Helmet casting?

strider521

New Member
I have a small question what type of resin do you guys use for casting your helmets, I've seen many types but don't know which is best.
 
Some use fiberglass resin as the standard. However, there are some other materials that could be used. Smooth on is another brand that would help create a mold and use their own resin for the helmets. In fact, there are tutorials out there to show you and guide you on how to make it. My main concern is the thickness of the helmet for durability. But that's just me.
 

xXDashIVXx

Sr Member
I have a small question what type of resin do you guys use for casting your helmets, I've seen many types but don't know which is best.
There are some good videos out by punished props and tested that go over this. All the readings out there are different and have certain pros and cons, so doing research to figure out what is ideal for you is key. I plan on using the smooth on onyx fast resin when I make mine
 

gerard2567

Member
If you're going through the fibreglass route-

Epoxy resin has been another form of casting for stronger items with no flex (With a combination of fibreglass). Super rigid and light (Lighter than fibreglass resin casts) This is used commonly in gun stocks and some costuming companies where strength is needed. Macmillan, for example, uses epoxy resins in their rifle stocks. It's more expensive than fibreglass resin but is lighter and stronger I believe.

Fibreglass resin is an industrial form of casting. Basically, really strong, but if it gets crushed or dented, good luck repairing it. This stuff is mainly used on yachts, boats, caravans, cars (occasionally, before they moved to ABS) etc. Super strong with the best fibreglass to resin ratio. Absorbs most impacts but when it doesn't, you have a hole... Solution? Thicker wall. More resin, more fibreglass. Don't go overboard with the resin though, if you use more resin than fibreglass, you can make it too brittle. It's just like wetting a cloth, not soaking it. Soak it near the last layers to tidy up the fibreglass.

For helmets, I suggest using a two-part mold. Lay resin and fibreglass on both sides and let to slightly cure, before combining the mold and then strengthen the seams. Then, slowly build the strength of the entire helmet.

If you're going through the rotational casing route-

Smooth-On's 300 series has been the standard urethane for roto-casting for ages (Rotational casting, as in slushing the liquid around inside the mold)

However durability wise, you may want to try out smooth on's new 65D resin

It's basically a new and cheaper resin which offers better impact resistance than smooth on's 300 series. In other words, superior according to most sources. I haven't tried it myself but based off videos of stress testing. It's insane.

300 will typically shatter if you drop it down a set of staircases. 65D, with at least 7-10mm of wall thickness, should not.

The shore hardness is where things are a little bit more understandable. 300 has a shore hardness of 70 on the D scale. 65D has... 65 on the D scale so it's 5 less than 300 meaning it can flex a bit more, allowing better impact resistance, but it's not like vinyl so it shouldn't be flimsy.

Im not sure what the cons are comparing 300 to 65D. I believe that 65D needs to stay in the mold much longer as it takes a while longer to harden (Based off what I've seen). Removing it to fast can cause some warping issues as it would be soft and malleable.
 
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Fascinating! I was once thinking about using a mold for mass production of helmets, but I don't want the helmets to flex after taking them out. I'm going to have to research their products better to get a more durable helmet that doesn't crack easily.
 

gerard2567

Member
Fascinating! I was once thinking about using a mold for mass production of helmets, but I don't want the helmets to flex after taking them out. I'm going to have to research their products better to get a more durable helmet that doesn't crack easily.

I don't think the flex is that great in the products I've mentioned?

Like, if you squeeze with all your might, it may flex and spring back. That's about it.
 

Dagger06

Well-Known Member
65d will warp in heat. Use 300. It’s plenty durable for its intended use, which hopefully isn’t dropping on the ground >_>

For mass production casting from a silicone mold, SmoothCast 300 roto cast is the industry standard.

(Flex is not a huge difference from 300’s 70D by itself. )
 

gerard2567

Member
65d will warp in heat. Use 300. It’s plenty durable for its intended use, which hopefully isn’t dropping on the ground >_>

For mass production casting from a silicone mold, SmoothCast 300 roto cast is the industry standard.

(Flex is not a huge difference from 300’s 70D by itself. )

How much temperature is needed before it warps? Curious as I know 300 tends to warp upwards around the 120 celcius area
 

xXDashIVXx

Sr Member
Oh! It resets itself! Okay, I got it.
I beleive most of these casting materials flex, but the flex is more of a slight one that is more relatable twards shock absorption rather than a rubber or soft material if you know what I mean. It is still very much rigid and sturdy, but it isnt stiff as a rock
 
I beleive most of these casting materials flex, but the flex is more of a slight one that is more relatable twards shock absorption rather than a rubber or soft material if you know what I mean. It is still very much rigid and sturdy, but it isnt stiff as a rock
Really? The less I know. I will have to keep that in mind.
 

Asgardianhammer

Identity Officer & RCO
Division Staff
405th Regiment Officer
How much temperature is needed before it warps? Curious as I know 300 tends to warp upwards around the 120 celcius area
65D does not need much heat at all to warp. I have seen folks do a couple of coats of 65 then finish with 300.
 

Asgardianhammer

Identity Officer & RCO
Division Staff
405th Regiment Officer
There are some good videos out by punished props and tested that go over this. All the readings out there are different and have certain pros and cons, so doing research to figure out what is ideal for you is key. I plan on using the smooth on onyx fast resin when I make mine
I would not cast a helmet in Onyx Fast. I have and it was a literal Hot mess. Your working time is nonexistent. Even if you refrigerate it. Also Onyx fast will shrink as well so if you have additional parts that can be a problem. Plus the hotter the material you are casting the less likely your mold will hold up over time. Heat is terrible on silicone.
 

Asgardianhammer

Identity Officer & RCO
Division Staff
405th Regiment Officer
Well then aint using 65D in australian summers...
I absolutely would not use that. I live in Alabama and the heat is brutal. Don't get me wrong, I absolutely love 65D but it just is too soft to hold up on its own in heat. When i cast I usually do about 4 rounds of resin total in buckets. The first coat is a smoothing coat that can be done with 65 or 300. My next two coats get a ceramic filler added for extra stability and thickening to work the mold less and the last coat is another smoothing coat.
 
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