Replies

1. 
   Robbie | May 10, 2004 11:04pm | #1

   Spitfire:  It is supposed to be good for exterior projects and for project where the joints may benefit from some volume filling effect.  Personally, I like epoxy for the former and better cut joints for the latter.

2. 
   AlbionWood | May 11, 2004 12:17am | #2

   Spitfire,

   All Polyurethane (PU) glues cure by reacting with moisture, and in the process they expand; if unconfined the glue will foam.  Gorilla foams a lot, some others less.  But the expanding/foaming action takes place fairly quickly and is all over in a few hours, so if anything is happening after that, there is something seriously wrong.

   My problem with Gorilla is, it doesn't seem to be very strong.  Edge joints will break right along the glue line.  I still use PU glues, but have to take extra care with joinery.  (I use them because they work a lot better and faster in my climate than PVA glue.)

   "Everything should be made as simple as possible, but no simpler."  A. Einstein

   http://www.albionworks.net

3. 
   WayneL5 | May 11, 2004 01:11am | #3

   You're showing your age with the movie reference!

   That's normal with polyurethane glues.  They should be used in tight joints and the joints must be clamped or the expansion will push the pieces apart.

   The advantages include longer working time than carpenter's glues, completely waterproof, sticks to non-porous materials like metals, and quite strong.  They are not strong if the joint is not tight and the space is filled with foam.  They also don't swell wood joints like carpenter's glues, so you maintain precise dimensions.  With carpenter's glues you can distort the piece and need to wait several days or more for the moisture to equilibrate before you can sand, if you want a really really flat surface.

   There are other glues which have these advantages, but I happen to like polyurethanes.

4. 
   BrianF | May 11, 2004 01:53am | #4

   I've used it several times for outdoor type projects. I have also learned to tape around the joints to make clean up a lot easier. Be sure to not get any on your fingers it can take a week or more to wear off.

1. 
   Biscardi | May 11, 2004 03:39am | #5

   Brian,

   I think your idea about taping along glue joints is a great idea. I did this recently for the first time using yellow glue. It made a big difference.

   Frank

5. 
   CStanford | May 11, 2004 02:16pm | #6

   It is of little use in making furniture for indoor use.  For these purposes, no glue is better than hide glue.

6. 
   LD | May 11, 2004 02:58pm | #7

   I use gorilla glue almost exclusively unless I need a short curing time.  It's an excellent glue for complicated glue ups due to it's open time.  Fine furniture or bird houses, it is my glue of choice.

   It is applied to one surface only, and in a thin layer.  Moisten the opposing side by wiping with a damp paper towel.  Clamp together for 3 to 4 hours and you won't have any glue failures.  It's easy to clean up the foam that oozes out of the joint with a chisel or scraper.  I usually finish the inside surfaces (including waxing) of the various parts before assembling, as gorilla doesn't stick well to waxed surfaces.

   Since the urethanes absorb moisture, you don't have the wood swelling around splines and biscuits like you get with PVAs, so no ghosts show up later.

   I haven't had any finishing problems with Gorilla like I seem to get frequently with PVA glues.  No matter how hard I try, I always seem to get some PVA on a visible side and I don't notice it until I wipe over it with a finish.

   I do use disposable plastic gloves during application, as any skin staining takes a few days to disappear.

   Dave

1. 
   JoeWood | May 11, 2004 04:42pm | #8

   Remember to use de-natured alcohol for clean-up before the glue sets up.

1. 
   LD | May 11, 2004 05:29pm | #11

   I use acetone if needed.  It will prevent skin discoloration if gotten to soon enough.

   Dave

2. 
   MatthewSchenker | May 11, 2004 04:53pm | #9

   Dave,

   Just to clarify one point in your post. Polyurethane glues (Gorilla glue) should NOT be used with biscuits. Biscuit joints fail with Gorilla glue, or any other polyurethane glue.

   I stopped using Gorilla glue because the advantages didn't seem worth it to me, and clean up is a total mess.

   For water-resistant joints -- Titebond II.

   For longer open times -- Titebond Extend.

   For fine furniture work -- liquid hide glue.

   I am no glue expert, but I have had great results from the above choices.

   I also recommend reading "The Glue Book," by William Tandy Young. This book will tell you all you need to know about the different types of glues and their properties and advantages. It's a great book. Amazon has it:

   http://www.amazon.com/exec/obidos/tg/detail/-/1561582220/qid=1084283527/sr=8-3/ref=sr_8_xs_ap_i3_xgl14/102-6017716-1056931?v=glance&s=books&n=507846

   I am just now starting to experiment with epoxies for complicated glue-ups.

1. 
   LD | May 11, 2004 05:27pm | #10

   Would you please reference your comment about not using urethane glues for biscuit joints.

   I've been doing this for years and never had a glue failure.  But I can always learn something.

   Dave

1. 
   Robbie | May 11, 2004 08:39pm | #14

   Dave:  I won't speak for Mathew. 

   However, polyurethane is not the best choice for biscuits.  Biscuits derive a portion of their strength from the biscuit swelling inside the joint.  This occurs when using regular carpenter's glue, ostensibly because of the water content in the glue allows absorption by the biscuit, resulting in it swelling.  Polyurethane and epoxy, for that matter, will not contribute to swelling of the biscuit.

1. 
   LD | May 11, 2004 10:03pm | #16

   I agree about the moisture issues and biscuits, but the swelling creates it's own problems as in ghosts later on.  A recent issue of "Woodworking at Home" demonstrated that particular problem.  They reported that is takes several days for the moisture in the area of the biscuit to come to equilibrium.

   I use biscuits for alignment not strength.  So if I'm gluing long fiber to long fiber, I don't need anything for strengthing, just an alignment aid.  If the biscuit fit is good, you do get some added strength by using them, but that is not the purpose.

   Anyway, I like the urethane glues, I have no finishing issues, no glue lines, and no complaints about failed joints.  I even use it for veneering.

   Don't get me wrong, I use PVA glues, liquid hide, white glue, and epoxies.  But what I have observed is that the urethane glues are hard to beat and have become my glue of chioce.  I think a lot of people try urethanes, using it just like PVA glues and then become concerned because it doesn't act like PVA glues.  So they reject it.  If you follow the directions, you will get an excellant joint with no future issues.

   Dave

2. 
   MatthewSchenker | May 11, 2004 09:36pm | #15

   As Robbie says in his post above, Gorilla glue is not good for biscuits because there is no moisture in it. However, you can see for yourself if you glue up a couple of biscuit joints. Do one with yellow glue and the other with Gorilla glue. When the joints are cured, whack each one with a malet.

   When you whack the Gorilla glue joint, you'll find that it just comes apart neatly with hardly even any splintering. The biscuits just come right out.

   When you whack the the yellow glue joint, it breaks apart, with chunks of wood fused to the biscuits.

3. 
   CStanford | May 11, 2004 06:48pm | #13

   If you're interested in an irreversible glue with customized open times then you need to use epoxy. 

   There is nothing that polyurethane glue does that another glue does not do better.

1. 
   AlbionWood | May 12, 2004 12:06am | #17

   I do think PU glue has some advantages:

   1.  No creep (as Titebond will sometimes do).  Glue lines stay invisible.

   2.  Easy cleanup.  The glue that foams out is easily pared off after it cures.  (One of the unique features of this stuff is that it doesn't stick very well unless clamped.  So when you pare off the cured glue, it doesn't tear off bits of wood with it, as epoxy will and PVA sometimes does.)  Cleaning up any glue squeeze-out is a pain, but this stuff seems a lot easier than most.

   3.  In my admittedly unusual environment - high humidity, low temperatures - PU performs very well.  PVA takes hours to set up and days to fully dry; PU is set in an hour.  Epoxy might work well too, but is a lot more trouble to mix and apply.  (Haven't tried hide glue yet - no glue pot or place to put one in the current quarters - but will soon.)

   The lone real disadvantage that I have seen is strength, especially of biscuited joints; I've broken them as the other poster described, and had to repair one bad joint.  But I also had a bad joint with PVA, so..."Everything should be made as simple as possible, but no simpler."  A. Einstein

   http://www.albionworks.net

1. 
   CStanford | May 12, 2004 01:41am | #18

   I don't like PVA that much either.  If I use an irreversible glue it's going to be epoxy, resorcinol, plastic resin, or something along those lines.

7. 
   PlaneWood | May 11, 2004 06:16pm | #12

   The only thing I use it for is gluing bricks together for the wife's flower beds.

   PlaneWood by Mike_in_Katy (maker of fine sawdust!)
   PlaneWood