Devcon Putty - Don't do it!

Alright folks. Having never read any reviews about 2 part Epoxy putty/clays, I decided to try some off-the-shelf stuff tonight. I have sampled some of Apogee's 2-part clay which I found to be excellent, but not having any on hand really makes you desperate to just try something else. Besides, the usage of 2-part epoxy putty/clay seems like the not-so-common technique in rocketry.

The product - Devcon 15 minute to part clay. (Looks like a sausage, the resin and hardener react once the "sausage" is kneaded together.)

The results - crap. This stuff must have one use on this planet, but it is certainly not for rocketry. Kneading the clay together is a tough and stinky job. I was amazed at how foul the odor is considering the Apogee 2-part clay is odorless. I also found the clay to be extremely hard and lumpy. Once there was some sort of consistency to it, I noticed it was already begining to react as I felt some heat. I quickly attempted to apply it to a fin root with little success. Once the clay hardened, you could notice to look on my face to be harder. I could no longer shape it nor smoothen it.

The only pro to this experience is that I was able to literally pull the clay fillet off of the rocket without any damage. Despite the advertised claim that the clay sticks to any surface, I am quite skeptical as I easily yanked a solid piece off.

The moral of the story - purchase some Apogee 2 part clay/putty even if you don't have an immediate need for it. This way, you won't go out and buy some Devcon like a bonehead.

Really though, is there any other company or manufacturer that makes hobby grade 2 part clay/putty epoxy other than Apogee? I had seen some at the hobby shop but haven't had time to pick some up.

I've been getting pretty good results with west systems epoxy
masking tape and a plastic spoon.


I still haven't figured out the benefit of clay type epoxy.It seems a little too dry for strength type purposes

..can it really soak into anything?or is it more for making large fillets over smaller epoxy fillets?

I may have missed it in the post, but what are you using the clay for. For filets, I use PC7 epoxy paste that you can get from ACE Hardware. To smooth it, you just get out your bottle of rubbing alcohol and put some on your finger and it will just slip all over the stuff until the alcohol evaporates. I suppose you could use it for just about anything if needed.

The other thing I used if doing *light*. I got some microballon hobby filler from the RC shop. It's extremely light and can be mixed with water to thin if too thick. Once cured or hardened. I just got back over it with thin CA. Poof, hard as a rock and it works great. My filets on my 2lb Scratch Phoenix are doing with this technique and it flies on H and I motors no problem.

Alan

Originally posted by aadamson
I may have missed it in the post, but what are you using the clay for.
Alan

Click to expand...

Yep, using it for fillets. I know I can always go the liquid 2 part epoxy route, but honestly I am just tired of mixing cups and liquid epoxy for fillets.

For 2 part clay, I use something similar to what Alan suggested. PC-11, which is made by the same company. I'm not sure what the differences are, probably just drying time. I've had good results the few times I've used it so far. It does seem to take quite a while to harden, and I had more than enough working time with it.

For fillets with regular 2 part epoxy, I've been using a 12 minute epoxy. I've gotten pretty good at just using a small craft stick to apply it with, and not having to use a masking tape dam at each end of the fillet.

What about JB Weld? I've never tried it, but it seems like it might be good for fillets. Anyone tried yet?

Eugene...

I don't know where you got the stuff, but it sounds like you got a bad brand or batch. Below is a picture of what I use; it's Oatey Epoxy Putty and I got it at either Home Depot or Lowes. This stuff is VERY soft and is a bit sticky when kneeded together and is more like a 5 minute epoxy. It works well, see the pics I posted of it used as a filler in my Estes BLU-97 Cluster Bomb Model thread. Sands like a dream and easy to use...once again, this stuff is VERY soft.

I also used it for filler on the big Deuce, so I trust it alot.

Here is a pic:

<a target="_blank" href="https://www.rocketryforum.com/reviews/putty.jpg">Epoxy Putty from Lowes</a>

Carl

AWESOME Carl, that stuff is awesome looking! Would you say it is similar to Elmers Fill n' finish, but harder?

Jason

What is a average cost for Epoxy Putty? Say for 1 lb?

Jetra,

Yea, it's more like soft nosecone clay, pretty easy to work with and shape. The only problem is it's potlife/worktime is about 5 minutes. I think I paid $3.99 for the 4oz stick...you can go here to see:

https://www.lowes.com/lkn?action=productDetail&productId=23533-138-31270D

Carl

Originally posted by CTulanko
The only problem is it's potlife/worktime is about 5 minutes. I think I paid $3.99 for the 4oz stick...you can go here to see:

Click to expand...

Carl, How is this stuff activated? How is this packaged? I mean do you have to use all 4oz at one time, or is there a re-useable container?

Rocketmaniac,

The tube you see has two layers...a soft light gray caramel outside with a chewy middle inside...ooops, err...I mean...

Actually the plastic holder tube has a gold paper liner for looks. When you open it, the epoxy comes out as a clay-type rod, which is coated in a fine clear plastic film. the outside of the rod is light gray and the inside center is dark gray. I simply use a razor and slice off a piece I need...pull the clear outer plastic off, then start kneeding it together. Just that easy.

Carl

The stuff I have now is Loctite brand IIRC and is the only type available at the closest Home Depot. It is good to stick shock cords in the tip of cone and do some repairs. It sucks for fillets because, like the stuff eugene is using, is impossible to smooth and is very hard after it sets. There's a lumber yard close by that has a lot of stuff HD and Lowes don't carry here, I'll have to look for some of the recommended brands there.

However, my all time favorite filler is the SuperFil sold by ShadowAero. Its sold in quart tubs (the hardener is a pint). It is super light, sands like fill-n-finish, is nice and hard when set. I have used it for fillets, to fill tube lines, to fill Kevlar sock, as a structural repair to a fin can when the side of the airframe burned up, all kinds of stuff. My only gripe is when you have a huge tub you end up wanting to slather it all over and it goes faster than you think.