Need advice on how to make a copy of an ice cube tray...

[SpiderCircus]

Here's the backstory: The very, very old board game Ice Cube has a tray, seems like cheap plastic, that you pour water into, freeze, and they become the pieces you use to play the game. I have a friend who has this and a different friend who has the game but no ice cube tray. I tried using Oomoo 30, pouring it into the tray, to get a negative mold (I think that's the right term?) and then tried to use Oomoo 30 on that to make a copy of the tray, but that didn't turn out well... the two components fused together into a solid block of Oomoo. Can anyone suggest a way to do this? Thanks in advance!

-Dan

 

[ZeroSum]

Sounds like you didn't use a mold release on the negative mold before pouring on the second batch of Ooomoo. Something like Ease Release ought to do the job. While you're at the Smooth On website, take a look at their tutorials, they're very useful.

 

[martinwilson]

Hi Dan,

Why did you decide to try and make the copy tray out of OOMOO silicone? The only thing that sticks to silicone is silicone - and so trying to cast silicone from a silicone mould requires a good release agent. Almost anything else you could have chosen would have released from your mould no problem without a release agent.

I understand that you need to get the ice cubes out the copy tray - but most casting resins have enough flexibility to allow for that... Resin is also cheaper than silicone - and it would produce a copy that more closely matches the material of the original. I would recommend something like Smooth-On's Smooth-Cast series.

 

[Mr Mold Maker]

I would recommend instead of silicone or urethane resin, try using urethane rubber instead. Cheaper than silicone, flexible, and nice and tough. I wouldn't want to freeze resin repeatedly, and chances are you would have one hell of a hard time getting the ice out.

As stated above, you definitely wanted to use release there casting silicone in silicone.

 

[SpiderCircus]

Thank you for all the responses! I originally tried Silicone rubber because, not having any background, it looked like the material most novelty ice cube trays are made out of, so I figured it would bear repeated freezings well. I have the feeling now that that's not the case. The Oomoo 30 was great for pouring into the ice cube tray piece, since the plastic is old, has a few parts where it's cracking, and I was worried about anything stiffer causing the tray to crack when I tried to release it.

So at this point I have a mold of the inside of the ice cube tray made from Oomoo 30. If I use Urethane rubber to pour onto that (after building a box around it) would that release easily, and would that work well for repeated freezings? And if so, can you suggest a brand/source?

 

[Mr Mold Maker]

Something like Vytaflex 40 from Smooth On will suit the application well. Urethane rubbers and silicone will not generally bond, so release isn't necessary but you can always powder the oomoo mold with some baby powder to help the casting process and aid in releasing a tad. It will do fine in your freezer.

Now again, this is taking it as if the ice cubes are solely for the game.. these materials are not food safe so I wouldn't go plopping the ice cubes in your mouth here..

 

[SpiderCircus]

Well, I went ahead and got Vytaflex 30 (just because it was available near me at the time) and on one hand, it worked really well in terms of viscosity for pouring, on the other hand removing the ice cubes from the tray cause damage to the center portion, meaning I'm not sure how long the tray will last before it doesn't work anymore. Would Vytaflex 40 be strong enough to resist tearing, or should I go directly to 50, or is there another material, like they use for the novelty ice cube trays they sell on amazon, that would work better?

Thank you for all your help on this, I've learned more about molding than I thought possible, and it's awesome to be so close to finishing it. Especially since I'll be seeing the person I'm making it for (as a surprise gift) next month

Also, no worries on food-safe, this will only be for game use, not for eating.

Edit: Here's a picture of the ice cube tray game with the ice cube tray in yellow for reference to the center thing I'm referring to, to hopefully clarify what I mean when I say the center portion tears when pulling the ice cube out.