How to plastic coat foam costume pieces

Im back to pick your brain again mr xrobot :)

Just looking on the curetime website and noticing the 300 series smooth cast stuff.

What made you decide to choose 65d over some of the 300 series stuff?
For example: smooth-cast 305 (found here) has a pot life of 7 minutes which seems slightly more appropriate than the 2 and a half minute pot life of 65d (Here). It says its hardness is 70d (which seems almost the same). Would the application be affected by the slower cure time? Or does the actual stuff have different properties? Was 65d just a random choice?

Then on a different note all together is a product called shell shock (here) Which is described as: "A BRUSHABLE SELF THICKENING URETHANE PLASTIC. Shell Shock creates a tough surface and captures high detail..." This one seems like it would be a good choice too. 8 minute pot life, but on the down side, 5 hours cure time :(


Please forgive my naivety, I literally know nothing about casting stuff and Im hoping you have the answers to my brain pickling problems. I dont want to spend the cash then find out I've bought the complete wrong stuff.
 
Yes, I used 65D because I had some - also as it's designed for rotocasting it cures slowly from liquid to gel to solid which means that the surface should level itself out as it does so.

You could try the 300 series resins but I've never tried them, I've never tried shell shock either.... my main point with the video etc was that Polyurethane sticks to foam as long as you have PVA in the middle - there may be better products for a better finish, it's really good to see other people taking the idea forward and trying different things
 
I am very tempted to give 305 a try. I'll continue with the remainder of the 65d i have left then try that stuff. I hope someone else can comment in the meantime in case its very wrong. Never know, by the time I finish with the 65d, I might be better at it.
 
Xrobots i'm curious if you or anyone else has had the problem where you coat the piece in plastic and once it cures it becomes sticky instead of a hard plastic. It usually happens to me on the 2nd or 3rd coat. Do you know what causes this or how to prevent it from happening?
 
Ive not had the above problem. It may be due to having more of one part than the other.

I just bought 2 syringes off ebay. 50ml each. I think I'll start by using 10ml of each part mixed together. I think its a good idea to work in small amounts. Apply that much then mix up another 20ml, then apply that then mix up another 20ml. Keep overlapping while the previous coat is drying. This is my plan :)
 
Ive not had the above problem. It may be due to having more of one part than the other.

I just bought 2 syringes off ebay. 50ml each. I think I'll start by using 10ml of each part mixed together. I think its a good idea to work in small amounts. Apply that much then mix up another 20ml, then apply that then mix up another 20ml. Keep overlapping while the previous coat is drying. This is my plan :)

I have been using a similar process. I bought two turkey basters and measure out the amout i'm using for each part. I've only been working in max quantities of 3/4 of an ounce. I haven't tried overlapping the layers for fear upsetting the part that is drying. I think i might call the support line and see if they have any suggestions.
 
Xrobot suggested layering before the previous layer dries completely so that each layer blends. I haven't tried it yet but I trust his word. Do you have any pictures of your progress?
 
Yes- you ideally need to keep layering up before the last coat has cured properly so that they all bind together.

The only time I've had issues with the 65D curing was the time I forgot to shake the bottles up as instructed before using it...
 
Typically you get the tacky effect if you improperly mix ratios of A and B. You can try salvaging it by lightly painting on the hardening agent (I think this is generally part A for smooth-on products), but it's pretty hit and miss.
 
Also I want to second that using the 1/2" interlocking EVA mats are not going to end well. I've scrapped two chest pieces and a shin with my War Machine build before I decided to look into the thinner foam that comes in rolls. I know that Harbor Freight sells the 1/2" thick mats for really cheap, but you will not get the results you're wanting from material that thick.
 
I just started my first costume build ever actually and I am using EVA foam for the majority of it so this will help me immensely
 
Maybe apply thin coats in sections over the helmet/piece...

It will stick to itself because I've used it to cast solid pieces in multiple passes - sometimes up to 8 layers. You just need to apply it ideally before the last coat is fully set. The 65D sets slowly over about 10 minutes - is this what you're using?

In the example video I did lightly sand the first coat before applying the second one, which may have given it a 'key' to stick to.

There's another project going on where the person has made this work on large pieces:

http://www.therpf.com/f24/iron-man-mk4-plastic-coated-foam-build-150770/

Post 5 has more details:

http://www.therpf.com/f24/iron-man-mk4-plastic-coated-foam-build-150770/#post2303970
Thanks for all the work, and for sharing your knowledge!
 
Yes- you ideally need to keep layering up before the last coat has cured properly so that they all bind together.

The only time I've had issues with the 65D curing was the time I forgot to shake the bottles up as instructed before using it...


A-ha! :facepalm I see now where I goofed. I let the layers dry before adding the next and when I went to sand and detail, it more or less chipped or peeled off because it did not stick to the layer underneath. SO.. 'Before it fully cures', do the next layer and so on. Check! :love Thanks for your tutorial on all this. It's a great new tool to use.
 
Has anyone tried this method using a thickening agent in the resin, such as talcum powder, wood powder or cabosil?
I am curious if you would avoid brushing so many layers that way.
 
I just did a Heimdall helmet this way yesterday - built out of a combo of styrene, expanded PVC foam, craft foam (the really thin foam we've got here in the US sold at craft stores) and the thicker floor mats from Harbor Freight.

When I first saw this video, I went and tried some 65D on scraps of all my foam, no glue first.

It bonds to craft foam flawlessly. And as XRobots pointed out, if you only do a layer or two, it stays "floppy" - bad for helmets, possibly awesome for other applications. It'll make a mess of the thicker foam, unless you sand it first. If the surface has been a little roughed up (not enough to give it texture, just enough to "break the skin" so to speak) it'll bond as well.

I haven't had any issues with resin reacting with the PVC (forgot about that when I started, and got 65D all over some bits) - but it does just flake right off if you so much as look at it funny. On styrene, however, it bonds almost like it would to itself. So in my helmet I tried to keep the glue off the styrene parts.

And I'm not sure why you'd want to thicken it up - the idea of multiple coats is:
1) to keep things as smooth as possible (I have chunks looking like 7sinz that'll need some serious sanding)
2) it cures faster the more of it you use at once, and you already have little time to brush this stuff out as is.

I've noticed that on really compound shapes, like your helmets, or anything basically "box" shaped, that you need very little resin to make it good and solid. As long as it can reinforce itself, you don't have to go crazy with it.
 
Oh, and thanks a million for this XRobots! My girlfriend actually sent me the link to your video a few weeks ago - it's totally changed how I'm making my current suit of armor (infinitely easier this way)! I just happened across the thread accidentally, while trying to find somewhere to purchase foam by the roll.
 
I just did a Heimdall helmet this way yesterday - built out of a combo of styrene, expanded PVC foam, craft foam (the really thin foam we've got here in the US sold at craft stores) and the thicker floor mats from Harbor Freight.

When I first saw this video, I went and tried some 65D on scraps of all my foam, no glue first.

It bonds to craft foam flawlessly. And as XRobots pointed out, if you only do a layer or two, it stays "floppy" - bad for helmets, possibly awesome for other applications. It'll make a mess of the thicker foam, unless you sand it first. If the surface has been a little roughed up (not enough to give it texture, just enough to "break the skin" so to speak) it'll bond as well.

I haven't had any issues with resin reacting with the PVC (forgot about that when I started, and got 65D all over some bits) - but it does just flake right off if you so much as look at it funny. On styrene, however, it bonds almost like it would to itself. So in my helmet I tried to keep the glue off the styrene parts.

And I'm not sure why you'd want to thicken it up - the idea of multiple coats is:
1) to keep things as smooth as possible (I have chunks looking like 7sinz that'll need some serious sanding)
2) it cures faster the more of it you use at once, and you already have little time to brush this stuff out as is.

I've noticed that on really compound shapes, like your helmets, or anything basically "box" shaped, that you need very little resin to make it good and solid. As long as it can reinforce itself, you don't have to go crazy with it.

Good work - It's good to see people testing the idea on different materials.
 
My landlord makes backgammon boards as a hobby. He uses a polyurethane spray as part of the process. And it got me to thinking and therefore, experimenting.

So after 3 coats of PVA, 2 coats of the spray, some filler primer and after filling the larger gaps with vinyl spackle, some sanding, more primer, more sanding and primer and sanding, this is how it looks so far (excuse the crappy cell phone pics):
 
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In your video I noticed you use a paint brush to spread it on, did you have any problems with bristles getting stuck into the Resin? I tried to avoid that problem by using foam brushes to apply the resin but makes it hard to get the resin uniformly spread around edges and hard corners.
 
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