Any plumbers epoxy experts?

I have a few questions regarding the use of plumbers epoxy (or green stuff) on vehicle customs and hoped I could feed off the experience of some of the guys here. On my workbench is a project that involves basically merging two aircraft together. The front of one sort of slips over the rear of the other. Obviously there will be seams where they meet. That’s were the questions come in. I have decided to fill in the gaps with epoxy putty. The parts will be connected with glued runners on the inside, but there needs to be some hold in the seams as well to avoid cracking. The putty will be the green part shown below:

So, how thin can the putty get and still hold well? I want to feather it in to make the transition as smooth as possible. Also, what level of hardness is generally expected? The putty I am using is something called Mighty-Put with I saw that annoying Oxi-Clean guy hawking on TV. I plan to run a test piece but was curious what others have experienced. Is there opportunity to carve in details after drying? Can the surface be buffed as smooth as the adjoining plastic or will there be a rough finish? I’m assuming once primed it will paint the same as the plastic.

Any help is appreciated.

Cross section of the parts involved

would a small drill bit with a couple of small screws be an option?

would a small drill bit with a couple of small screws be an option?

To hold the parts together or to give the putty something to 'grab'? The parts should be pretty solid, as I am going to lay those stupid plastic strips (that you have the twisty ties go through in the toy packaging) across the interior seams and two-part epoxy them in place. Once dry I had hoped to find the best material to fill in the exterior seams so that I could make the transition from one piece to the next as indistinguishable as possible. The material would need to fill the gap and stay there and look like the exterior of the aircraft is supposed to look. The graphic is pretty crappy, but it is supposed to be a cross-section of where one piece gloves over the other. Then I have to feather it in.

for additional strength, and then do the putty over the screws. i think it might make a difference. im not really well versed in putty use, ive managed to avoid it for the 20 years ive been doing this crap, i figure i should learn one of these days!

Heres what I do when I use Green Stuff or Epoxy putty on Vehicles. What I normally do is where the 2 pieces of each vehicle come together is run a bead of suplerglue along the seam and let it dry. After that is dry I take my putty and fill in all the gaps, over filling the gaps to give your self a good bit it sand down and make the joint look seemless. Also do skimp on the putty, push the putty in the seem as much as possible that way if theres a hold that didn't get filled with the super glue, the putty will get in behind the piece and harden. For the most part the Putty will harden and attach itself to the plastic. Once its hard go ahead dremel it down to just above the finished surface and they use varying grits of sand paper to smooth out the seam. Hope the pics below help you out.

Here is a good example of how I use the green stuff.

Rough Putty:


Dremeled and Sanded Putty:


Finished Product:

Cool. Thanks for the comments guys. I may have to test on some scrap pieces.

What you've got Is NOT the best material for what you want to be doing...Mighty-puti or Plumbers epoxy putty dries rather quickly...which means you don't have a whole lot of time to work the surface and get that clean "fade" you're looking for. Also it really dries rock hard and doesn't sand down very easily... Your best bet would be to work the surface super smoothe before it cures on you.

I've not used Green Stuff...but it, or things like Mili-putt, or any of teh Aves epoxy sculpt like products would prolly work better for what you want to do.

Also...I've found that because vehicle plastic is softer than the hardened epoxy putty's you'll have a difficult time getting a smooth feathered in finish if you don't get it done before the putty cures.

What you've got Is NOT the best material for what you want to be doing...Mighty-puti or Plumbers epoxy putty dries rather quickly...which means you don't have a whole lot of time to work the surface and get that clean "fade" you're looking for. Also it really dries rock hard and doesn't sand down very easily... Your best bet would be to work the surface super smoothe before it cures on you.

I've not used Green Stuff...but it, or things like Mili-putt, or any of teh Aves epoxy sculpt like products would prolly work better for what you want to do.

Also...I've found that because vehicle plastic is softer than the hardened epoxy putty's you'll have a difficult time getting a smooth feathered in finish if you don't get it done before the putty cures.

Just to point out that stuff I use is the actual "Green Stuff" Material which is better to work with than actul plumbers putty. The stuff you get from lowes and places like will cure very fast, where as the Green stuff takes longer to cure and makes it easier to use. After nova mentioned I do remember having a hard time sanding when I used the plumber epoxy compared to the green stuff I have used recently. Like I said before I one I apply the putty to the cracks you are going to fill I will use rough grit dremel bit to sand down most of the epoxy to just above the finished surface and then ill use something 320 sand paper to get it a little more smoother and the finish sand it with some like a 600 grit sand paper.

Thanks for the added information guys. The stuff I actually have is this that my wife decided to order one day. I have not tried it yet as I mentioned. If it dries too hard it sounds like green stuff or miliput is the way to go. We have a Hobby Lobby now, so maybe I can get some using something other than online ordering.

Oh, and I forgot to mention before that Carnages' Hiss flippin' rocks!

I used plumber's epoxy putty for my first 6 or so customs and am very familiar with it. After switching to Aves Apoxie I realized just how un-ideal the plumber's stuff is for this kind of thing. It's not made for sculpting and making things look smooth and pretty, but I managed to make it work because it was cheap and available. It dries very hard, and it's brittle for thinnner applications. It does bond to what you're working, but I found the kind I used could also be pulled off the surface with some small effort the next day. The stuff you have may have better bonding abilities if the marketing's to be believed. It dries very quickly...mine had a longer working time than most and I could squeeze just about 15 minutes of workability out of it before it was too stiff. It can be sanded and dremeled, but you want to do details before it sets because you won't get fine detail out of it once it's cured. It does not blend totally smoothly into the surrounding plastic regardless of how much you sand it. The particles of the compound are just too large. I think your putty might be strong enough, and you might use it for the seam, but then use something meant for sculpting over it for the final finish.

I think your putty might be strong enough, and you might use it for the seam, but then use something meant for sculpting over it for the final finish.

I like that idea. So is green stuff or Aves is likely the best bet for the finishing. Thanks again for all the info. guys.

Hope it's a good idea in the end for you!

I can't speak for green stuff because I've never tried it, but I get great results with the Aves. You might find some helpful tidbits here:
http://www.joecustoms.com/forums/viewtopic.php?f=15&t=11768&p=133473#p133473

Here's a WIP I'm using Aves on, which is the gray stuff. I've done absolutely no sanding or dremeling at this point and the only sanding I anticipate is a couple of spots where it blends into the plastic at the shoulder joint and I didn't get it quite smooth enough.

Picture 139.jpg (136.59 KiB) Viewed 709 times

Wow, I didn't expect the volume of alternatives out there. So far besides my original Mighty Putty products mentioned have been:

Green Stuff
Miliput
Aves Apoxie Sculpt
Prosculpt

Now just to see where to get what. Looks like a stop at Hobby Lobby or Michael's this weekend.