# Recommended Epoxy for beginner?

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#### Bluegillbronco2

##### Well-Known Member
I just recently was gifted the Madcow 2.6 inch Honest John for my level 1 cert kit. It will be my very first build with fiberglass. I was wondering what sort of epoxy anyone recommends. The instructions say to use 5 minute epoxy, but I wondering if there were any spesific brands/types that are better.

And also how would you recomend painting fiberglass? I got a can of Rustoleum "Army Green" specifically for this kit, do I need to prime or sand the fiberglass? It seems pretty smooth out of the package but I was wondering if the paint would have a hard time sticking.

#### cerving

##### Owner, Eggtimer Rocketry
TRF Supporter
Don't use 5 minute epoxy on fiberglass, it doesn't hold up very well under stress. I use RocketPoxy, but a lot of other guys use West Systems or Aeropoxy. They're all very strong if you follow the directions carefully. They key thing is that you need to roughen up the fiberglass areas that are going to be bonded, I use #60 sandpaper. Get it good and rough, you'd be surprised how hard you actually have to sand fiberglass to put decent scratches into it. Afterwards, wash off the dust and wipe it down with 91% isopropyl acohol to clean it.

#### djs

##### Well-Known Member
If you're just getting started, Rocketpoxy is a good choice because it's not super expensive, and easy to mix (1:1 ratio). Have fun building (and flying)!

#### Rex R

##### LV2
I have used; hobby shop (re branded usually 'Great plains'), but have switched to 'Devcon' 2 ton epoxy since I can buy it locally w/o driving 40 miles and I am more likely to get the type I want(I have bought what was labeled as 20 minute epoxy only to find it was maybe 6 minute variety(BSI-hobby shop)). as for painting it depends on, the color of the fg and how transparent the paint is. if the tubes are black and the paint is a light color...then a gray primer would not be amiss. generally some sanding is required say, 220 grit followed by 320 grit(60 - 80 grit where you want the epoxy to stick).
Rex

#### Nytrunner

##### Pop lugs, not drugs
TRF Supporter
I like 5 minute epoxy for lo-speed paper/plywood mid/high-power (Loctite Heavy Duty ftw).
If the instructions call out 5 minute, its probably safe, but Don't try and go supersonic on it.

When I build something for speed or L2, I'm planning to use Rocket-poxy for the fins and an undecided system for structures.

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#### MikeyDSlagle

##### Well-Known Member
About the cheapest stuff I've found is US Composites. I use their 105 thick stuff iith medium 3:1 hardener regularly. It's what I started with and isn't difficult to use. I also have their 635 which is a thinner "laminating" epoxy, but haven't used it yet.

https://www.uscomposites.com/epoxy.html

They also have an epoxy glue, Fasco 110, which I think is comparable to Rocketpoxy, but not positive.
They also sell fillers, cloth, pigment and measuring/mixing supplies. A good place to start.
I suggest also getting a small scale to measure your epoxy. I use a pocket scale from Harbor Freight. Less waste when mixing small amounts.

Mikey D

#### DavidMcCann

##### Well-Known Member
Rocketpoxy will be the best quality/value/availability.

I also like aeropoxy es6209

Rocket poxy x 3

#### mpitfield

##### Moderator
Staff member
Global Mod
Rocketpoxy will be the best quality/value/availability.

I also like aeropoxy es6209
X2, but if you are on a budget the ES6209 is not for you.

RocketPoxy

#### Todderbert

##### Well-Known Member
About the cheapest stuff I've found is US Composites. I use their 105 thick stuff iith medium 3:1 hardener regularly. It's what I started with and isn't difficult to use. I also have their 635 which is a thinner "laminating" epoxy, but haven't used it yet.

https://www.uscomposites.com/epoxy.html

They also have an epoxy glue, Fasco 110, which I think is comparable to Rocketpoxy, but not positive.
They also sell fillers, cloth, pigment and measuring/mixing supplies. A good place to start.
I suggest also getting a small scale to measure your epoxy. I use a pocket scale from Harbor Freight. Less waste when mixing small amounts.

Mikey D
You mentioned 105, did you mean 150? The 105 is by West Systems at the bottom of the page.

#### blackbrandt

I use the US Composites 635 Medium 3:1 and mix it with colloidal silica for bonding. Never had any problems. And it's super cheap, at $40 for a half gallon. #### Buckeye ##### Well-Known Member TRF Supporter I think the hobby shop "Bob Smith" epoxy works fine. I use the 15 min, 30 min, and 3 hr! The squeeze bottles are easy to use and very good at metering out small quantities with little waste. Plus, the shelf life of the stuff is many, many years. #### MikeyDSlagle ##### Well-Known Member You mentioned 105, did you mean 150? The 105 is by West Systems at the bottom of the page. Doh! Yes that is what I meant. The 150. Sorry for the misdirection. Thanks. I've never used West Systems. I know at least the 16 oz and 1 quart size kits (the two smallest) come in squeeze bottles. They also sell squeeze bottles so if you order a larger kit, grab some bottles. For starting out, US Composites is a great one stop shop. They sell chopped fiber, fumed silica and micro balloons too. A good cheap source for learning how to mix fillers. Great customer service too. Mikey D #### rharshberger ##### Well-Known Member Doh! Yes that is what I meant. The 150. Sorry for the misdirection. Thanks. I've never used West Systems. I know at least the 16 oz and 1 quart size kits (the two smallest) come in squeeze bottles. They also sell squeeze bottles so if you order a larger kit, grab some bottles. For starting out, US Composites is a great one stop shop. They sell chopped fiber, fumed silica and micro balloons too. A good cheap source for learning how to mix fillers. Great customer service too. Mikey D +1 the US Composites 635 3:1 and the 150 3:1, excellent bang for the buck, easy to use at temps above 60°F no heat needed for proper cures, and suitable for most builds including some high performance builds. #### AfterBurners ##### Well-Known Member BSI 15 minute #### Steve Shannon ##### Well-Known Member TRF Supporter #### dr wogz ##### Fly caster I used the Bob Smith stuff on my WM V2 (2.6") and wasn't happy with it. (great for paper, balsa and ply; R/C airplanes & such..) I did rough it up, but maybe not enough. I've since switch to West systems, and much prefer it. But, sadly, they don't come in anything smaller. A friend & I share the cost, and the epoxy! I also like the West 405 low density filler for fillets & fairings.. sands & shapes easy.. No One has mentioned the Hysol line from Henkel / Loc-tite. Some of their epoxies should also be up to the task. I've been tempted, but I've only used them at a former job for ceramics to stainless steel applications. #### davdue ##### Well-Known Member TRF Supporter Definitely don't use the 5 minute stuff. My son has that same rocket that he used for his Level 1 Tripoli cert. We built it at the rocket pasture one day and he flew it the next. On subsequent flights we have had to re-glue fins that popped loose a couple times. I would use West systems with Coliodal Silica but that is because I have always used that for all my high power builds. I haven't used anything else yet. I one a set of Aeropoxy as a door prize but have yet to use it. I understand it is a lot thicker than West Systems. #### Bat-mite ##### Rocketeer in MD I used Bob Smith 30-minute on my FG Rocketry Warehouse X-Celerator. It held up fine for several flights (then I lost it). You can walk into Hobby Lobby and buy it for$11. And yes, I have graduated to RocketPoxy and I love it; but for a first time, Bob Smith is pretty danged easy.

Don't use 5-minute. I guess you could call MadCow and get their take on it, but I believe that 5-minute epoxy cures too brittle. Epoxy needs to have some give (it's very subtle, but it's there). Also, with 5-minute, you have to be really quick, and first-time builders usually aren't.

The biggest differences between using (note the word "using") BSI and RocketPoxy is in the consistency and cure time. BSI is very runny. You have to plan ahead and be very careful. But this can also be to your advantage when doing internal fillets, if you need to drip the epoxy along the joint, and let gravity work for you. BSI is also clear, and can be hard to see. And they don't make any dyes for it, that I know of.

RocketPoxy is more creamy in consistency. And the cure time is something like two hours, so you can afford to make mistakes and clean them up. A lot less runny, and if you mix it and let it wait 20 minutes or so, you can smooth it on like peanut butter. Also, it usually comes with black dye, but you can purchase other colors, too.

Another note: I have not looked at your kit, but I assume it has TTW fins. Some people like to use JB Weld epoxy on their fin roots. JB Weld is designed for car engines, and can take a lot of heat. It has steel in it. So a lot of people us it for the fin root at the MMT. Also for retainers, which can get really hot. Something to consider. Available at car parts stores and Home Depot, probably Wal-Mart, too. But it is more expensive by volume.

#### jrkennedy2

##### Well-Known Member
In addition to the epoxy, you might want to use nitrile gloves, 3mm or 5mm would be good. I've heard that if you develop an allergy to the epoxy/hardener, it is miserable to work with epoxy from then on. I'm not sensitive to epoxy but I have started to get that way with CA adhesives. Sorta sux if I happen to be using a lot, I start to wheeze a bit....

Just a thought...

#### DavidMcCann

##### Well-Known Member
Another note: I have not looked at your kit, but I assume it has TTW fins. Some people like to use JB Weld epoxy on their fin roots. JB Weld is designed for car engines, and can take a lot of heat. It has steel in it. So a lot of people us it for the fin root at the MMT. Also for retainers, which can get really hot. Something to consider. Available at car parts stores and Home Depot, probably Wal-Mart, too. But it is more expensive by volume.
Consider the resistance of the items being joined, before going through the trouble of using a high-temp epoxy. I've never scorched a paper MMT....so why worry about the joint on a glass tube? I use JB on retainers, but realize it's likely overkill and I've got a couple put on with 5 minute epoxy and haven't cracked one off yet.

I built my L1 rocket out of blue tube and wood. 5 minute epoxy has lasted for about 25 flights...though it is brittle and cracking in places.

Long story short.... 5 minute will work for a few flights, but will be brittle and eventually fail. Other systems like west, aeropoxy and rocketpoxy have varying qualities, but are in general going to last longer. There are specialized epoxies out there that are fantastic for specific tasks....you'll know when you need them when you get there, and you're not there yet. For this build, Rocketpoxy is the simple answer. easy to use, easy to get.

#### djs

##### Well-Known Member
In addition to the epoxy, you might want to use nitrile gloves, 3mm or 5mm would be good.
This- not just for the exposure, but it's easier to clean up. Nitrile gloves, paper or plastic drinking cups, and plastic spoons to mix with. Also rubbing alcohol can help you get not yet cured epoxy off of anything that you don't want it on. And paper towels

Not much expense, and it makes the job much easier.

#### dhbarr

##### Amateur Professional
This- not just for the exposure, but it's easier to clean up. Nitrile gloves, paper or plastic drinking cups, and plastic spoons to mix with. Also rubbing alcohol can help you get not yet cured epoxy off of anything that you don't want it on. And paper towels

Not much expense, and it makes the job much easier.
Nitrile finger cots are awesome, as well. Glove, cot, cot and you can get 2-3 good finger passes for smoothing, etc.

#### Bluegillbronco2

##### Well-Known Member
Thanks everyone for your advice, you guys are awesome. I will probably go with rocketpoxy.

#### dr wogz

##### Fly caster
Another note for the quick cure epoxies:

The longer the cure time, to more time the epoxy has to run & creep into all the little cracks & crevasses in the surfaces you're bonding. The more cracks & crevasses, and the deeper it gets, the stronger the hold..

The 1:1 mix ratio epoxies usually contain filers to make the mix ratio 1:1. So, you're getting added stuff in the mix..

#### Woody's Workshop

##### Well-Known Member
TRF Supporter
I use "THESE" in 12 & 30 minute cure times.
Very affordable, especially if you order other things from UMRS to max the benefit of shipping charges.
(You have to look at the quantity on each bottle. Advertised 8oz usually means 2, 4 oz bottles.)
Not just on rockets, but anything that needs fixing around the house.
Only time I've had a failure was a butt joint on plastic handle meat cleaver.
Probably because the wife throws it in the dish washer.
But when it failed, I was putting more stress on it than I should have for being repaired.