On Tue, 15 Nov 2005 01:46:14 -0800, Owen Lowe
wrote:
(My spastic ISP does the same thing to me, picking and choosing among
msgs, so I'm hoping if I give this a new header it'll get through.)
Hi Owen,
Let me address a couple of these issues. I don't aim to "convert"
you, but I've had great success with poly glues over the years and if
they are used within their parameters they are really effective.
I don't care for the polyurethane glues - like Gorilla Glue. The foaming
action will force the joint apart unless it's clamped
Absolutely true, which is why you have to be alert when you are gluing
pens together with it. But to be fair, what glue _don't_ you have to
clamp? The foaming action is one of the benefits of the glue, rather
than a liability. It is _supposed_ to foam to fill gaps and better
penetrate the surface of the two things being bonded.
-- and even then,
the foam will squeeze itself out as it cures and expands.
The glue will only foam out of a joint that is too loose or if you use
too much of it, but even then, is easily scraped off. Granted, it's a
bit messy, but the bond is worth it. And any glue will squeeze out of
a joint when you put them together. It's only a matter of when you
have to clean it off.
If the joint
is overly loose in the slightest, the poly glues aren't strong because
the foam which fills the gap has very little strength.
Sorry, that is absolutely untrue. I have used two different brands of
poly glue to make wooden barrettes. I attached the metal barrette
backs to the wood by simply pushing it into a puddle of the poly glue.
Ten years later, after exposure to alcohol- and who-knows-what-based
hair products, and hundreds of openings and closings, being flexed and
bent around my wife's mass of curly, Italian hair, the bonds are just
as strong as ever. The epoxy bonds I tried early on, however, have
cracked and some have failed.
The glue didn't foam up a la "The Blob" but rather just foamed
modestly at the surface. The amount that poly glues foam is directly
related to the amount of moisture present, both in the wood and in the
atmosphere.
Additionally, the barretes were often made of woods I laminated
together with poly glue and the finished thickness is no more than
1/8" on them, which means there is a 3" long bond that is only 1/8"
thick holding these two or more pieces of wood together.
Further, I have made turnings with mortise and tenon joints that were
somewhat less than "tight," shall we say. Joining those two pieces
together with anything other than a poly glue would have been iffy, at
best, because the tenon didn't bottom out in the mortise. However,
with the poly glue, as long as the side bond is fairly snug, the empty
space in the bottom will be filled with the foamed glue and will
absolutely provide some bond...certainly more bond than any brand of
white/yellow glue would have, and definitely more flexible than an
epoxy.
I'd much rather
use an epoxy; they do a fine job filling gaps and stay relatively
flexible to maintain the bond as the wood expands and contracts.
Well, we are talking about wood to metal, too, and "relatively
flexible" isn't always the ticket.. There can often be visible
movement in wood with changes in humidity, which doesn't effect metal
in the slightest. Further, poly glues are proven to provide an
excellent bond on oily exotic woods, without any prior surface
preparation. Is that true of epoxy? Don't you have to wipe it down
with acetone first?
I'm not saying epoxy is inferior, or that poly glue is superior in
all applications, but you don't have to mix poly glues, either. And
in order to get the gap filled, you have to overfill the joint,
squeezing out the excess and still have to clean up dribbles. No
better than the poly glue in that regard.
Epoxies come in all sorts of flavors with regard to curing time, though
they are all 2-step as far as I know. One can even mix in all sorts of
colorants to custom match a wood.
I don't know if you can color the poly glues or not, but the point is
to not see the glue anyhow. Polyurethane glue is made to bond, not to
be seen.
For my turning projects, I usually use
a 5-minute formula so I can mix, spread, assemble and set aside for
15-30 minutes.
Since I _have_ had bad experiences with epoxy bonds cracking and
failing, I would rather wait the couple of hours that are required to
get a decent bond with the poly and be sure of my bond. Again, that
is from my _personal_ experience with both of the products.
And I don't use poly for all gluing jobs. I also use CA glues, yellow
wood glues (Titebond II) and epoxies on occasion. But whenever I know
a piece is going to be under extreme stress, under water or exposed to
harsh conditions or things like detergents or alcohol, or I'm bonding
oily exotics or if I am bonding unlike materials, like metal-to-wood,
I always reach for the Gorilla Glue.
I'm not a salesman nor do I own stock in any of the poly glues, but I
do like to let people know about the effectiveness of a product that I
have had good experiences with. As with any new(er) product, there is
always a lot of misinformation floating around with regards to it (I
remember hearing, back in the mid-'60s, that the M-16 rifle could fire
one of its .223 slugs completely through a car, including the engine
block, bumper-to-bumper!!). I certainly don't hold my experiences up
as the final word on this or any other adhesive. I just want to set
the record straight as someone who has used and experimented with this
glue for at least 10 years.
--
Chuck *#:^)
chaz3913(AT)yahoo(DOT)com
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September 11, 2001 - Never Forget
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