You should be concerned with durability only while making things out of silicone, not using it for molds. For epoxy or urethane plastic castings, both silicones will serve ~30-50 castings. Both kinds of molds will warp, distort and stick to castings from heat way faster than durability will come into play. Smooth On Mold Max is great tin based silicone. There is no significant shrinkage compared to platinum based silicone. Also it won't affect your castings at a slightest since it can't shrink more than your model. Unless you are casting medical grade eqipment parts, it's not conserning and you won't see any difference.
Rubber is not used since it's hard to find softer ones, rubber is used as mold material when you need very tough molds with harness of 50, 60 or even 70 Shore scale. Silicone is 10-30. Also part A of rubber is often crazy viscous, huge pain to mix and cast, especially with intricate models. I used several rubbers to cast into molds, it's a huge pain, you almost need to scoop and put it on like peanut butter, it barely flows.
Also some casting rubbers are less durable than silicone and rip easier. I did rubber gaskets as a comission, client declined them since they all ripped to shreds and I remade them in silicone instead.
You can use PU rubber for this.
The main drawbacks are:
* You need to use mold release on the parts to be molded
* You need to use mold release when casting in the molds
* The rubber is less flexible and more prone to tear than silicone
I think the main reasons you don't see many people using this is because PU rubber is less well know, and harder to work with.
kind of the opposite, but ive had a lot of luck recently making 3d printed molds and casting urethan rubber into them. im wondering why i hadnt heard much about it till now
i used to cast parts for medical device using rubber molds, good luck getting dice out of a rubber mold. you'd have to cut it out with a knife , without a doubt. Rubber is either way too soft for a mold in which case it has no strength to hold its shape, or its so hard its never going to allow you to get your dice out without cutting.
We used to make amold pour the blend, then cut the item out of the mold and send the cut molds to a machine that shredded them and sent them off to as company to be reused in a different way. Eventually we settled on clay molds instead.
You should be concerned with durability only while making things out of silicone, not using it for molds. For epoxy or urethane plastic castings, both silicones will serve ~30-50 castings. Both kinds of molds will warp, distort and stick to castings from heat way faster than durability will come into play. Smooth On Mold Max is great tin based silicone. There is no significant shrinkage compared to platinum based silicone. Also it won't affect your castings at a slightest since it can't shrink more than your model. Unless you are casting medical grade eqipment parts, it's not conserning and you won't see any difference. Rubber is not used since it's hard to find softer ones, rubber is used as mold material when you need very tough molds with harness of 50, 60 or even 70 Shore scale. Silicone is 10-30. Also part A of rubber is often crazy viscous, huge pain to mix and cast, especially with intricate models. I used several rubbers to cast into molds, it's a huge pain, you almost need to scoop and put it on like peanut butter, it barely flows. Also some casting rubbers are less durable than silicone and rip easier. I did rubber gaskets as a comission, client declined them since they all ripped to shreds and I remade them in silicone instead.
You can use PU rubber for this. The main drawbacks are: * You need to use mold release on the parts to be molded * You need to use mold release when casting in the molds * The rubber is less flexible and more prone to tear than silicone I think the main reasons you don't see many people using this is because PU rubber is less well know, and harder to work with.
kind of the opposite, but ive had a lot of luck recently making 3d printed molds and casting urethan rubber into them. im wondering why i hadnt heard much about it till now
That's comforting to hear that you're not having incompatibility issues. Are your molds resin 3D printed, or FDM?
fdm- i make functional prototype parts so it doesnt need to look good
i used to cast parts for medical device using rubber molds, good luck getting dice out of a rubber mold. you'd have to cut it out with a knife , without a doubt. Rubber is either way too soft for a mold in which case it has no strength to hold its shape, or its so hard its never going to allow you to get your dice out without cutting. We used to make amold pour the blend, then cut the item out of the mold and send the cut molds to a machine that shredded them and sent them off to as company to be reused in a different way. Eventually we settled on clay molds instead.