T-88/Titebond lll

[grdev]

I glued several wood samples using both T-88 and Titebond lll on both Doug Fir , Spruce and Pine. I left them to cure for two weeks and the Titebond consistently  pulled more wood fibers of the adjoin piece than the T-88 when I broke them apart.
I will be using Titebond lll for my spar webs and the rest of my wing.

[Steve]

I glued several wood samples using both T-88 and Titebond lll on both Doug Fir , Spruce and Pine. I left them to cure for two weeks and the Titebond consistently  pulled more wood fibers of the adjoin piece than the T-88 when I broke them apart.
I will be using Titebond lll for my spar webs and the rest of my wing.

Gil:
I repaired with Titebond III a delaminating maple cutting board made of strips that was put back in service and washed off with water several times a week... It started showing stress at the joints soon and in 3 months was delaminating again at the glue lines...
Steve

[grdev]

Steve, I did everything the directions called for with the T-88 and when I glued the samples I clamped them with different pressures and they all came out pretty much the same. They broke right at the glue line and did not penetrate the wood surfaces very much at all. Maybe I have a bad batch of T-88. Maybe I should heat  the glue first, but it was applied and stored well above 70 degrees.  All of the samples I did with the Titebond  lll, clamping the same way I did the T-88 all pulled wood fiber from the two pieces of wood.
The T-88 did set up rock hard as did the Titebond. 
Now I have to ponder which to use. Have you ran samples? Talking to Leonard last week he told me he was happy with Titebond and also uses it.  If you seal your wood properly with spar varnish don't you agree it should be OK? I would like to see someone else make some samples and see if they have similar results to what I found. T-88 is a bit pricey ,  but then on the other hand I don't want my wing to come apart in flight.

[Steve]

Steve, I did everything the directions called for with the T-88 and when I glued the samples I clamped them with different pressures and they all came out pretty much the same. They broke right at the glue line and did not penetrate the wood surfaces very much at all. Maybe I have a bad batch of T-88. Maybe I should heat  the glue first, but it was applied and stored well above 70 degrees.  All of the samples I did with the Titebond  lll, clamping the same way I did the T-88 all pulled wood fiber from the two pieces of wood.
The T-88 did set up rock hard as did the Titebond.  
Now I have to ponder which to use. Have you ran samples? Talking to Leonard last week he told me he was happy with Titebond and also uses it.  If you seal your wood properly with spar varnish don't you agree it should be OK? I would like to see someone else make some samples and see if they have similar results to what I found. T-88 is a bit pricey ,  but then on the other hand I don't want my wing to come apart in flight.

I'm venturing a guess about the DF Flooring - It's been treated: http://www.dougfirflooring.com/blog/tag/douglas-fir-porch-decking/  If you must use it don't glue it with T-88 - the testing you have done proves T-88 doesn't penetrate the cell structure...

[grdev]

The DF I'm using certainly looks virgin, not treated with anything. I will try my T-88 on some Sitka Spruce scraps I have as well as some Poplar and some plywood.  I took some DF samples to Leonard to look at, but maybe he only looked at the grain, which he said was fine.
How deep should the T-88 penetrate? The directions say to be careful not to use to much clamping force as you will squeeze out the glue.

[riorex2002]

just to muddy up the water a bit,i found a test piece using gorilla glue on if i remember correctly,spruce,that i had not brocken,in my junk i was clearing out prior to starting my L/E.this must have been glued well over ten years ago.and when i broke it ,all the wood splintered the glue line was intact.i started using this glue after learning that wooden boat builders use this on under water parts..Have never had any trouble with this product as long as you can clamp it well  and the joint does not have any gaps.It is useless at filling gaps plus you must damp the area first.i know this does not solve your problem but is just another thing to think about
Rex

[Richfroh]

I used T-88 to glue my ribs and spars. I glued up test samples with every batch of glue I made. They were broken apart and every sample broke the wood not the glue joint. I did not try Titebond.
Rich

[grdev]

I've had good results with T-88 in the past. That is what I used mainly on my DE. This is why I'm a bit puzzled as to why my glue samples are now failing. I bought this T-88 from Amazon.com, maybe it is just old glue.

[grdev]

I found this information on the T-88 web site:
Product Application Douglas Fir
Because of resinous nature DF trends to extrude minute amounts of material which may act as a weak inter layer when adhesive is applied. Sand with 60-100 grit abrasive and thoroughly remove sanding debris. apply adhesive with in 48 hours.

I'll try this and see if I have better results.

[grdev]

Last night I took a 1" x 3/4" x 3" block of Doug Fir. sanded one side with 80 grit sand paper, wiped all the residue off as best I could and glued it to a piece of pine board and let it stand for 24 hours. I had a hell of a time breaking the wood apart, it split right down the middle of the DF block, no glue problems here. Just have to ruff up the DF before you glue it. When all else fails, read the directions!: