Resorcinol Resin

Larry Lowenkron

Larry Lowenkron

Member
I retired from a "glue" factory that made resorcinol resin. It was without a doubt our top of the line product...(most expensive too!) If you have doubts regarding it's strength, just look at lam beams used in construction! On the other hand, I am just amazed that Urea Formaldehyde resin was approved for civilian aircraft use. (have you ever noticed what happens to particle board left in a wet environment?)
The DH Mosquito used UF resin, but then they were not expected to have that long a life time. Even so, some of them that were used in SE Asia were know to have actually delaminated in places (without the help of battle damage).
T-18 is also a wonderful aircraft glue, however there is some question on whether or not it is a "legal" aircraft glue. They tell me it is, so who am I to doubt them!
BTW, the hardener used in Resorcinol Resin is Paraformaldehyde. I would advise that if you use this resin, you take proper precautions and use the correct personnel protective equipment as the mfg recommends!
 
> I am just amazed that Urea Formaldehyde resin was approved > for civilian aircraft use.

Pardon my rather juvenile sense of humor, Larry, but that sounds to me like someone got confused or drunk, stumbled to a tank of Formaldehyde and took a piss in it. :roll:

Jonathan
 
Well, I see that I really need to proof what I write. I meant T-88, not T-18.
Weldwood makes both a UF and an RF resin.
Yes Jonathan you are on the right track, but they would really have to work hard to get the correct mole ratio, and would probably pass out in the process. Also requires heat to set it up, or you have to wait a while for it to set up. See Wikopedia for a really good explantaion.
 
There's a pretty good discription in AC43-13-1B para 1-4.

The problem is that since we have certified aircraft, you usually have to get you IA's approval of what you are going to use.

I think that RF is the only "approved" resin for wood repairs.
 
I believe you are right. I just wondered what your opinions about the two types of glues are.

Now, if I could just remember who I loaned my AC43-13-1B and other aircraft tech books to...
 
Other than T-88, I haven't really used any other a/c glues. I did like the T-88, and I know that Steve Wolf uses it on some of the planes he builds...He built the GB racer replica, and the wings for the Hughes H1 replica, etc. I need to go back thru my old data from work, and see what I can find. It's been a while!
 
If you will get out the latest AC-43..........it will say that any epoxy glue that meets ASTM or SAE requirements is approved.
 
My copy of AC 43.13-1B CHG 1 says that epoxy must meet the approvals of a Mil Spec, Aerospace Material Specification or TSO for wooden aircraft structures and are "...compatible with existing structural materials in the aircraft and the fabrication methods...". You still end up getting your IA to sign off major repairs, and he (or she) has to make the call if it is approved. We have FAA ghost stories here about them not approving a Viking wing repair where they used T-88. Steve Wolf rebuilds Shaun Tuckers wings every year, and they have NEVER had a glue failure using T-88. Sometimes you just can't help but wonder who is protecting who from what!
My point is, that 43.13-1B is still kind of nebulous, and you still have to noodle your way through the approval process in certified aircraft.
 
By the way,

The FAA has a list of their online Mechanic Advisory Circulars, including 43.13-1 and -2
at http://www.faa.gov/mechanics/regs_policy/search/
 
I don't think AC-43 is nebulous. Call Mike Grimes about the verbage. 661-948-1087. He co-wrote that part on glues. By the way, I have a letter from Chem-Tech, who makes T-88, stating that their glue meets the basic spec stated in AC-43. Mike is a fan of West System, which also meets the spec. I have built up about ten pairs of wings, including six pairs of Bellanca wings using T-88. Never a problem with paperwork or serviceability. If your IA won't deal with epoxy, maybe he likes casein glue.........find another IA!
 
I used T-88 and West System Epoxy on the crate both excellent products! Lynn N9818B the wings continue :)
 
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