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Post by jackstraw on Mar 6, 2018 9:18:14 GMT -5
Hello. I'm trying to cast a mold to hold ice sphere cocktails in the freezer. It needs to be a substance that is safe to be direct contact with a consumable, can withstand freezing temperatures, and that won't cause the ice to melt. The commercial mold that i use to create the ice spheres has a rubber/silicone top. This substance works very well. I've had an ice ball cocktail sitting on one of those for more than a week now with no problems so i know the premise is feasible. However, my first attempt was a failure. As a "food-safe" and inexpensive solution i used a combination of unflavored gelatin, glycerin (glycerol), and water. The result was a casting that was soft and rubbery, didn't freeze in the freezer, and a perfect fit for the ice spheres. I thought it was a perfect solution. However, the ice ball melts within several hours of being placed in the holder. Keep in mind that i put the gelatin/glycerin mold in the freezer a full day before using it so there shouldn't be any latent heat hanging around. Oddly, the ice ball melts at the top, not where it comes in contact with the holder. Cost is a bit of a restriction here. I intend to make 2 trays that will hold 8 cocktails each. I will use them for 2 different bar tending events later this summer. After those events i'm not sure that i'll have a use for these. I would prefer not to spend a lot on a casting material if there is an in expensive option. Here are some pictures to better understand what i'm doing: On the left is the top of my commercial ice sphere mold. It works perfectly for storing the cocktail filled hollow ice spheres. On the right is my gelatin/glycerol based casting.  I want to create a casting that will hold 8 cocktails and fit inside a tupperware-style container. I've built this... i just need a substance to fill it with:  Any advice/recommendations you can offer would be greatly appreciated! |
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Post by notoes on Mar 7, 2018 9:46:55 GMT -5
For something that large, you probably won't want to use a "putty" type - you might have better luck with a liquid type silicone. Though I do see Mold Putty 15 is a putty option in the food safe category with a longer open time, I haven't used it myself (I've only used the Amazing Mold Putty) so I can't speak for that one.
I believe Plat 10, 25, and 40 are food grade and are 1:1 ratio by weight or volume and do not need degassing. Plat 55 is also food safe but it has a 10:1 by weight and degassing is recommended. Personally, I don't have any degassing equipment so the 10, 25, and 40 is what I'd go with. Just for the sheer size, I personally would use a liquid silicone. I've used them before in a different brand and have had good results with smaller, more detailed food molds.
Oh and your gelatin/glycerol casting won't hold up because both materials won't really "freeze" - I make gummies a lot and know that both of those materials don't freeze well, they simply stiffen up but never get very firm.
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Post by jackstraw on Mar 7, 2018 10:13:53 GMT -5
Notoes, thanks for the response! I like the idea of using the liquid silicone, but the ones you mentioned are a bit cost prohibitive. They would probably be ideal for this but i can't justify spending $80-$120 on this project. I think that's about how much i'd need to fill those molds.
I liked that about the gelatin/glycerol option... it meant that it stayed soft and offered the ice spheres protection, but i guess since it doesn't actually freeze it maintains some level of latent heat?
Thanks again!
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Post by carol - Alumilite Corp on Mar 7, 2018 19:44:58 GMT -5
Jackstraw,
I would have given the same answer as Notoes about the Plat series. It is easy to work with and would create a nice, food safe, multi cavity mold. Silicone's unfortunately can be a costly way to go in creating a mold, especially when it is one that you only need for short runs.
Regards,
Carol
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Post by notoes on Mar 8, 2018 8:39:32 GMT -5
I completely understand the cost factor, I've got 10 or so small molds I want to make but can't get enough together to order online which is the only way I could get them myself since they're not sold in a store/retail location nearby me. If you can get them, there is a way to stretch the food safe option though it would require a bit of work.
You could cover just the half moon plastic pieces you have there with the Amazing Putty in a very thin layer, and I do mean THIN - such as 1/16" thin but not thin enough in any one area to tear. If you have seen the silicone candy molds in stores, that's about how thin you should go. I say use the Amazing Putty because it's the easiest to get a hold of and cheapest plus you might be able to score a coupon to bring the price down if you go to Hobby Lobby (they always have a 40% off coupon available) or if you're really lucky - Michaels might have a good coupon.
If you do just one half moon at a time (and just the half moon) you should be able to get the putty on before it sets up. Then do another thin layer of putty between the half moon pieces so that they're all connected and you have a layer of food safe material everywhere the food will touch. Then after all the putty fully sets up, you could add in something non-food grade to provide the rest of the support underneath. This way the food grade material is the only stuff touching the food and the non-food stuff can't touch the food because of the food grade material is in the way. Just make sure there are no tears or too thin areas in the food grade putty as this is your "layer of protection". And be careful of what you use as a "filler support", I wouldn't use anything that might be able to seep through somehow to contaminate the putty. Also make sure the Amazing Putty has had a full cure before adding the under-support. I've added different brands and kinds of silicone together to form a mold (when I didn't have enough of one kind to finish) but haven't tried it for a food application though it SHOULD work.
Also two other things you could do to stretch the cost is make the box smaller to go inside a smaller container and so they're not so far apart from each other. Or add more half moons to fill the space more.
Since you plan on leaving the food in the molds, I would say that they need a under-support of some sort but as long as you have the layer of protection, you should have no problem with contamination. I've made a couple thin area candy molds with food grade liquid silicone but those were for food that didn't stay in them for longer than it took for the food to set up. And it takes some work (and a hair dryer) to get the liquid to build up enough on the casting (in your case it would be the half moons) to make it stay in place but also be a thin area.
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