Hatz Biplane Association

That resorcinol glue is hard to beat---built a plywood airboat 40 years ago, it held together long after I abandoned it to the back lot. Gotta keep it warm though, or it won't cure--(directions on can)---most of the props over 10 years or so are glued up with
resorcinol--can't miss that purple stain between layers...It was one of the few FAA approved glues for wood construction for
a long time. Built boat when ambient temps were 40~50°F---had a lot of time to fit up & glue, then turned on the heat &
left it on overnight to cure.. Checked a test sample next morn & hard as a rock.

I used T88 and have had no problems with centersection bow or wing tip bows. I woud think that it's 6 of one and half a dozen of the other. One glue will get the same results as the other, just the mixing and/or cost may differ.

I used T88, applied on both sides and clamped. I did have to prepare and make a trial run first. I was concerned about the same things as you are. I had enough time to spread glue on both sides of all 5 laminates and get them clamped. The bond came out perfect and there has been no separation but it has only been a short time.





My build progress can be found here:
http://www.edwinwhite.com/hatz.html

In the past I have used T-88 exclusively for airplane wood glueing. I am preparing to glue up the curved piece on the trailing edge of the Wing Center Section. I have preformed the strips and am ready to glue. My thought is that T-88 is not that ideal in some ways for such a large glue surface area. For one thing, that's a lot of mixing the sticky stuff. Mostly, though the heavy consistency of T-88 makes it not flow and spread that well. If you coat one surface with T-88 then put the two surfaces together, work them around, then pull them apart, one surface will still have large areas with no glue on it. You can of course add glue to those areas but even after putting back together and pulling apart there are areas that don't "string up" when pulling apart, indicating the adhesion between the two surfaces is maybe not so great in that area. This can be aided by working the parts around against each other more and clamping, but that's a lot of working and clamping on a laminated bow structure. Plus the T-88 starts getting noticeably firmer in 20 minutes, which I suspect it will take at least that long to get all that glue spread around and all clamped up in the jig.

I have gotten two other glues to try from Wicks. One is Weldwood and the other is Resorcinol. The weldwood powder mixes with water to make dark brown heavy, gooey paste which has about the same ability to get "total bond area" as the T-88 mentioned above. Furthermore its instructions call for significant clamping pressure, whereas the T-88 instructs that clamping pressure is not required so long as the joint is not "molested" during the curing period.

The Resorcinol is a purple syrup that mixes with powder to make a runny purply viscous liquid. If this glue is placed on one surface and the surfaces placed together when pulled apart (without really any of the sticky stringy effect you get when pulling apart the T-88 because it is not very gooey) there is total coverage on both surfaces even if the original application to one surface was fairly haphazard. I'm not sure what clamping requirements go with the Resorcinol. The working time of Resorcinol is listed like 3 or 4 hours.

My tendency is to use the Resorcinol because its easy to mix, easy to spread and easy to get total surface area coverage. It was suggested to me to use an epoxy glue for this lamination. I'm thinking the Resorcinol qualifies as an epoxy since its 2 parts, but, really,............. is it???

Bottom line: Does anyone have any experience (especially bad ones) with separation of these laminated structures and what glue did or did not work??

Thanks for any input.