Results 1 to 31 of 31

Thread: Polyurethane glue or epoxy?

  1. #1
    Join Date
    Aug 2015
    Location
    Stavanger, Norway
    Posts
    104

    Default Polyurethane glue or epoxy?

    I have read about using one-component polyurethane glue instead of two-component epoxy. Adrian Morgan has used Collano Semparoc for building an Oughtred Elfyn in Vendia. I am also in contact with a builder who has used Soudal Purocol with plywood. Does anobody know how these two products compare?

    Will a one component glue replace epoxy?

    Best regards,

    Erik
    Last edited by kleppar; 02-25-2018 at 03:24 AM.

  2. #2
    Join Date
    Dec 2003
    Location
    Portland, Oregon
    Posts
    47,882

    Default Re: Polyurethane glue or epoxy?

    Do not know the product you mention.

    But it it's a foaming polyurethane (introduced as Gorilla Glue here)... then stay clear.

    If it's a thicker, caulking-style (comes in a tube and dispensed thru a caulking gun)... than it's appropriate for some applications, but not all, and requires some adjustment in technique. You'll want to read up on it a good bit before committing.

    Another 1-part option you didn't mention. Can you get a Type III PVA (polyvinyl acetate) where you are. Here it's 'Titebond III' or similar from Elmer's (Bordon) and others. A perfectly fine substitute for epoxy... IF your joinery will be tight, and clamps applied well. One reason amateur boatbuilders especially use epoxy is that less-than-perfect joiner becomes meaningless (or even a benefit) instead of a serious problem.
    David G
    Harbor Woodworks
    http://www.harborwoodworking.com/boat.html

    "It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)

  3. #3
    Join Date
    Nov 2011
    Posts
    5,213

    Default Re: Polyurethane glue or epoxy?

    You should also keep in mind that TIII recommends that it not be used below the waterline. I've experimented with that and found that it worked fine, but there you have it. Joinery is critical with TIII, it's not at all gap filling.

  4. #4
    Join Date
    Oct 2009
    Location
    South Puget Sound/summer Eastern carib./winter
    Posts
    14,832

    Default Re: Polyurethane glue or epoxy?

    Trying to fix what is not broke.
    Why do folks use these alternative adhesives....is it to save the nickel?

  5. #5
    Join Date
    Dec 2003
    Location
    Portland, Oregon
    Posts
    47,882

    Default Re: Polyurethane glue or epoxy?

    Quote Originally Posted by wizbang 13 View Post
    Trying to fix what is not broke.
    Why do folks use these alternative adhesives....is it to save the nickel?
    Yes, that question occurred to me also.

    kleppar - you didn't say - why are you trying to avoid epoxy?
    David G
    Harbor Woodworks
    http://www.harborwoodworking.com/boat.html

    "It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)

  6. #6
    Join Date
    Dec 2016
    Location
    EU
    Posts
    300

    Default Re: Polyurethane glue or epoxy?

    Probably for convenience. Epoxy is still the cheapest glue if one does not buy big names. And it all depends where you use it. Strip planking or plywood with chine logs and screws probably.

  7. #7
    Join Date
    Nov 2016
    Location
    Kingsville, Ontario
    Posts
    221

    Default Re: Polyurethane glue or epoxy?

    Possibly for availability

  8. #8
    Join Date
    Dec 1999
    Location
    Oriental, NC USA
    Posts
    4,624

    Default Re: Polyurethane glue or epoxy?

    When I've checked, polyurethane has always been more expensive than the epoxies most boatbuilders use. Polyurethane also has a short shelf life while unmixed epoxy lasts a looong time. There is always someone trying to promote a glue other than epoxy but, the consensus remains that while epoxy may not be perfect, its very good for just about all boatbuilding uses.

    One issue is that there are literally hundreds of different formulations of epoxy tailored to specific applications, particularly in industrial uses. This could be daunting if a beginner gets involved in those. Its pretty simple if you just follow the information available from the manufacturers. Some, like Gougeon, System 3, RAKA and MAS have plenty of detailed instructions. Most problems are the result of just not reading the instructions.
    Tom L

  9. #9
    Join Date
    Jan 2004
    Location
    Norwich,United Kingdom
    Posts
    5,532

    Default Re: Polyurethane glue or epoxy?

    I have used European polyurethane glues for years.Not for situations where the wood is constantly immersed admittedly,but one of my earliest jobs was a teak framed hatch that has lived outside for more than twenty years continuously with no problem.Be sure to use one that can achieve bonds that conform to the D4 durability specification.The much faster cure time is also useful.

  10. #10
    Join Date
    Jan 2000
    Location
    Portland, Maine
    Posts
    16,411

    Default Re: Polyurethane glue or epoxy?

    We’ve had forum members build glued lapstrake plywood boats successfully with PL Premium polyurethane glue. The products listed in the op are not sold in the US.

  11. #11
    Join Date
    Jul 2011
    Location
    Lindstrom, MN
    Posts
    2,089

    Default Re: Polyurethane glue or epoxy?

    Will a one component glue replace epoxy?
    No. It may work well enough to be used a an alternative to epoxy in some specific applications, and may be preferable to epoxy in a few applications.

    Most of us are in the US, so we don't have access to the same adhesives. From what I can find, both Soudal Purocol and Collano Semparoc are similar to Gorilla glue in that they are moisture curing polyurethanes that foam as they cure. Foaming PU has a bad reputation on this forum due to low strength in loose joints. The European foaming glues seem to have a more favorable reputation on other forums.

    This test shows that a foaming glue can be very weak in a loose joint and reasonably strong in a tight joint:
    http://www.oldbrownglue.com/images/a...urGlue_FWW.pdf
    Woodgears found that the Gorilla glue fared better in his test, but he only tested tight joints.
    https://woodgears.ca/joint_strength/glue.html

    Collano Semaprox apparently does not foam as much and is consequently a better adhesive than Gorilla glue. This was stated on one forum, so it is hard to say for certain that it was a typical result. I did not find enough information about Soudal Purocol to compare. This may be the article that you referred to: http://intheboatshed.net/2014/03/15/...ane-wood-glue/

    There is some useful information in these links, but no answer as to how the two glues in question compare:
    http://www.woodcentral.com/cgi-bin/r...cles_737.shtml
    http://www.robbins.co.uk/Pdf%20Files...20Semparoc.pdf
    http://www.marinechandlery.com/colla...od-glue-800ge/
    http://lumberjocks.com/shipwright/blog/series/4499
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  12. #12
    Join Date
    Jan 2010
    Location
    Northern Europe
    Posts
    9,074

    Default Re: Polyurethane glue or epoxy?

    You may as well call PU a "joiners glue". It was never designed as structural a gap filling adhesive. It works fine if the joints are tight, and if you work in a damp, unheated workshop. I use both, but never the US gorilla brand.

  13. #13
    Join Date
    Oct 2013
    Location
    dfw
    Posts
    1,119

    Default Re: Polyurethane glue or epoxy?

    kleppar, "I have read", "I heard", "so n so said", "I found on the internet"... a plethora of reports/stories... that you can build boats with lesser/more readily available bonding/fairing agents such as Tite-Bond lll and PL Premium (here in the US) glues to build small wooden/plywooden boats instead of using what has become the goto agent which is epoxy

    SO I decided to do a test build to see just how different a project would be when using 3 different agents to build 3 boats of the same design

    The boat I chose is the Mini MouseBoat designed by Gavin Atkin, an 8 footer specifically intended for youth or small adults(<200#)

    atkin's mini mouse boats

    At Farley Boat Works I have been involved in 2 youth workshops where epoxy was the primary bonding agent used so I decided to personally build 2 more, one using PL Premium & the other using Tite-Bond lll and other materials commonly found at big box stores

    Boat #1 which was built with Tite-Bond lll, was deivered to the Boat Works just before Harvey made his appearance, survived the storm w/ no visible damage and will be used for demonstration and youth activities

    Boat #2 which was constructed using PL Premium is in her finishing stages and will be delivered soon(I hope in time for the Wooden Boat Festival in April)

    Long story short I have confirmed the rumors that alternate products will work in simple builds BUTT what you may gain/save in cost advantage will bite you in the time element butt

    The additional time required for curing/clean up/fairing times between steps/stages of your build will consume a lot more of your time than with epoxy

    Both Tite-Bond lll & PL Premium will require addional calking/fairing products even if you are only going for a utility finish

    Epoxy can be your single product only requiring a thickening agent(I'm beginning to enjoy using wood flour) and if you really want to go exotic get different speed hardeners to suit your perceived needs

    In my personal shop/barn, I like slow and tropical slow epoxy hardeners due to my "old man" speed of working

    Tite-bond lll requires much more accurate joinery since it has NO GAP FILLING QUALITIES and even shrinks a bit during it's cure

    PL Premium does expand during it's curing process which can fill some imperfections in joinery butt the darn stuff keeps oozing for hours(over night)

    Epoxy on the other hand does have gap filling qualities that even strengthen the joint when there are imperfections which get filled with the thickened product and it doesn't shrink or expand measurably during the cure


    When using metalic fasteners in the process they will hold an epoxy joint while other opperations are going on

    Even when using metalic fasteners the extended cure times and idiosyncrasies of the other two bonding agents will require a considerable amount of additional time before continuing the build

    In my experience, the Mini MouseBoat can be completed with a utility finish and in the water in 4 1/2 days of working using Junior High aged labor when epoxy is the primary bonding agent

    Building the same boat using alternate bonding agents pushes the build time out exponentially

    If you intend to use fibergass in any part of your build you will be buying epoxy anyway so why not just use one product and be done with it

    BTW, if you are having any thoughts of a bright finish IMO epoxy is the only way to go since the other types of glues don't play well with stains & clear finishes

    If you care to wade thru my thread, with lotsa pics/documentation, on this issue you can goto the Mini Mouseboat(s) Winter Build which has turned into an over a year build, in part due to side trips/projects and a little wind storm

    http://forum.woodenboat.com/showthre...)-winter-build

    GOOD LUCK WITH YOUR QUEST

    Hasta

    sw
    "we are the people, our parents warned us about" (jb)

    steve

  14. #14
    Join Date
    May 2009
    Location
    Fort Worth, Texas, USA
    Posts
    2,099

    Default Re: Polyurethane glue or epoxy?

    Now that was some useful first hand experience with some specifics.
    Thanks for writing it up.

  15. #15
    Join Date
    Oct 2013
    Location
    dfw
    Posts
    1,119

    Default Re: Polyurethane glue or epoxy?

    You're Welcome, upchurchmr

    I also heard one can build a STICH N TAPE version of a cousin of the Mini MouseBoat which is simply a stretched version of the ORIGINAL MOUSEBOAT :-O

    The ORIGINAL MOUSEBOAT is a V-BOTTOMED boat of virtually the same dimensions as the ones I am test building

    "they say", some have built the 12 footer using DUCT TAPE for the stitching and a meshed SHEET ROCK TAPE & PL PREMIUM for the taping :-O :-O

    I shant begin to expound on this method until I've done or at least started one myself

    I do know I'll wait for WARM WEATHER before dropping ole LARDUSS BOTTOMUSS MAXIMUSS in anything fashioned in that manner with those materials ;-)

    In the event I do tackle that build I WILL POST A THREAD to document the entire process

    Butt 1st I've got several projects on the stove top needing finishing

    Until then...

    Hasta

    sw
    "we are the people, our parents warned us about" (jb)

    steve

  16. #16
    Join Date
    Jan 2011
    Location
    Norwalk CT
    Posts
    929

    Default Re: Polyurethane glue or epoxy?

    Do the search thing for an old Bob Smalser thread titled "Are your glue joints repairable".

  17. #17
    Join Date
    Dec 2015
    Location
    Dorset, UK
    Posts
    821

    Default Re: Polyurethane glue or epoxy?

    Most glues are 'strong enough' at the start, the difference is how they diminish with cyclical loading.

    All studies show that Resorcinol retains it longest > Epoxy > Polyurethane.

    Whether cyclical loading is going to be relavent with what and how you are gluing things together on your project is for you to decide.

  18. #18
    Join Date
    Dec 1999
    Location
    Oriental, NC USA
    Posts
    4,624

    Default Re: Polyurethane glue or epoxy?

    Quote Originally Posted by willin woodworks View Post
    Do the search thing for an old Bob Smalser thread titled "Are your glue joints repairable".
    Bob's goodies here: http://contrib1.wkfinetools.com/bSma...lser-index.asp
    Tom L

  19. #19
    Join Date
    Aug 2013
    Location
    S.W. Florida
    Posts
    3,564

    Default Re: Polyurethane glue or epoxy?

    Quote Originally Posted by Tom Lathrop View Post
    Great link, TL; thanks.

    Hope the voyage is a long one.
    May there be many a summer morning when,
    with what pleasure, what joy,
    you come into harbors seen for the first time...

    Ithaka, by Cavafy
    (Keeley - Sherrard translation)

  20. #20
    Join Date
    Jul 2009
    Location
    Zbigit
    Posts
    1,174

    Default Re: Polyurethane glue or epoxy?

    As part of my rudder-making experiment, I made an emergency rudder "for practice". Besides, to do the event I want to do in 2020, I have to have an emergency rudder setup, so I figured I might as well make one.


    The strips of redwood that make up the core of that rudder were glued with PL Premium.

    Here's an offcut from the emergency rudder that I tried to torque apart - redwood-glue'd up with with PL Preminum polyurethane adhesive. You'll note that the wood broke before the joint gave up. Admittedly, it broke near a knot. However, I physically could not break the other parts of this offcut with my bare hands and I'm a pretty strong dude. The bonding surfaces that I could not break are about 1.5 inch by 1.5 inch.



  21. #21
    Join Date
    Oct 2009
    Location
    South Puget Sound/summer Eastern carib./winter
    Posts
    14,832

    Default Re: Polyurethane glue or epoxy?

    ^ I hope your emergency is in calm water!

  22. #22
    Join Date
    Jul 2009
    Location
    Zbigit
    Posts
    1,174

    Default Re: Polyurethane glue or epoxy?

    Quote Originally Posted by wizbang 13 View Post
    ^ I hope your emergency is in calm water!
    wizbang13, that rudder is also encased in 19 ounce triaxial fiberglass in epoxy. The boxy, "not-foil-shaped" top of the rudder will sit in a cassette mostly from plywood and hardwood but also wrapped in linear carbon fiber. The cassette hangs off of the pintles, on the transom.

    Personally, I'm quite convinced that the rudder is pretty damn strong. Seeing as I can clamp it to a table with half of the rudder hanging off, and then I can sit on it, all 300 pounds of me, I'm pretty confident in it despite your comment.

  23. #23
    Join Date
    Aug 2009
    Location
    Olympia, WA, USA
    Posts
    1,996

    Default Re: Polyurethane glue or epoxy?

    Why do folks use these alternative adhesives....is it to save the nickel?
    Some people have serious allergies/sensitivities to epoxy. This is one reason why the guy who built my boat (Ralph Stanley) wouldn't use epoxy (his son later joined the shop and would do the epoxy work), and, from my understanding, why John Guzzwell won't use epoxy.

    John used to use resorcinol, and more recently has shifted to a Borden product that was the precursor to TB-III, and when I spoke with him for advice he spoke quite highly of TB-III. Both above and below the water --though he may have someone come in and sheath the boat in glass once he's done with the woodworking; I'm not sure, but I've gotten hints of that. I believe, however, that he uses TB-III for his (unsheathed) spars.

    I used resorcinol, rather than epoxy, for Bucephalus's cold-molded deck because I knew the deck would be getting quite warm, with the grey paint I use. Epoxy does *not* like heat, as we all know --it takes surprisingly low temperature to weaken it-- and the folks at West were professional enough to warn me that cyclic (e.g. diurnal) heating *does* weaken epoxy over time, and to suggest caution in my project. (This, incidentally, is part of why epoxy is NOT an architecturally rated adhesive.) Therefore I used resorcinol, which loves heat.

    There are a lot of excellent adhesives out there. The trick to getting the best of each of them is playing to their strengths and knowing and avoiding their weaknesses. PU isn't gap-filling; nor are PVA or resorcinol. All of those want tight joinery and high clamp pressures, two have short open times, and the third is very fussy about its (high) cure temperature. Epoxy tolerates gappy joinery and is very obliging with its open time, but it can't take heat.

    I hope the OP finds a good adhesive for his needs.

    Alex

  24. #24
    Join Date
    Jul 2015
    Location
    Frenchman's Cove, Newfoundland and Labrador, Canada
    Posts
    211

    Default Re: Polyurethane glue or epoxy?

    I have a few data points that may be relevant here.

    I know of a fellow building dog sleds who laminates the curved hardwood runners (mostly ash) with gorilla glue. I've also used it to laminate a splint onto a broken runner (backed up with stainless through bolts) and a friend of mine did something similar, but without the bolts, with a little kicksled. The kicksled has seen a winter's hard use, and my freight sled less, but either with a load of camping gear or a rider in the basket. Neither of them has failed yet.

    These dog sled runners are subjected to extreme repeated flexing and bumping as they ride over moguls and ice crusts at 10 to 20 mph. Often the driver's weight is all on one leg while working the brake with the other; this really concentrates the stress. Probably way more stress than the joints between plywood planks in a boat will ever be subjected to, at least if these planks are also joined to frames every few feet. All assuming we are talking about a small boat here, on the scale of the Elfyn mentioned in the op.

    I once (very foolishly) tried plywood filleting and taping with drywall tape and PL Premium type of polyurethane. BAD idea!!! Without there being clamping pressure the stuff bubbled up (not as much as Gorilla glue, but enough). I spent forever chiseling off the bubbles and faired over top of it with thickened epoxy and "real" fiberglass cloth. There is just nothing like learning things the hard way.

    I can vouch for the woodgears.ca guy whose site was linked to in post #11 by MN Dave. His name is Matthias Wandel and he was my classmate in Grade 8 and High School. He is absolutely brilliant and made his money in computer programming; this woodgears thing is his "retirement project" which he probably started before age 45. I've personally seen one of his wooden bandsaws and several really creative jigs that he designed. Unfortunately he didn't test any of the boatbuilding epoxies.

  25. #25
    Join Date
    Feb 2005
    Location
    Norway
    Posts
    194

    Default Re: Polyurethane glue or epoxy?

    Epoxy is stronger.

  26. #26
    Join Date
    Apr 2000
    Location
    Barrie, Ontario, Canada
    Posts
    4,701

    Default Re: Polyurethane glue or epoxy?

    I use Bulldog PL Premium in places where it's a glue-and-screw joint. Or nail and screw.

    The cartridge-gun tubes are pretty cheap at the big-box stores.

    Never had a problem in the last 3 small boats.

    For critical joints where there are no metal fasteners, like scarf joints in plywood, I use epoxy.

    Dave

  27. #27
    Join Date
    Jan 2008
    Location
    Lake Champlain, Vermont
    Posts
    2,600

    Default Re: Polyurethane glue or epoxy?

    In my experience pl premium is stronger than the joint. Wood tears apart before joint fails.I would still used epoxy on joints that are to be filleted and taped.

  28. #28
    Join Date
    Aug 2015
    Location
    Stavanger, Norway
    Posts
    104

    Default Re: Polyurethane glue or epoxy?

    Thanks a lot for excellent feedback - I just received drawings for building an Oughtred Elfyn, and Iain himself likes Collano Semparoc, for its good cap-filling properties. For your interest, I may build this in Vendia.

  29. #29
    Join Date
    Jun 2006
    Location
    Blacksburg, VA
    Posts
    399

    Default Re: Polyurethane glue or epoxy?

    One should keep in mind the fundamental difference between one-part and two-part adhesives. In one sense, the only true one-part adhesives are hot-melt glues. In two-part adhesives both reactants needed to form the final polymer are included in the mix. In so-called one-part adhesives one reactant comes from the jar or tube, while the other comes from the environment.

    In a two-part adhesive, like epoxy, everything needed to form the final polymer is included in the mix. No mass transfer between the environment and the mix is required. Epoxy can be very thick and still set up nicely. The only limit is that really thick pieces of fast-setting epoxy can overheat as they set up.

    One-part adhesives need contact with something in the environment. For most it is oxygen, for some water. That oxygen or water has to penetrate the adhesive. No problem for a thin layer, but when you get a thick layer the necessary reactant has trouble getting to the middle. This can lead to slow or inadequate setup. It can also lead to strains as the material shrinks or expands as it sets up (like thick paint alligatoring when the surface dries while the the underneath is still liquid.

    With a two-part adhesive you have control over the mix of two reactants, while with a one-part adhesive the shape and tightness of the joint play a big part in the mixing of the adhesive and the reactant from the environment.
    I will beg you for advice, your reply will be concise, and I will listen very nicely and then go out and do exactly what I want! (Apologies to Lerner and Lowe.)

  30. #30
    Join Date
    Jul 2005
    Location
    australia
    Posts
    25

    Default Re: Polyurethane glue or epoxy?

    With the water-curing polyurethane adhesives I have used,including Sika's "SikaBond Techgrip" here in Australia,the instructions say to spray both gluing surfaces shortly before applying & spreading the adhesive & clamping till cured.This ensures the adhesive is in contact with sufficient water to cause the curing reaction.I regularly do test pieces when doing big glue-ups & they have always been very strong & failed in the wood, not the joint.

    Some people might be put off by the softness of fully cured foam that has escaped from the joint.Don't.I can assure you,if take the clamps off shortly after the curing begins & excess foam is squeezing out,it is extremely difficult to separate the pieces being glued.This stuff is tenacious & properly clamped produces an excellent bond.

    These products are often sold in handy 500gm squeeze bottles so buy a bottle & make up some test pieces if you are unsure about using it....read the instructions first of course.

    I use epoxy for primary structures & polyurethane for much of the rest of the boat, especially solid mast & spars, none of which has ever had a join open.It is messy to work with & less suitable than epoxy in some applications for that reason.
    Last edited by ausie; 02-25-2018 at 11:25 PM.

  31. #31
    Join Date
    Aug 2013
    Location
    Valnesfjord, Norway
    Posts
    816

    Default Re: Polyurethane glue or epoxy?

    Hope you make a thread building Elfyn,,,

    btw. Why not solid wood and copper? there must be some leftover oak after the building of Draken in Haugesund?

    Skål!

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •