EBB's PHOTO GALLERY THREAD

[ebb]

BUY SYSTEM THREE T-88 STRUCTURAL EPOXY ADHESIVE AT YOUR PERIL.

To make these coaming corner posts each side required 3 pieces of 1 1/2" x 6" x 15" to be glued up into a single block of approx 4 1/2" X 6".
There are not many wood glues available for exposed exterior wood pieces. The only wood glue we can truly depend on is Resorcinol.
It is an formaldehyde powder/purple resin mix that is impervious to everything when bonded including water immersion and delamination. It needs careful measuring, controlled timing, controlled temperature, and extreme clamping to be successful. it leaves a prominent dark purple glue line. Not something desirable on a mahogany glue-up for the coaming posts at the cabin. So I thought!

Another is powdered urea-formaldehyde 'plastic resin' glue, mostly tan colored and activated by mixing with water.
It is water resistant, will not take immersion. But it leaves a lighter colored or no line at all and is often used for wood masts, spars and laminated tillers. It also requires pressure while curing. It is a little more forgiving with humidity and temperature. Generally these glues have trouble setting under 60 degrees ambient.

I would describe these glues as producing a chemical bond with the wood - while the next choice produces a mechanical bond. That is if it's not T-88.

The third choice is epoxy adhesive. My bloody choice. I have used Smith's 2-part Allwood and Tropical epoxy for years without failure. It says it will glue oily woods such as teak - and it does. T-88 makes the same claim. Laminates are put together with moderate pressure so that the glue does not all get squeezed out to starve the joint. Good epoxy is even more forgiving of humidity and ambient temperature. It's the only choice when the project temp is below 65degrees.

Structural epoxies are not laminating epoxies which are usually runny and engineered for fabric wet-out. Adhesive epoxies are stiffer, thicker, and smell mildly of toast and ammonia. Guess they are low VOC, nearly 100% solids, and are not waterbourne.
It was time to try a fresh system so I ordered SYSTEM THREE T-88 STRUCTURAL EPOXY ADHESIVE.
www.systemthree.com
It mixes just like Smiths Tropical Wood Epoxy: it is a viscous material that spreads easily because it kind of likes to hold together. Quite different than laminating epoxy which flows apart like pancake syrup. On the freshly milled mahogany there seemed to be quick wet-out . The glue was applied liberally with a toothed spatula to both sides of each joint. No holidays. The pieces were smooched together and squared up with clamps at right angle to the glue line and weight was put on top. Can't remember what weight but might have been tool boxes. The result IS a consistent 1/3mm glue line.....

DISASTER!!!


The coaming blocks have failed.

THE GLUE LINE IS PULLING APART
Barely noticeable across the top end grain the two glue lines are opening. So far only the wider top of the post is coming apart.

Have not yet pried at the joints. The wood may be moving because of hot weather and drying winds - the pieces have not spent time in the sun. The WOOD at the joints is not splitting -
just the GLUE is letting go!
The end grain of the wood is totally tight, not the slightest crack.
The whole point of this adhesive is to hold the wood pieces TOGETHER

NO MATTER WHAT.


DON'T BUY SYSTEM THREE T-88.
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You have to take my word on this one.
I've worked epoxies for decades.
Was extra careful with this project. Mah baby.
No solvents were used to prep the wood surfaces.
The mahogany has been covered and stickered dry and air dried for 30 plus years.
Honduras is not known as a problem wood to glue.
Freshly planed, milled, toothed for epoxy to grip.
The pieces were sequentially stacked as cut.
The two-part T-88 carefully measured, carefully mixed.
The method used is to turn the two parts together on a square of acrylic sheet with a two inch spatula/knife. Excellent and thorough.
The glue was not mixed in a cup.

After mixing it was allowed to rest for 1/2 hour.
Then applied to room temperature mahogany.
and the pieces smooched together wet on wet.
What did I miss?

As far as I'm concerned this is a failure of

S Y S T E M T H R E E .
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Good Cod, and I just got started using their waterbourne LPU in the cabin.
And I thought also for the coach roof outside.... maybe it's garbage too?.....

[ebb]

T-88 is probably a good enough glue.
It is that too much was asked of it.
There just isn't enough glue to wood mass.
Guess it would work better if multiple layers of mahogany were laminated together - say 1/2" thick planks in a stack.
More glue area might minimize or almost stop the wood's ability to move.
Could say that this epoxy has limits as a wood adhesive.

There is also the possibility that too much of the wet of the glue was absorbed into the dry wood. Don't know if this can happen with this kind of glue. Penetrating surfaces would be a plus and increase the bond. No? Providing more tooth by scouring the surfaces on mating pieces might have created too much more surface area for the adhesive.

In gluing large pieces - much like biscuits or dowels are used in panel and table top edge gluing - I could have worked in three or four splines along each glue face by cutting matching 1/4" grooves and adding 1/4" splines that would have increased the glue area and maybe helped to stabilize the large pieces I felt I had to use.
The splines would have to be vertical grained. If the grain of the spline is the same as the work then the relatively thin strips might split. I would have to make up bread-slice pieces with short grain 90 degrees to the work.
An easier substitute are 1/4" 5ply Meranti Aquaply strips. 1/4" Meranti made overseas is often slightly thinner 6mm, thereby giving epoxy some groovin room.

Major pieces that these corner posts are will require they be made over again. BUMMER. I would redo them as described. (See later post.)

As a last harrah, mechanical fastenings could be tried to pin the damned post together. But I know the wood will win and delaminate in Tahiti.

Yet one more desperate idea:
Numerous holes could be drilled into the three pieces from the inside face and a bunch of mahogany dowel pins glued in.*
It's a chancey proposition because the main glue-up now has to be considered a secondary and failing fastening - and the dowel-pin quick fix the primary.
So we'll have to think this through. Wood dowels look good at the moment because the all important lags - that will hold the corners to the cabin - are going to go thru some of them.
(I'm going to try this method.)

A good dunking in penetrating epoxy. (for ME - this sucker is falling apart!)
And 20 coats of varnish.

Have tossed the T-88 because the stuff can't be trusted..... garbage.

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* found honduras m. dowels on the net at Constantine's Wood Center. If they fit tight in the drilled holes I'll use the tan glue and have a saw cut relief the length of each dowel pin so they can be driven in wet all the way.
Constantines has been in business for more than 200 years. How bout that!
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What gets me is that I might have missed an important step - using a new product.
However T-88 is a recognizable adhesive type that I've worked with for decades from one manufacturer in particular, but a few others as well.
What really gets me is that this failure trivializes the effort. It could have been something structurally more important - like a spar, bowsprit, boomkin, window or hatch - that could fall apart at a bad time - without warning.
If the proportion of wood mass to glue area was too much - and the glue-up began moving - then at least the adhesive should have pulled wood off the glued faces. Only the glue is cracking as the wood is moving (the tiniest bit).

[ebb]

Mike, who runs the estate shop here, recalls that in some System Three literature there is a suggestion that prior to using T-88 Adhesive a System Three penetrating epoxy should be used to prime the wood to be glued.
This not correct.

For all intents the failure of the glue actually has the look of a starved joint.
Even though we have a requisite glue line.

A Technical Data Sheet for T-88 states:
(no mention of wood moisture content)
"Glue line thickness is not critical and clamping is not necessary...
"Oak is a highly porous wood with a strong tendency to absorb resin and yield starved joints of substandard strength. Preferred practice is to apply a liberal coat to both surfaces and without mating allow the parts to stand open for 30-45 minutes. Dull spots indicate complete absorption and should be touched up... then assembled and clamped with minimal pressure - just enough to ensure contact. Or the oak can be presealed with a thin coat on both mating surfaces and cured separately, then sand lightly, apply fresh T-88 and join lightly."
Teak surfaces require vigourous wiping with lacquer thinner and while still moist dried with rag. Repeat if the surfaces don't have a whitish color "indicating the extraction of surface oil."
My ancient dry honduras mahogany could be considered porous, I suppose.
I did not do the 1/2 hour open time to see if absorption was happening. However, there arguably was plenty of glue applied to both surfaces and a mild pressure was continuously applied while hardening that might have closed nano gaps caused by liquid being absorped by the wood. The block when dry had an even glue line all round. This indicates no glueless areas caused by absorption. Wrong.
The problem starts to be noticed at the large endgrain area (the top of the post) and there are indications (from the cutoff wedge pieces used outside to prop the mast) that the wood pulls away evenly all along the glueline.

Smith & Co.'s Tropical Hardwood Epoxy (Jamestown) requires NO PRETREATMENT to stick any kind of wood together permanently. From Lignum Vitae to Teak to Mahogany.
You have to know something about the glue. End-grain gluing is ALWAYS a problem with any glue. This is not end grain gluing but matched flat to flat grain. But Smith's doesn't need a crutch.

Now, to be absolutely sure we would need a fair comparison in a second post glued up with Smith's Tropical.



SO NOW, LET'S OPEN UP THE JOINT:
I forced a chunk of the laminate apart on one of the cut-offs with a stiff-blade putty knife.. These are the large 'waste' pieces now disintegrating full time in the sun. The wood has 100% pulled away from the joint line. Yet the glue did not want to let go right away.
....Inside the mating surfaces show visually and by feel that the adhesive was evenly distributed on both surfaces. But one surface shows the layer of glue - the mating surface shows no sign of adhesion!
The only conclusion is that the glue was widely absorbed on one side leaving few areas of connection.
The glue line turns out is essentially a figment.
Even though there is a apparent visual line of glue
one side or the other side seems to have let go!
There is no solid connection of wood to glue to wood except one small area WHERE THE WOOD RIPPED OFF FROM THE MATING SIDE. Quite odd.
This could be a lack of experience with both materials on my part. We've had a hot summer here and the wood is very dry and has very low moisture content. I didn't put a meter on it.
Taking the 15X loupe (Lee Valley) to the glue lines shows some lines 'sticking' intermittently to one or other side. While other lines have separated a complete length from one side.
I remember when the T-88 was mixed it didn't feel like the thick body of Smith's epoxy I'm used to.

I don't believe the Smith's Tropical epoxy could have just disappeared like the T-88 did.
Why one identical mating surface accepting glue and not the other?
Why one surface appearing not absorbed (evident layer of glue) and the opposite surface starved? Insane. These are identical sequential pieces.
Because of the weirdness of T-88, my goof or not, I'm sticking to the other product I know and trust. I'm positive I could never force a Smith's joint apart with a PUTTY KNIFE.
Smith's CPES, a penetrating sealer, is not a recommended surface pre-treatment for Tropical Wood Epoxy.
To be absolutely fair, the pieces could be primed with thin epoxy and allowed to set. Then the block would be sanded and assembled and glued with structural epoxy. THis is probably the way I should have done them.
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THE FIX IS IN.
Mike suggests that with a wide thin resaw blade on the Laguna bandsaw we could easily cut along the glueline - ERASE THE JUNK ENTIRELY and then stick the block back together with another glue that has balls.
Minimal dimensional change.
Some cross dowels will be needed to key the blocks from sliding when gluing. I'll drill those in before separating the blocks. Next time: RESORCINOL.
Plastic Resin (urea-formaldehyde) will not survive soaking or swell/shrink heat/cold cycles of the coaming post environment. Epoxy has an elevated temp inadequacies and similar problem with high moisture or wet that coaming posts are subject to. Resorcinol is the ONLY glue for the job. R. is the ONLY glue that survives BOILING tests.
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Type into your search engine APPENDIX C SUPERIOR ADHESIVES FOR THE MILLENIUM. This is Larry Pardey's condemnation of epoxy and its major purveyor's. It's a great article, from a book whose title escapes me. A professional woodworker's perspective. Epoxy has its place in layup, but never as a wood glue. The tropics will destroy epoxy in a couple seasons. Really can't use it in any exterior wood glue up. Guess I got lucky!

[frank durant]

Ebb....I just spent about an hour going through your pics. Hope to steal a few ideas from you.As I looked at the date of the last ones I realized..we need an update More pics please

[Tim D.]

I drove by Little gull last Sunday, and if I had my camera I would taken some pics, because I have been thinking the same thing.

[frank durant]

Back on page 11, Bill showed us Ebb's "engineering table". Wonder if the lack of updates indicates too much time at the table and not enough on lil gull ? ;-) Only teasing Ebb....you are creating a masterpeace...extremely well thought out and engineered. Now...about those updates ........

[ebb]

As I walked by something caught my eye and I stopped.

A crane fly was caught in a spider's web
It furiously tried to get untangled, beating its wings, bouncing rhythmically in air.
Each time the spider approached the fly became more frantic making the spider back off a little.
The crane fly was more than twice the size of its captor.
It seemed to be tiring. The bouncing stopped.
The fly quietly and deliberately used a free leg to strip an invisible sticky thread from a fouled leg as the spider came closer and closer.
Just as the spider was ready to pounce the leg came free!

But the fly was still caught, it helicoptered its wings again and broke away,
landing close by, seeming to shiver.
The spider remained suspended and still poised to wrap up the catch of a lifetime.

Watching the drama, I thought about helping the flier get loose from the trapper.
Wondered if that would change the course of the universe.

I was sure the fly wasn't going to make it.

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Making some progress inside.
Photo soon?