Help: smooth cast 65d is warping under heat

I’ve been slush casting my helmets with 65d for quite some time. But now that the summer time heat is upon us I’ve noticed that some of my smooth cast 65d castings are warping during shipping. I’ve recieved some customer feedback showing backplates they have become misshapen upon arrival and I’m wondering if anything can be done to strengthen the material so it resists heat warp.

Do you use any sort of filler in your castings? I use Urefil (cannot remember the number, might be 7) in my slush-cast helmets and have no issue with accidental warping! Thickens up the resin.
https://www.reynoldsam.com/product/ure-fil-fillers/

drewthecostumer said:

Do you use any sort of filler in your castings? I use Urefil (cannot remember the number, might be 7) in my slush-cast helmets and have no issue with accidental warping! Thickens up the resin.
https://www.reynoldsam.com/product/ure-fil-fillers/

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No fillers were used. I spoke to Reynolds and they suggested I use the 65d as the first coats and then use something like onyx for the final coat to give it some strength.

Previously, I also used smoothcast to rotocast my helmets.
But after some issues with some features warping during summer shipping,
I switch to Onyx. It has a higher heat deflection temperature (212) vs smoothcast (120)
I also added microballoon fillers to help lighten the weight and for more heat resistance.

Reznor9 said:

No fillers were used. I spoke to Reynolds and they suggested I use the 65d as the first coats and then use something like onyx for the final coat to give it some strength.

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While that would probably work, and they're the real experts, the idea of layering different types of resin is setting off red flags in my head :lol
In casting helmets, I generally use four coats of resin in the following order:
8oz 65D
8oz 65D 3oz filler
8oz 65D 4oz filler
8oz 65D 2oz filler

The outside layer is straight resin to get the sharpest pull.

RacerMachX said:

Previously, I also used smoothcast to rotocast my helmets.
But after some issues with some features warping during summer shipping,
I switch to Onyx. It has a higher heat deflection temperature (212) vs smoothcast (120)
I also added microballoon fillers to help lighten the weight and for more heat resistance.

Click to expand...

I operated in the other direction. I used to use onyx exclusively for my helmets but would find that sometimes when removing the flash from the helmets I would run the risk of cracking the pieces through and through. Found out through Reynolds that since onyx has a higher surface strength but less flexibility it is more prone to cracking when impacted or dropped as to where 65d has mkre flex which would allow a dropped item to flex and give it some bounce. So for durability to impact reasons I switched over to 65d. But as you stated in the summer heat it’s showing complications. The layering effect the guy told me gives you the best of both worlds. The drop resistance of 65d and the backing strength of onyx. I’m going to try it and see how it fares as I still have some onyx in my inventory.

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drewthecostumer said:

While that would probably work, and they're the real experts, the idea of layering different types of resin is setting off red flags in my head :lol
In casting helmets, I generally use four coats of resin in the following order:
8oz 65D
8oz 65D 3oz filler
8oz 65D 4oz filler
8oz 65D 2oz filler

The outside layer is straight resin to get the sharpest pull.

Click to expand...

i was looking at the fillers right now. 7 is described as Improves dimensional stability in urethane resins and castable epoxies. Often added to materials to make them flame-resistant
So that might be something I can try as well. Does it change the viscosity of the product and make it harder to rotocast?

Reznor9 said:

i was looking at the fillers right now. 7 is described as Improves dimensional stability in urethane resins and castable epoxies. Often added to materials to make them flame-resistant
So that might be something I can try as well. Does it change the viscosity of the product and make it harder to rotocast?

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I just got off the phone with Reynolds, and I purchased Urefil 3!! Its a ceramic filler.
And yes, changes the viscosity a lot. It'll be more prong to have a lumpy inside.

drewthecostumer said:

I just got off the phone with Reynolds, and I purchased Urefil 3!! Its a ceramic filler.
And yes, changes the viscosity a lot. It'll be more prong to have a lumpy inside.

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It doesn't have to be lumpy. If you are not mixing it in a really high ratio, then you can still slush cast perfectly fine