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Thread: Cold creep in modified PVA glues?

  1. #46
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    Quote Originally Posted by Mark Bolton View Post
    This is something I am sure many here are especially tuned to. We spray nearly 100% waterborne finishes in the shop so its a daily issue. Nearly 100% is like 99.999985%. And using waterborne this sort of stuff rears its ugly head constantly and water grain raise is critical.

    Shops that plane a lot of material and no onboard sharpening, and you run your knives down a ways you will #1 develop a knick or knicks in your knives that will pound down the wood fibers at that knick as opposed to cutting. You will never see the issue. You can run the material through a widebelt or drum, sand with RO til your blue in the face. Take every pain in the world. Stain, and into the booth, and on the first coat of finish... poof. Up comes a perfectly straight planer mark. On any stained material that mark will appear as a light streak because the wood fibers when re-hydrated swell up and expose the raw wood below. Raw material its so obvious you can feel it with your hands and see it in low angle raking light.

    We will raise grain with water usually twice and sometimes more way before any material ever makes it to final sanding.

    Of course there could be an argument that water grain raise is contributing to what we think of as creep however agan there is no issue (or far less than perceptible) with TB original and Super. So my guess has always been that the practice of grain raising with water is a good one. Surface water on KD material is a zero issue for us. I also make it a practice to water-wipe most everything anyway in the event there is a rogue waterspot or something that will pop out on finishing. Thats an old trick from the construction days. You have a bunch of pine doors that may have been unloaded in a light sprinkle of rain or a passing shower. Sand them, hit them with stain, and the waterspots are out like a sore thumb and there is no way to get rid of them. Get in the habit of a water wipe on everything by default and you simply turn the entire door into a giant water spot and go on with your day.

    Im sure many here have read about issues with biscuits telegraphing through finish when using PVA and people leaving the biscuit slots unglued and only gluing the face of the boards as opposed to the NYW practice of brushing the biscuit slots and biscuits full of glue. The same issue would be true for Domino's. If the slot/biscuit/domino is close enough to the surface you could have a swelling/shrinkage issue there due to moisture in the glue an so on.
    Just to add to what Mark has outlined, the same hold true with strips prepared for laminations. If you planer is compressing these same marks, and you use waterbased glue, it can show up in the lamination, so again sponge and scrap/sand.

  2. #47
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    Quote Originally Posted by John TenEyck View Post
    Unibond 800 works great, especially in a vacuum bag where the pressures are low. Weldwood Plastic Resin Glue works well, too, but according to the instructions requires much higher pressures, higher than what you can get in a vacuum bag. I used to use mostly PRG because it was easy to obtain but I'm switching back to Unibond 800 after having a couple of bond failures with shop sawn veneer. But both products have essentially zero creep and I have used them for many bent laminations w/o problems.

    As far as the formaldehyde in both products, everyone has to decide for them self what risk they are willing to take. Gasoline has benzene, another known carcinogen, and most of us fill up the tank on our car, lawnmower, etc. w/o even thinking about it.

    John
    John, a vacuum bag at 25in of mercury exerts over 1800 lbs per sq ft. Much higher than anything other than a hydraulic press in an industrial setting.

  3. #48
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    True, but if you look at the literature for PRG you'll see that 1800 lbs/sq ft is not even close to what's needed for that product. That said, it does work ok in a vacuum bag as long as you apply at a rate of 35 sq ft /lb of resin instead of the recommended rate of 40 sq ft. At least that's what I found using shop sawn veneer.

    John

  4. #49
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    Not sure if itís been mentioned yet but there is a upside to using Pva glue for laminations.
    Its not very expensive and the glue doesnít damage your handtools and jointer knives.
    I learned my lesson with plastic resin glue on curved drawer fronts with half blind dovetails.
    My handsaw my jointer my chisels all took a hit from the glue.

    Itís not a easy thing to make a long thick table without glue lines.
    Theres so much to our craft thatís hard to put in words.
    Good Luck everyone
    Aj

  5. #50
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    I've been making fly fishing landing nets for several years to give as gifts and auction donations. Only used TBIII and now I am wondering if I should anticipate a call from a "former" BFF(Best Fishing Friend) that just lost a record Steelhead catch when my beautifully crafted net hoop delaminated!!
    Not familiar with Unibond and would appreciated suggestions on a more appropriated glue for this type of lamination. Thanks.

  6. #51
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    Quote Originally Posted by John C Bush View Post
    I've been making fly fishing landing nets for several years to give as gifts and auction donations. Only used TBIII and now I am wondering if I should anticipate a call from a "former" BFF(Best Fishing Friend) that just lost a record Steelhead catch when my beautifully crafted net hoop delaminated!!
    Not familiar with Unibond and would appreciated suggestions on a more appropriated glue for this type of lamination. Thanks.
    Sort of surprising TB III failed considering the ends of the laminations are tied together around the handle. There should be almost no stress on them.

    It doesn't take long to get familiar with Unibond 800. It should work well for this application, as should Weldwood Plastic Resin Glue, or Recorcinol, or epoxy. Google is your friend: https://www.vacupress.com/product/un...-liquid-resin/

    John

  7. #52
    Quote Originally Posted by John C Bush View Post
    I've been making fly fishing landing nets for several years to give as gifts and auction donations. Only used TBIII and now I am wondering if I should anticipate a call from a "former" BFF(Best Fishing Friend) that just lost a record Steelhead catch when my beautifully crafted net hoop delaminated!!
    Not familiar with Unibond and would appreciated suggestions on a more appropriated glue for this type of lamination. Thanks.
    I seriously doubt your net(s) will fail. Realize that Unibond is very toxic stuff and requires a respirator to use. While it has a vey rigid glue line, I personally would not go that direction unless absolutely required (some situations might be the absolute need for a very rigid glue line or for extended working time).

    Mike

  8. #53
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    Quote Originally Posted by Mike King View Post
    I seriously doubt your net(s) will fail. Realize that Unibond is very toxic stuff and requires a respirator to use. While it has a vey rigid glue line, I personally would not go that direction unless absolutely required (some situations might be the absolute need for a very rigid glue line or for extended working time).

    Mike
    Mike, you are entitled to your opinion, but to say that Unibond 800 is very toxic stuff far exceeds the actual hazard. Many of the products we use have risks. Following the manufacturer's PPE recommendations allows us to use them with minimal risk.

    John

  9. #54
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    I have used standard Titebond for countless bent laminations and have not noticed any creep or ill effect. I have used epoxy for that as well if the bent lamination was under greater stress or I needed more open time. Titebond III is simply not a glue I like; it has failed me more than once and I would never use it for bent lamination for sure.

  10. #55
    Quote Originally Posted by John C Bush View Post
    I've been making fly fishing landing nets for several years to give as gifts and auction donations. Only used TBIII and now I am wondering if I should anticipate a call from a "former" BFF(Best Fishing Friend) that just lost a record Steelhead catch when my beautifully crafted net hoop delaminated!!
    Not familiar with Unibond and would appreciated suggestions on a more appropriated glue for this type of lamination. Thanks.

    I would be surprised at a failure as well given normal use and the fact that a fishing net in my assumption would typically see intermittent use, a bound hoop, and likely has some serious varnish. That said, I would think in a serious wet environment epoxy all the way around would be a better solution. As John mentions the handle ends of the laminations in a net being bound eliminates a lot of the stress. As Ive stated before, your main concern would be someone tossing the item on the front seat of their truck or the rear deck of their car in the hot sun when then go in for a beer and a sandwich at lunch. You would potentially be able to separate the laminations by hand in that instance.

    I dont mean to beat the car thing to death but its the canary in the coal mine. Its no uncommon to make an item for someone and they pick it up at your shop and go run errands. You'd never think they'd lock it in their car in the hot sun, after all, its just a wood gee gaw. Well poof. Its dead. We have even made large furniture deliveries where we pull up with the box truck and the contractor or customer is going to leave them sit in a hot parking lot in full sun for "a while" til' their help arrives. Guaranteed death.
    Sometimes I just want to look at pretty pictures,... Thats when I go to the Turners Forum

  11. #56
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    Quote Originally Posted by Mark Bolton View Post
    I would be surprised at a failure as well given normal use and the fact that a fishing net in my assumption would typically see intermittent use, a bound hoop, and likely has some serious varnish. That said, I would think in a serious wet environment epoxy all the way around would be a better solution. As John mentions the handle ends of the laminations in a net being bound eliminates a lot of the stress. As Ive stated before, your main concern would be someone tossing the item on the front seat of their truck or the rear deck of their car in the hot sun when then go in for a beer and a sandwich at lunch. You would potentially be able to separate the laminations by hand in that instance.

    I dont mean to beat the car thing to death but its the canary in the coal mine. Its no uncommon to make an item for someone and they pick it up at your shop and go run errands. You'd never think they'd lock it in their car in the hot sun, after all, its just a wood gee gaw. Well poof. Its dead. We have even made large furniture deliveries where we pull up with the box truck and the contractor or customer is going to leave them sit in a hot parking lot in full sun for "a while" til' their help arrives. Guaranteed death.
    I had an interesting one last year.

    I built a veneered table, wedges from a central inlay out of Makore. I was curious as to how the finish was doing after a couple of years so I swung in the restaurant before they were open and all of the wedges were curled slightly at the joints. This confused me as the table was built using West and had been perfect through two seasons. About then a company painter that I knew from the install came in and I asked him when that had happened? He told me that the week before a hot water pipe had broken in the crawl below and as it was an instant heater had dumped hot water in the crawl all night. When they came in everything in the restaurant was dripping with water and the place was a steamy sauna.

    So... a couple of days later the designer I had worked with on this project calls me and tells me my table is failing never mentioning the broken pipe. I informed her that I knew the real reason and that it would not be taken care of at no charge, and that they should call the insurance company as the cost would be between $7-9K. The silence on the other end of the line was telling. I knew she was trying to con me, and you know how that makes one feel.

    I did not fix the table.
    Last edited by Larry Edgerton; 09-17-2019 at 7:48 AM.

  12. #57
    Quote Originally Posted by Larry Edgerton View Post
    I had an interesting one last year.

    I built a veneered table, wedges from a central inlay out of Makore. I was curious as to how the finish was doing after a couple of years so I swung in the restaurant before they were open and all of the wedges were curled slightly at the joints. This confused me as the table was built using West and had been perfect through two seasons. About then a company painter that I knew from the install came in and I asked him when that had happened? He told me that the week before a hot water pipe had broken in the crawl below and as it was an instant heater had dumped hot water in the crawl all night. When they came in everything in the restaurant was dripping with water and the place was a steamy sauna.

    So... a couple of days later the designer I had worked with on this project calls me and tells me my table is failing never mentioning the broken pipe. I informed her that I knew the real reason and that it would not be taken care of at no charge, and that they should call the insurance company as the cost would be between $7-9K. The silence on the other end of the line was telling. I knew she was trying to con me, and you know how that makes one feel.

    I did not fix the table.
    Now that type of luck makes you believe in a god.
    Sometimes I just want to look at pretty pictures,... Thats when I go to the Turners Forum

  13. #58
    That's not luck - that's diligence - Larry cared enough to check up on his work and it paid off for a change.

  14. #59
    Quote Originally Posted by Bradley Gray View Post
    That's not luck - that's diligence - Larry cared enough to check up on his work and it paid off for a change.
    Im guessing the vast majority of us check on our work periodically. The luck I was referring to was with regards to the timing of the visit combined with the fortune of running into another sub and getting the lowdown on what happened. 100% agree with regards to a scenario like that working out in the makers favor.
    Sometimes I just want to look at pretty pictures,... Thats when I go to the Turners Forum

  15. #60
    Im guessing the vast majority of us check on our work periodically. The luck I was referring to was with regards to the timing of the visit combined with the fortune of running into another sub and getting the lowdown on what happened. 100% agree with regards to a scenario like that working out in the makers favor.
    I love it when the good guys win one!

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