Glue dissapointment

[40deluxecoupe]

I have been using a polyeurethane glue during the build of my T/D. I was suspicious of the bonding between my sides, which are 3/4" form ply and pine timber which is in turn glued and screwed to the rear bulkhead. After leaving it several days I unscrewed one piece and lightly tapped the pine timber with a hammer, two taps and it came off. I thought the problem was that my form ply has a dark smooth coating applied to it and I guess it needed to be sanded before applying the glue. Just to check I then glued two off cuts of pine and left them clamped over night. The bond between the two was easily parted. Of course when all else fails, its time to read the instructions. They note that when using this glue one surface has to be rubbed with a damp cloth, 1 minute before glueing, I find this strange, but will post tomorrow after I check my lastest experiment.
So its been 1 step forward, 3 steps back this week.
Any comments.
Thx.

[IraRat]

I used the Elmers poly glue, and yes, you're so supposed to wet one side. But I can't believe that even if you didn't, that it would come apart THAT easily.

You bought this glue recently? I think I remember hearing that it doesn't have a long shelf life.

[toypusher]

I used the Elmers poly glue, and yes, you're so supposed to wet one side. But I can't believe that even if you didn't, that it would come apart THAT easily.

You bought this glue recently? I think I remember hearing that it doesn't have a long shelf life.

Ira,

Just think of how easy it is to scrape the stuff off of an area that was not wet when the glue went on it. Like when it squeezes out and you have to clean up later. If the surface was not wet, then the glue would just scrape right off when it dried. I spilled some on my concrete floor and the floor was dry. When it dried, I went scrape it off and it was bearly stuck and came away pretty clean.

Kerry

[Geron]

I talked with a TD manufacturer who said that he glued nothing. Idea was that if a corner got damaged and the TD returned repairs were easier. Stated that he'd never had a problem with not gluing. Used GE silicone II on all joints which breaks apart easier.

I Glued the heck out of mine using PL polyurethane construction glue.

Geron

[madjack]

...40, 2 things,
1rst, if by form ply, you mean ply meant to build forms for concrete, well it has a wax impregnated coating to stop it from sticking to the concrete and will certainly not glue up very well.
2nd, poly glues are water activated and with out the dampness to activate the glue it will not bond properly.
I have bonded metal to glass, wood to wood, urethaned wood to aluminum all with no problems, if used properly and allowed to cure(3/4hrs) I have found it to be an excellent product
madjack

[GeorgeT]

yep, tried soma dat glue widdout da watuh an' no dang good. Wid da watuh, purty dang good!

[asianflava]

This is some good info, I guess the same goes for Gorilla Glue. The impression I got was that you could wet the surfaces but it wasn't required. Sounds like you have to for a good bond.

[toypusher]

Guys --- R.T F. I.

[An Ol Timer]

Madjack said

2nd, poly glues are water activated and with out the dampness to activate the glue it will not bond properly.

Not entirely true, some are, some aren't! Gorilla Glue , yes. PL poly, No.

I have used PL poly on boats, kayaks and on my tear, NO WATER!

[An Ol Timer]

I probably should follow up with the one thing that we have a tendency to do, that being once we find a product we like, it becomes our everything product. In building a project of any type we should be using several different glues to match the job that is being done. At present I have used 3 different glues and will, by the time I get finished, have used 3 different finishes for my surfaces.

[asianflava]

I've got you beat, on this project alone I've used:

Epoxy thickened with microfibers for laminating the sidewalls and floor
Titebond II for laminating the cabinets and bulkheads and sidewall frames
Liquid nails to glue the sidewalls to the floor, not satisified with this stuff
Gorilla Glue to glue the roof and ceiling to the spars
PL Polyurethane caulk to glue the insulation to the roof bays

[An Ol Timer]

It would be nice to have a chart listing several parameters of each glue type with such things as, how easy to use, curing time, holding power, cost, cautions in using, etc. There is such a wide range of glues available, that for someone new, it can be overwhelming just to make a choice.

[Chris C]

I don't know if anyone will listen, but I make my living building custom furniture and I'd sure like to talk all of you out of using polyurethane glue. It's only plus is resistance against moisture. It doesn't hold nearly as well as regular Titebond or any other woodworkers glue. If your joints don't fit, it won't bridge the gap and hold it. (some people think since it expands it will make up for poor fitting joints...............not so!) Don't get me wrong, it's mighty sticky stuff and when joints fit well, it does a decent job. But it's not nearly as strong a bond as regular woodworking glues. If you have a poor fitting joint, use epoxy.............it's the ONLY means of filling gaps and bonding strongly.

Now I'll go duck behind the desk while all the users of polyurethane glues throw rocks at me.

[TomS]

So far on my project, I've used the following adhesives:

1. Gorilla glue for building cabinet frames and other sub assemblies that will be covered up or sanded prior to installation.

2. Titebond III around finished surfaces since I can easily clean up any drips with a wet rag.

3. PL Polyurethane construction adhesive for the main structural areas such as mounting roof spars or or attaching sidewalls to the floor frame.

If Titebond is indeed stronger, why put up with mess from the other two products?

BTW -- The polyurethane glue users would like to throw rocks at you. But they can't. The rocks keep sticking to thier fingers.

[Chris C]

Sorry.................."just stating the facts, Ma'm, just the facts."