Double Casting a thin piece onto another piece, methods?

Kylash · Aug 30, 2018

So yeah this is another 2017 Power Rangers power coin thing, but ive been wracking my brain on this for months and just havent gotten good results so I feel like im missing something obvious.

From what ive determined studying my own production made coin, the main coin body is finished and gold leafed. Then these black rock bits are somehow double cast over that partially finished piece. These auction photos helped me nail that down, as you can see where the double cast resin leaked from the main area of the rock mold and got into the detail lines.

My problem is how do you get such randomized patterns without a ton of molds, and how do you get it so tightly around the existing piece without it leaking all over and making a mess? AND pressure cast it, as I don't see any bubbles in these rocks. These rock parts were done on at least 15 different coins all in varying different sizes and shapes and positions. I can verify from my coin that its hard black resin.

My experiments with partial wrap around molds for these edges with rock shapes ended up with rocks that were mostly bubbles, or resin that leaked through the edge of the mold and wouldnt stay tight to the surface like this.

SlimeTime13 · Sep 1, 2018

To me, it almost looks like it is all one piece. The first coin looks like it was cast in blue resin, with the groves and stones all being blue. Then they were gold leafed and the stones painted black. That's at least what it looks like based on the pictures. I could be way off.

laellee · Sep 2, 2018

Just going from the other way, what if you took a tinted epoxy putty and manually applied to each coin?, fine tuning with wood shaper sticks? Just a shot there, I could see that looking good or looking only 'ok' and being too labor intensive.

Kylash · Sep 2, 2018

I actually did that with the wraparound molds I made, and it works, but I was hoping to figure out how they did it with resin.

cavx · Sep 3, 2018

I can't all the questions, but if the parts were coated in epoxy (which is normally clear and can be tinted any colour), it will -
A form a meniscus and not run off the coin due to surface tension.
B will degass itself as it is only thin.

Mr Mold Maker · Sep 9, 2018

While I’m sure it’s possible to double cast these, it sure doesn’t seem practical.

Did you know they make black super glue? What I would do is make or get yourself a silicone pad with a nice flat surface and premix yourself up a bunch of the “rocks.” Superglue and baby powder. You’ll have pretty fine control over them if you want specific shapes, other wise you can just make random little shapes and clumps. Grab a few, put a little glue around the edges of the coin, place the rocks down, and hit it with some accelerator. The accelerator will temporarily drop the viscosity of the glue allowing it to run into the cracks just a little as you see in the photos. If you want extra texture, add a little more superglue but this time, instead of accelerator, kick it with baking soda. It will form a nice texture, but be careful, it gets super hot.

I am not saying this is how they did it, I don’t know how they did.. but it’s a quick way to mass produce many random patterns and effects as seen on the coins. Best of luck on whatever you end up doing.

robstyle · Sep 14, 2018

The material, are you certain its "resin" and not a hard plastic or casting epoxy? On top of that, are you certain the black, which to my eyes looks painted on in the photos, isnt actually a hard rubber? Many casting materials dont like to bond to one another for various reasons but rubber will stick to most anything. Much of the technique would come down to the shop/person that made them. If its a larger shop that churns out props like walmart, all that misc casting on casting doesnt fit the time frame for the job. Its simply too much work to justify the outcome. If its a smaller shop or indy prop maker, ive seen some crazy things done by that circle of people. A prime example are the light up hero Necro weapons from the Chronicles of Riddick. Those were metal clad castings with machined insides and over the top electronics.

One rule of thumb, dont over think it. Simplify. Movie props are not made for longevity but for moments on screen.

If you recall the War of the Worlds Tom Cruise movie, he picked up a clearish rock and put it in his jacket pocket never to be seen again. That rock was actually a specifically created item with various colors and metallics in the casting. There were some tests using rubber on the surface of the cast rocks to add depth to the casting itself. Although I dont recall seeing the final props before being sent out, I can tell you first hand the rubber on the clearish rock castings went very well.

laellee · Sep 15, 2018

robstyle said:
The material, are you certain its "resin" and not a hard plastic or casting epoxy? On top of that, are you certain the black, which to my eyes looks painted on in the photos, isnt actually a hard rubber? Many casting materials dont like to bond to one another for various reasons but rubber will stick to most anything. Much of the technique would come down to the shop/person that made them. If its a larger shop that churns out props like walmart, all that misc casting on casting doesnt fit the time frame for the job. Its simply too much work to justify the outcome. If its a smaller shop or indy prop maker, ive seen some crazy things done by that circle of people. A prime example are the light up hero Necro weapons from the Chronicles of Riddick. Those were metal clad castings with machined insides and over the top electronics.

One rule of thumb, dont over think it. Simplify. Movie props are not made for longevity but for moments on screen.

If you recall the War of the Worlds Tom Cruise movie, he picked up a clearish rock and put it in his jacket pocket never to be seen again. That rock was actually a specifically created item with various colors and metallics in the casting. There were some tests using rubber on the surface of the cast rocks to add depth to the casting itself. Although I dont recall seeing the final props before being sent out, I can tell you first hand the rubber on the clearish rock castings went very well.

^THIS. So many props and techniques are overthought, a lot of it is stupid. It took me 4 years of reproducing a texture on a part before I found out from Lorne Peterson (on accident) that it was just walnut shells ground up and rubbed into a surface. Nothing wrong with being right, but 'perfect' is subjective..

Double Casting a thin piece onto another piece, methods?

Kylash

Master Member

SlimeTime13

Well-Known Member

laellee

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Kylash

Master Member

cavx

Master Member

Mr Mold Maker

Master Member

robstyle

Master Member

laellee

Master Member

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