Alternatives to Epoxy

[Bruce]

A sensitivity to Epoxy Glue is prompting me to search for alternative adhesives.

What glues are recommended?

Which non-Epoxy adhesives would work the best to create fillets on mid and high powered rockets?

 

[Bat-mite]

Is your sensitivity tactile or resperatory? If tactile, you should be wearing gloves anyway, no? If respiratory, perhaps a painter's mask?

I don't know much about glues, so I can't help there.

 

[Bruce]

Nitrile gloves and respirator help, but the only thing that completely solves the problem for me is to not use Epoxy.

 

[tsmith1315]

Are you also sensitive to polyester resin?

 

[Back_at_it]

Does not apply to fiberglass but for wood and cardboard tubes you are fine with regular old TBII wood glue. Just prep the mating surfaces by removing the smooth layer. Brush on a good layer of glue into both surfaces before attaching. Use a thin glue for fillets so that it soaks into the materials and you will be good.

I've built and flown G motor cardboard rockets and they hold together fine. The materials themselves will fail before the bond. I've had plywood fins ripped in half with the root still attached to the bodytube. Also had a fin rip a section of a LOC tube off. found the Fin in the field and it was completely intact with about a 4 inch long section of the tube attached.

For Fiberglass, I'm not sure what your option would be. Back in my days in the car world we use to use 3M 8116 panel bonding adhesive to build kit cars and body kits. That stuff would stay stuck even in car accidents. And whatever you do don't get it on you.

 

[mh9162013]

JB Weld

It might technically be an epoxy, but it's a lot different than the 5 minute, 30 minute and other clear-ish yellow highly exothermic epoxies I see used in model rocketry.

 

[Rob Campbell]

I second Tite-Bond II. Also, Tite-Bond III, Gorilla Wood Glue, or Elmer's Carpenters' Glue.

 

[DigBaddy]

I've made some nice fillets with Powergrab construction adhesive. Shrinks a lot, but seems to work well. Haven't used it for other structural things, but might be worth a shot.

 

[Bruce]

Are you also sensitive to polyester resin?

Have not tried polyester resin, but I suspect that since it has a strong odor, it may be problematic as well.

 

[rharshberger]

Have not tried polyester resin, but I suspect that since it has a strong odor, it may be problematic as well.

It has its issues as well, on thing is it kicks much quicker than the epoxies typically used in our hobby.

 

[Dotini]

A sensitivity to Epoxy Glue is prompting me to search for alternative adhesives.

What glues are recommended?

Which non-Epoxy adhesives would work the best to create fillets on mid and high powered rockets?

You might try original Gorilla Glue. It's possible to build up a very strong fillet. Minor bubbling may occur, but that can be filled if necessary.

 

[G_T]

I recommend not messing around with epoxy sensitivity. Don't use any anymore, and stay away from any that has been mixed in the last few days. It takes epoxy about a week to get to full cure. Even sanding it before then will trigger your reaction.

Consider using construction techniques that don't require epoxy. Perhaps this L3 project of mine will give you some ideas: https://www.rocketryforum.com/threads/sprite-6-and-a-baby-o.37382/ This sort of technique is more work, but quite suitable to BDRs such as one would fly in the east.

If you go to Black Rock, you can make rockets which are flying motor cases and have little to no adhesives in them.

Even the fabric layup where I vacuum bagged the fins in the thread I linked can be done with polymer finishes that don't contain epoxy. It isn't as strong, but it works.

Silicone rubber caulk could also be used to make fillets, just to add to your list. You won't be sanding it, and I don't know about painting it. But if you can find it, the old white Dow version that smells like vinegar when curing is tenacious stuff. Flexible, but sticks well to a lot of surfaces. Don't cure it near electronics or wire though. That odor it puts off is acetic acid and can corrode metal a bit.

You could also make fillets out of wood strips, like wood molding. Glue in place.

There are thickened versions of superglues you can use. Use kicker sparingly, as it weakens the glue.

Wood putty could be used to make fillets. When dry, you could saturate it with thin CA to harden it and improve the bond strength. It would still be a bit brittle though.

Gerald

 

[afadeev]

Consider using construction techniques that don't require epoxy. Perhaps this L3 project of mine will give you some ideas: https://www.rocketryforum.com/threads/sprite-6-and-a-baby-o.37382/ This sort of technique is more work, but quite suitable to BDRs such as one would fly in the east.

+1 on not risking your health for a hobby.
If I were you, I would refocus rocket-building efforts on kits that don't require epoxy, at all. That means no more Fiber Glass / CF kits. Fly the ones you have, but don't build any new ones.

Stick with building paper / balsa / plywood kits. There are plenty of choices and challenges among those in mid-power and high-power space.
TiteBond II works great on paper / wood products, and TB II glued LP/MP/HP kits are stronger than the materials that they hold together.
https://www.amazon.com/Titebond-500...652992786&sprefix=titebond+ii+,aps,138&sr=8-9
I like TB II so much, I bought a 1 gallon jug of it a few years ago. It's now down to about 2/3 ;-).

HTH,
a

 

[neil_w]

I like TB II so much, I bought a 1 gallon jug of it a few years ago. It's now down to about 2/3 ;-).

For what it's worth: the manufacturer rates its shelf life at 2 years. I've definitely used bottles longer than that, but if you're looking at stretching that jug to 10 years you should be aware.

 

[afadeev]

For what it's worth: the manufacturer rates its shelf life at 2 years. I've definitely used bottles longer than that, but if you're looking at stretching that jug to 10 years you should be aware.

Thanks for the heads up on TTL.
Confirmed here: http://www.titebond.com/product/glues/2ef3e95d-48d2-43bc-8e1b-217a38930fa2

My bottles don't even have a manufacturing date, so I have no idea how old they might be now, or how old they were when I bought them.
I'm planning to use them till they are empty.
;-)

 

[rocket_troy]

Another option might be UV cured resins. Yes, they limit your filler options and might need to be laid up in layers, but they can offer a strong bond when applied properly. Not at the top of the list of alternatives, but perhaps should be on the list somewhere. No idea how toxic they are? That could be a another showstopper.

TP

 

[bjphoenix]

I'm not sure if this is a real possibility but there are acrylic adhesives used in concrete construction as substitutes for epoxy.

 

[Jerry F.]

I have recently tried Gorilla glue, and more recently, TiteBond III...IMO, the TiteBond makes substantially better fillets on LPR/MPR's...Gorilla keeps leaving drop holes, but the TB III is smooth, and sets up very nicely...
Not sure how they compare for holding strength....

 

[ghostfather]

I've used the foaming wood glue based on polyurethane (in the States often sold as Gorilla glue) as the primary adhesive. The foaming type reacts with water in the air to foam a bit, and fill any gaps, and makes internal fillets automatically when attaching thru-the-wall fins. I wipe any extra glue away on the exterior, and make external fillets with another filled adhesive, usually epoxy filled with glass fibers, but a filled PU adhesive would work as well.
An advantage of polyurethane glues is that they bond with about anything, especially plastics where epoxy doesn't bond.

 

[danisman]

I'd also suggest judicious use of CA (cyanoacrylate or SuperGlue) where appropriate. For most paper tube and wood (especially balsa) joints, regular wood glue is excellent and works by soaking into the fibers of the two joined parts to create a bridging bond (which is why wood glue doesn't work on plastics and fiberglass). It's also a lot easier to work with (and safer).
CA works by "melting" the joined surfaces slightly and creates more of a chemical bond. CA comes in different thicknesses and these should be used for different purposes; the super thin CA (which cures the fastest) should be used with caution as it will run where you don't want it unless you take precautions to prevent. Also, some materials, like foams or extruded parts, will be melted by regular CA; an odorless formulation of CA can be used safely with these. There is a "de-bonder" product, although I've never used it and would advise learning to use CA properly so you don't have to resort to this.
Another common headache with CA is that the caps tend to get glued on to the bottle. This can be avoided by first wiping off the nozzle, then applying a thin layer of vaseline to the nozzle before re-capping. I always wear gloves when working with CA to avoid bonding my skin accidentally. Learning to use CA accelerator can also make gluing with CA more effective.
There's a good introductory video on types of CA and their uses here: https://www.apogeerockets.com/Advanced_Construction_videos/Rocketry_Video_357

 

[G_T]

Working on a project unrelated to rockets, I recently learned that many finishes will actually partially dissolve or destroy CA bonds.

Gerald

 

[danisman]

Any specifics on which finishes are incompatible with Ca? I’d love to know that! I haven’t found a problem with rattle can primers and paints (so far, at least)

 

[Grog6]

Acetone and toluene dissolve ca glue.
When I work with almost anything these days, especially urethanes, I use full tyvek dressout gear, with a respirator with organic cartriges on it. I saw a co-worker get that stuff on his arms, and within 3 days, he was broken out like poison ivy all over. I'd never seen anyone fully covered in calamine lotion before, lol.
I'm a firm believer in ppe.

 

[DES]

I've made some nice fillets with Powergrab construction adhesive. Shrinks a lot, but seems to work well. Haven't used it for other structural things, but might be worth a shot.

Yes, the Loctite Powergrab in the caulking gun tubes will make a nice fillet. I have not used it on a rocket, but I have used it to detail chamfers and fillets on concrete molds for countertops, up to as large as 3/4 inch radius. Put in as many fat beads as you think you need to fill the space, and drag it off with a spoon or dowel. Excess can be applied to the next fillet, and so on. It is thick, yet smooth, and does not run. Be advised, it will take a long time to dry completely when used thicker than say 1/4 inch radius, but it does work.

You want the white PVA acrylic version which is waterbased. Should not be an issue for epoxy allergy. Could possibly warp fins or cardboard tubes if used for large fillets. Don't use the solvent based polyurethane adhesive, unless you are doing flooring...

 

[JackC]

For fin cans, buy bolt-on aluminum fin cans from Max Q. For other parts, use set screws to bond pieces together (like a coupler tube inside an airframe). In places where you have to use adhesive, try construction adhesive you can purchase at Lowes or Home Depot. Hope you find a process that will work for you.

 

[Ez2cDave]

Have not tried polyester resin, but I suspect that since it has a strong odor, it may be problematic as well.

There is another possibility that has not been suggested here . . .

If you have any fellow rocketeers in your area, you might ask them to do the epoxy work for you.

Given your health concerns, I doubt they would turn you down.

Dave F.

 

[Sooner Boomer]

I tried making fillets using baking soda soaked in CA. I put down the soda in the fin joint and smoothed it out and shaped it with my finger. I then dripped thin CA onto the fillet. If you're careful, it works fairly well. You have to keep the tip of the glue bottle out of the soda powder.

 

[bjphoenix]

Yes, the Loctite Powergrab in the caulking gun tubes will make a nice fillet. I have not used it on a rocket, but I have used it to detail chamfers and fillets on concrete molds for countertops, up to as large as 3/4 inch radius. Put in as many fat beads as you think you need to fill the space, and drag it off with a spoon or dowel. Excess can be applied to the next fillet, and so on. It is thick, yet smooth, and does not run. Be advised, it will take a long time to dry completely when used thicker than say 1/4 inch radius, but it does work.

I had not thought about using this material but it sounds interesting. Fillets with 3/4" radius would theoretically be about 1/4" thick at the thickest part, so ballpark how many hours/days would it take for that to dry? Does it shrink when it dries? Does it dry as hard as epoxy so you can sand it? When I've removed things in my house that appeared to use "liquid nails" type adhesive the stuff was never completely hard.

 

[DigBaddy]

I had not thought about using this material but it sounds interesting. Fillets with 3/4" radius would theoretically be about 1/4" thick at the thickest part, so ballpark how many hours/days would it take for that to dry? Does it shrink when it dries? Does it dry as hard as epoxy so you can sand it? When I've removed things in my house that appeared to use "liquid nails" type adhesive the stuff was never completely hard.

Definitely takes a couple days to shrink all the way and is hard and sandable once it gets there. Shrinks less than wood glue, but still quite a bit, so more is needed when making fillets.

 

[G_T]

You could build up to that fillet radius in stages, waiting for previous layers to firm up but not cure so you still get a chemical bond. Perhaps score them to increase the mechanical bonding as well.

A thick layer of material that shrinks when cured can result in a stressed structure that is prone to fracture. Using successive thinner layers can help overcome this issue.

===

Petroleum distillates, mineral spirits, are now on my list when it comes to exposure weakening or dissolving CA. They were in combination in an oil-based finish I was applying (my concoction, actually), but the result was a removal of some (in some cases, all) of the CA and I think weakening of what was left. I had a structural failure during testing due to that. I didn't catch the problem in time. The finish, however, was excellent.

I have not done any rigorous testing, just hit the problem working on a stressed structure unrelated to rocketry.

Of course, acetone, probably MEK, Toluene, will also dissolve CA. Nitromethane is also a known solvent. Nitromethane + acetone is one version of a commercial superglue remover, at least in the past.

CA is not very chemically resistant! And unfortunately, many finishes contain solvents that attack CA.

Gerald