new adhesives

Do not dismiss Gorilla glue - it is incredibly strong and waterproof but needs clamping tightly for hours (well at least one!). It fills gaps nicely - I use it quite a lot.

This structure is for a Watt's Beam Engine (Steam) that I have under construction. It has been pinned in places to speed up construction (I don't have much patience waiting for glues to dry!)

pkrankow wrote:..........The foaming action makes a horrid mess and the bond relies on large surface areas for strength so it is near impossible to build with...............
Phil

My preference among the Poly-U glues is Elmer's Probond. I use it for laminating plywood, skinning foam wings with sheet balsa and for building foamys.

Foaming usually results from too much glue and/or too much moisture being applied. I never wipe down the parts with a damp towel, but use a mister with a drop or two of dish washing liquid added. The detergent reduces the surface tension of the water and it will sheet rather than bead. These poly-u's don't require much moisture to set up, although the set time will be longer if the parts are only slightly damp. When gluing parts, I don't spray them directly, but spray the mister into the air and wave the parts thru the mist --- that's all the water needed.

I did a little experiment some time back to see how well pro-bond would work sheeting a foam core. I applied the adhesive to the balsa and used a squeegee to spread it very thinly -- just enough to change the color of the sheeting. I then used the air spray method to dampen the core, applied the sheeting and weighted it down. Bags of lead shot work really well for weights. After a 48 hour set, I tried prying the sheet away --- either the foam came out in chunks or the balsa splintered. I took another section and melted the foam away with acetone --- the balsa sheet looked like it was covered with lichen. The Pro-bond had expanded to fill the gaps between the beads by a 1/16" or more and remained firmly attached to the balsa.

You do need to apply pressure, so some types of construction just will not work. I have had good luck with the poly-urethanes, but in specific applications and using specific techniques. My experience has been that it produces a bond as good or better than other adhesives when used carefully and the substrate breaks away before the glue joint.

andrew

[quote="ian1954"]Do not dismiss Gorilla glue - it is incredibly strong and waterproof but needs clamping tightly for hours (well at least one!). It fills gaps nicely - I use it quite a lot.
quote]

Ditto
I wouldn't use anything else on the hinges of my biggies.

yep, i've got to the point i call 'Gorilla' glue or urethane glue 'lazy guys epoxy' cause its about as strong and i don't have to mix anything, us smaller amounts to reduce foaming.

I did some surfin' on the Elmers Probond Advanced and apparently its pretty good stuff, might even be better then the 'gorilla' stuff, longer shelf life and very little or no foaming.

The Loctite Go2 glue was mentioned in r/c groups as good stuff as well.

I find Gorilla glue to be very helpful in my foamie wings. I converted many of my profiles to foam wings and this type of glue has been a terrific contribution. In combat, the carnage is unavoidable and once again this stuff is like liquid foam. When parts ore missing or you don't want to have the foaming ooze, I place clear packing tape over the hole or the repair. Ken

lol, i repaired a cheep oscillating sprinkler i use sometimes, using packing tape and 'gorilla' filled in the missing plastic, worked great!

Maybe I don't know how to use Gorilla glue.

I know that the only time I have had excellent results are in structure repair on dimensional lumber for sistering joists and rafters, as well as removing squeaks from subfloors by injecting a line of Gorilla glue along where the subfloor meets the joist. It also weather seals shim gaps like nobody's business!

When I have made glue-ups that get sawn the glue joint fails as the board is cut. When I scrape off excess glue the now-exposed joint becomes excessively weak, in fact the above mentioned subflooring can be lifted without super-human effort after scrapping the excess out of the joint. The glue is quite strong until the excess is scraped!

My efforts with stick building have been disasters in expansion. Any structure that is going to have finish sanding, sawing, or carving done I have used other adhesives since Gorilla glue is compromised (in my experience) by having the skin removed from it.

My other experiences with Gorilla glue and modeling have been an uncontrolled foamy mess as tiny amounts of glue expand into large messes requiring hours of effort to clean up leaving weak joints behind.

I would rather use from the plethora of readily available adhesives what I have had excellent experiences with than try p-u glues again.

White school glue works quite well, other than the dry time and lack of moisture resistance. PVA wood glues such as Elmer's also work excellent, with the same dry time problem as white glue, but resistance to moisture. CA is painfully stinky, but quick and strong. Celluloids such as Testor's and Ambroid are a treat to work with, except the smell. Epoxies are readily available and can be speed-matched to the project, and accept many different fillers. Many can be cleaned and sanded to accept paint.

I am open to trying different products. I have used regular Gorilla glue, and Low Foam white Gorilla glue. I may consider other polyurethane products in the future.

I also do not work with foam airplanes currently.

Phil

Hey, Phil ---

When poly-urethane foams up, the foam has very little strength at all --- it cuts easily and can be mashed flat with a thumbnail. The trick for me is to use very little glue and minimal moisture --- both can cause excess foaming, push the joint apart and leave a weak honeycombed glue line. Clamping is imperative. The PU's don't bridge well because of the honeycomb nature of the bridge, so the joint must remain tight. If you get a thin, non-foaming adhesive line, these products can be super strong.

andrew