r5RZ3wOFvjtmMYQ7J6dG4nu2pvj6V8O0Seor1_25JDR 9HRAWIuta00MS7i9iNPFijnReHt=w835-h626-no

No glue. The other side is the same. I guess I know how to make tight seams. But you can see that the veneer was bonded to the particle board at the seam. Looking at both sides is shown below.

https://lh3.googleusercontent.com/WKAKvG2vN6cF-gJhONb3HV0XLM3j3nuIO3E-mfHa5Ge4ea8vSRJygjZ2i3_t19jOFGRF5YO6RLiH1Fw9g8nDZU mmk0tG_WV-H07o1aC8qpVejLzYJze-j-pMwk34MeV4wvhiZp6OHJ7jZ62ulGOUK330p-zrK5FX1VJNKte9GyWMz-hkhPn-qshrCKgGpFdc85W75WxPO1DX1QJj_hvZEa94A2xto7wGjWX6Hr RfGVlMUi1DB2fmYxjBHSRAKIrrp5A9fQWqZcvdFSpkySQYeNVO VMgl-Xj7KNR81obu2-114c7iNw7uKa7ToWBlItlICXt-N8pBLSP1pl6XNX_H0TcZ0bi6AiMKbhoQ4CmOuhC614d4V2GJeD LXLAWhHCulrz_bHCI987EcBFrn8szYwu_Wtf_2-f1ZjT1ftcmpl4-79N61NoAAgl8wbz0-rSDDNR8kv0DQAzJD7lh_z-U0treUzPA2vvNhmzTnW6edCWGfjpQjjT6CwwhcIT7uhJKKKoHf En5blXWmUPFMRyAESNTBeouq6_zxM9-4fGQ7XGaxfgO-bpGzGv5QaPwKYJE37hwTG7sCHMPdKalqjhN9K4VC12Y8u3iiro FS7UzMpwIXrdQr2WMmxpG8xA2C6OSO5SjaDho-jgUiNyJGBut8d8XxhMUFSxzj=w835-h626-no

Most of the seam openings I've seen are where the veneer is curling away from the substrate. In that case, either the veneer was not bonded well to the substrate or the veneer was bonded but the substrate is delaminating. I can't look under any of them yet so it's hard to say which is the case.

I certainly do not like the poor bond at the hardwood edge. That might be reason enough to switch glues.

Comments welcome.

John

[Mel Fulks]

John, I saw your mention of the low pressure with vacuum bag. That makes me think you will have to
put glue on both sides, that is actually less messy and more dependable than one heavy coat. Or go to a different glue. I've posted two or three times about how well PRG works with glue on both surfaces ,material covered with plastic to
prevent adhesion to caul ,spring clamps around perimeter, weight in middle. That glue has a strong
atraction to itself. I've seen failures on bent laminations where one heavy coat was used on each layer
and none where glue was applied to both ( or all).

[John TenEyck]

Thanks Mel. I know you mean well but I take it you've never put waterbased glue on veneer. You can't believe how quickly it will curl and become unmanageable. If putting glue on the veneer is required I would switch to epoxy.

John

[Jeff Duncan]

I generally go by instinct on the time in the bag. I spoke with the Titebond guys some years ago when I had a tricky project to do to discuss how long parts should be kept in the bag, and they were pretty un-helpful in that regard. So for flat work I generally leave it in the bag under pressure for two hours, or sometimes more if I have the time. For curved work I go longer based on how much tension there is on the parts. As a really rough example.... if I can hold the parts to the form with little force, then 2 - 3 hours is fine. If it's something that requires some exertion to make the parts comply I'll shoot for 6+ hours to be safe. With TB 1 or 2 there will be a bit of spring-back on curved parts. Not a lot, but you do have to account for it.

As far as bleed through goes.... if your using shop sawn veneers roughly 1/16" thick, bleed through should not be an issue unless its some really tricky burl type stuff or??? With paper backed veneers same situation, no bleed though worries. I usually order my veneer paper backed for just this reason. It's only non-backed veneers that the bleed through can be an issue. I've done them on occasion with older veneers I've had in the rack for a while and have been pretty lucky, though I know some stuff can be problematic.

I use a variety of materials for the cores. On large flat pieces I really like mdf, or if it needs to be more structural then a veneer core with hardboard faces, ie Pluma ply. On small parts for furniture I'll do solid cores glued up from stable hardwoods.

good luck,
JeffD

[John TenEyck]

Thanks very much Jeff. One more follow up question or maybe two. What spread rate are you using? And how long do you let the panels sit after coming out of the bag before further processing? The water in TB glues can't evaporate while in the bag, only migrate into the substrate. Thanks.

John

[Joe Hendershott]

Joe, Titebond cold press is a PVA with crushed walnut shells added to prevent bleedthrough when pressing thin sliced commercial veneer. The additive is unnecessary with thick veneer, and the greater movement potential indicates a more rigid glue than PVA.

I generally use epoxy with thick veneer for a rigid glueline and long assembly time. One advantage is that epoxy will be sucked up into the joints between leaves in a vacuum press, bonding them together.

A point that is sometimes overlooked is that epoxy bonds best to rough surfaces, sawn or sanded at 80#, especially when gluing dense woods.

Thanks for this, learned something valuable.

[John TenEyck]

Jeff, you mean this stuff? https://www.dropbox.com/s/memn43f39vq5h57/0024778%20proof_Atlantic_Pluma%20Ply%20HDF_2015010 2.pdf?dl=0 I was looking at that only a week or so ago. Looks like a very good substrate for veneering plus the structural aspect. But it looks like it's only made in 3/4"; I need 5/8".

As an experiment I took some 3/4" poplar plywood and drum sanded off the outer plies on both sides to get to 5/8" then veneered it with my shop sawn veneer in the standard cross banded way. It will be interesting to see how that performs compared to the composite core the rest of it has been made with.

John

[Jeff Duncan]

Yup, thats the stuff. It comes in a whole lot of sizes though I can't say if 5/8" is one of them, that's an odd size. I've used 1/2", 3/4", 1", and I even used 1-1/2" for a custom desk I built last year. The stuff is also pretty flat, almost comparable to mdf in the thicker sizes. Almost all my paint grade work is done with Pluma now as the finish on that substrate is excellent.

I use a pink roller cover I think is made for contact cement to roll the glue on, that way I get a good even spread. One side only, if I did both it would certainly be too much glue. Once the parts come out of the bag I usually let them sit overnight. As far as the "evaporation" aspect I don't think its much of an issue. If you think about it glue doesn't easily evaporate through solid wood parts even when not in a vacuum bag, so..... probably not a huge difference there?

Anyway I hope this helps a little, I should say I'm no expert when it comes to veneer work. Though I get by and haven't had too much trouble so far;)
JeffD

[John TenEyck]

Thanks very much for the follow up Jeff. Love the clean lines and gorgeous wood of that office space.

John

[Andrew Joiner]

Yup, thats the stuff. It comes in a whole lot of sizes though I can't say if 5/8" is one of them, that's an odd size. I've used 1/2", 3/4", 1", and I even used 1-1/2" for a custom desk I built last year. The stuff is also pretty flat, almost comparable to mdf in the thicker sizes. Almost all my paint grade work is done with Pluma now as the finish on that substrate is excellent.

I use a pink roller cover I think is made for contact cement to roll the glue on, that way I get a good even spread. One side only, if I did both it would certainly be too much glue. Once the parts come out of the bag I usually let them sit overnight. As far as the "evaporation" aspect I don't think its much of an issue. If you think about it glue doesn't easily evaporate through solid wood parts even when not in a vacuum bag, so..... probably not a huge difference there?

Anyway I hope this helps a little, I should say I'm no expert when it comes to veneer work. Though I get by and haven't had too much trouble so far;)
JeffD
Wow Jeff, beautiful work! What's the wood species and finish?

[Metod Alif]

Jeff, you mean this stuff? https://www.dropbox.com/s/memn43f39vq5h57/0024778%20proof_Atlantic_Pluma%20Ply%20HDF_2015010 2.pdf?dl=0 I was looking at that only a week or so ago. Looks like a very good substrate for veneering plus the structural aspect. But it looks like it's only made in 3/4"; I need 5/8".

As an experiment I took some 3/4" poplar plywood and drum sanded off the outer plies on both sides to get to 5/8" then veneered it with my shop sawn veneer in the standard cross banded way. It will be interesting to see how that performs compared to the composite core the rest of it has been made with.

John
The site says 3/8" - 2".
Best, Metod

[Ben Abate]

Hi Fellows,

Let me start off and say I don't want to hi jack this thread. I have one question about veneering and I did not want to start a new thread and a complete conversion. Hopefully one of you can give me an answer and that will be that.

I do veneering on occasion and this thread has been quite good to read. My question is I've never used paper backed veneer only raw or my own cut veneer. What do you use to put down paper backed veneer? I have to recover some veneered hollow core doors with mahogany veneer. I have my thoughts but would like to hear what all is used or available.

I hope not to cause this thread to go in another direction that was not my intention.

Thank you all
Ben

[Mike Henderson]

Hi Fellows,

Let me start off and say I don't want to hi jack this thread. I have one question about veneering and I did not want to start a new thread and a complete conversion. Hopefully one of you can give me an answer and that will be that.

I do veneering on occasion and this thread has been quite good to read. My question is I've never used paper backed veneer only raw or my own cut veneer. What do you use to put down paper backed veneer? I have to recover some veneered hollow core doors with mahogany veneer. I have my thoughts but would like to hear what all is used or available.

I hope not to cause this thread to go in another direction that was not my intention.

Thank you all
Ben

I only use paper backed veneer in very limited applications. In those applications, I treat it like Formica and use contact cement.

I'll just add that paper backed veneer is THIN - I mean the wood is thin.

Mike

[Ben Abate]

Thanks Mike,

That was what I wanted to know.

Ben

[John Blazy]

over the sanded Melamine with epoxy,

John

A little tip for you, if you like to veneer over melamine, as in my case when I wanted melamine interior (inside of cabinet doors to match interior of entertainment center), but exotic veneer exterior of cabinet. Use PL Premium polyurethane construction adhesive - works like a dream for several reasons: First off, PL bonds to melamine / HPL surfaces as a literal weld - never in my 30 years of gluing with PL to melamine, have I ever had it come off without abrading it off. No need to sand the melamine at all.

Second, is that the PL is solventless, so no shrink, which is what causes most warping during cure. Third, even though its high viscosity (pumped out of caulk gun), it rolls out great with rubber brayer roller. Even coat, and need to err on side of too little, because it expands as it cures. The viscosity also helps so it does not seep through pores. I veneered Pommele Sapele (open pore) and no bleed through. Then I sealed with epoxy, sanded, then topcoated with Auto urethane, then buffed. Still looks awesome to this day.

[John TenEyck]

Thanks very much for the tip, John. The Melamine literally trashed the sanding roll on my drum sander so your alternative is attractive on multiple fronts. I used epoxy because it has no water in it, but PL Premium sounds like a good alternative.

John

[Jeff Duncan]

Wow Jeff, beautiful work! What's the wood species and finish?

Thanks Andrew, definitely more modern than most of my work, but I enjoy a challenge every so often. That project presented a few challenges, applying the veneer to wrap down the side panel on a piece that large was fun!

The wood is Goncalo Alves, also known as Tiger Wood. I think I ended up using about 5 sheets of it and it runs about $400 a sheet.... pricey stuff! The finish is ML Campbel's Duravar in a sheen I dulled down a bit to be just shy of gloss. The finish is actually right off the gun, no work done after.

JeffD

[Jeff Duncan]

Hi Fellows,

Let me start off and say I don't want to hi jack this thread. I have one question about veneering and I did not want to start a new thread and a complete conversion. Hopefully one of you can give me an answer and that will be that.

I do veneering on occasion and this thread has been quite good to read. My question is I've never used paper backed veneer only raw or my own cut veneer. What do you use to put down paper backed veneer? I have to recover some veneered hollow core doors with mahogany veneer. I have my thoughts but would like to hear what all is used or available.

I hope not to cause this thread to go in another direction that was not my intention.

Thank you all
Ben

Hi Ben, I glue paper backed veneer mostly the same way I glue raw veneer and thats with yellow glue. All the veneer in the pics I posted earlier in the thread, (and it's all veneer), are paper backed veneer. If your buying full size veneer sheets its pretty common that they'll come paper backed. And the thickness of the veneer itself is no thinner than raw in my experience. No offense to anyone else's methods as there's always multiple ways to get it done, but I would never use contact cement for veneer. I know guys do and to each their own, its just something I wouldn't allow in my shop. For laminate yes, wood.... nope.

Now I'm wondering how your going to go about veneering a hollow core door? You won't be able to bag it as hollow core will just collapse. There are other methods of applying, but most of those require pressure of one sort or another.... and a hollow core door, (at least the somewhat modern ones), just doesn't have much strength on the face. I think it would be a challenge to get a good bond even on a flat press. I'm curious how your going to do it?

JeffD

[Joe Jensen]

I edge glue all my veneer before I vacuum bag it. I start with 1/16" as well. I use the epoxy veneer glue mentioned on the first page of this thread. I do glue both sides as the only time I had problem withe the veneer bonding I only glued the substrate.

[Osvaldo Cristo]

I make 1/16" shop sawn veneer, assemble panels in the usual with with veneer tape, and then glue it onto plywood, MDF, or particle board cores in a vacuum bag. By the time the panels are finish sanded I would estimate that the veneer is 0.050 - 0.060" thick. I've used Weldwood Plastic Resin Glue almost exclusively for at least years, but I also have used epoxy when I glued some to one side of Melamine after sanding off the coating. The MC of both the veneer and cores has always been between about 6% and 9% (30 - 55% RH), Winter to Summer in my heated, dehumidified basement shop. The temp. has always been at least 70F and I leave the panels in the press for 13 - 14 hours at roughly 20" Hg.
[...]

John

I have made some veneer applications at the last 25+ years and always used contact cement - consistently I had have great results, except for a single panel. I am not a frequent user of veneers but actually cement contact has been the single glue I have used for that application. It works.

[John TenEyck]

I have made some veneer applications at the last 25+ years and always used contact cement - consistently I had have great results, except for a single panel. I am not a frequent user of veneers but actually cement contact has been the single glue I have used for that application. It works.

I've used contact cement in special circumstances to glue commercial veneer to something. And I actually just used it to glue some shop sawn veneer, that I sanded down to 1/32" and then glued it to a Kraft paper backing with yellow glue, to Melamine. But I wouldn't consider it for gluing my normal 1/16" shop sawn veneer. Is that what you've had success with, or have you always used commercial veneer?

John

[Rhys Hurcombe]

Since you're state-side I won't recommend the product I use as it's not available outside of Australia from what I can tell (Techniglue 2:1 epoxy, very thick, tintable and glass hard when dry).

https://www.veneersupplies.com/ has some good info on their preferred glues. http://www.joewoodworker.com/veneering/faq-veneer-glue.htm

It's evident you're experiencing creep but whether it's creeping on the veneer side of the glue bond or the melamine side as a result of the veneer swelling/contracting, i'm not sure. I don't have any experience veneering onto melamine, either. So maybe I'm not much help at all. Recently veneered a large New Guinea Rosewood pivot door with 3mm veneers. Have done similar in the past, no issues yet and it's exposed to outside elements.

[Osvaldo Cristo]

I've used contact cement in special circumstances to glue commercial veneer to something. And I actually just used it to glue some shop sawn veneer, that I sanded down to 1/32" and then glued it to a Kraft paper backing with yellow glue, to Melamine. But I wouldn't consider it for gluing my normal 1/16" shop sawn veneer. Is that what you've had success with, or have you always used commercial veneer?

John

I have used commercial veneers only... but it looks it would work also for (slightly) thick veneers also. :rolleyes:

[Mel Fulks]

A tech guy for contact cement company told me the average life is 8 to 10 years. But he added it could last longer or fail
sooner. When it fails before being sent to job site the laminate guys don't ask tech guy what went wrong they just redo
with same stuff.

[John TenEyck]

Thanks Rhys. I just read joewoodworker's glue review this morning. Osvaldo, you might want to read it, too. He does not recommend the use of contact cement on anything other than paper back or 2ply veneer. He also does not recommend yellow glue, but some folks here have used it for years w/o problems. Anyway, after considering lots of options I'm either going to move to epoxy or Unibond 800. As I mentioned earlier, I started out using Unibond 800 but switched to PRG because I could get it locally and it's cheaper. Reading the literature on Unibond 800 again revealed that it does not require high pressure to bond well, and it only needs to be in the bag for 6 hours or so. PRG, yellow glue, even cold press glue, all are supposed to have 100 psi or higher to bond well. Epoxy doesn't need high pressure to bond well either, in fact, low pressure is better, perfect for use in a vacuum bag.

Rhys, I've had veneer splits not only on Melamine but also MDF and composite core (particle board). Never with anything other than ash veneer, however. From the photos I posted earlier, I'd says the failure has been between the ash and the glue, not the glue/substrate bond. All the more reason to move to a glue that better wets and wicks into the wood. Epoxy might just be the best overall choice.

John

[mreza Salav]

I've used PVA, contact cement (for paper back), and epoxy (WS) for veneering. For epoxy (whether it's veneering or not) I always apply the very thin glue to both surfaces and let it sit at least 5 minutes and then once the glue has thickened a bit apply it again to the joints.

[Alan Lightstone]

John:

I've usually used Unibond 800, with great success. No issues. Also had good success with Ultra-Cat PPR, which I usually just pick them up from Veneer supplies. I generally use that for shop-sawn veneers.

The majority of the veneer I work with is sapele, so open pored, and I've had no bleed through issues with those.

I have an easier time finding Ultra-Cat than Unibond.

[Osvaldo Cristo]

A tech guy for contact cement company told me the average life is 8 to 10 years. But he added it could last longer or fail
sooner. When it fails before being sent to job site the laminate guys don't ask tech guy what went wrong they just redo
with same stuff.

My glue ups are 25+ years and they are like new... except one that presented some gluing faults just one year or less after the construction...

[Mel Fulks]

Thanks, Osvaldo. Without your work the stats would be worse.

[Mike Henderson]

I don't use contact cement on anything that could be considered "heirloom furniture", just millwork applications that are likely to be replaced within 20 years.

Mike