Silicone mold options

[ERen89]

In the past I have gotten smooth on rebound 25 trial kits. And it works great of course.

My question is, do you guys opt for a different and more budget friendly material/brand if you don't plan to make multiple casts?

I'm working on a sculpt right now I want to cast in resin, and I know silicone is pricey no matter what. I'm curious, however, to know if you guys approach things differently when material shopping and knowing it'll be for a lot of castings vs a mold that will only be used once?

 

[udog]

I do. When there are not many castings to be made I use tin silicone instead of platinum (like Rebound) as it's a bit cheaper. It also depends on the job you're into. Platinum has negible contraction rate, tin has some contraction depending on the silicone and platinum lasts a bit longer with PU resin castings and has longer shelf life. Also if you look for it you might find cheaper platinum and tin silicones out there depending on the manufacturer. Not always the same quality of course.
For me the main difference to choose is if I'm making a working mold for a large series casting or not.
Another option is urethane rubber, cheaper too but you will need to use release agents or it will bond to resin and almost anything. Not always worth it in my opinion.

 

[ERen89]

Ah yes. I usually tend to stick with smooth on because of being familiar with them almost exclusively. At this moment I'm mostly going to be sculpting to build up skill and experience (same goes with molding and casting) So each thing I make is really just going to have one single copy.

If anyone has recommendations of other manufacturers of mold and casting materials for someone in my position, by all means, send em my way!

 

[udog]

Ah yes. I usually tend to stick with smooth on because of being familiar with them almost exclusively. At this moment I'm mostly going to be sculpting to build up skill and experience (same goes with molding and casting) So each thing I make is really just going to have one single copy.

If anyone has recommendations of other manufacturers of mold and casting materials for someone in my position, by all means, send em my way!

Smooth On has good materials. I would go for a tin silicone if it's just one copy. It's a bit cheaper. Were are you located?

 

[ERen89]

I'm Chicagoland area

 

[udog]

Sorry, I'm in Europe. Here I could tell you some places. Let's see if anyone in the US can help, there are many suppliers and references. In any case if you search Tin SIlicone in the US I'm sure you will find many. Once you find them you can ask here about the particular references to know which one suits better. Looking at the Tech Data sheet gives valuable info about them.
I recall these guys

Tin-Cure Silicone Rubbers | Raw Material Suppliers

Affordable, high quality tin-cured silicone rubbers for mold making applications - available with varying catalysts for slow, medium and fast cure times.

www.rawmaterialsuppliers.com

And someone mentioned this company here, sometime ago.

Tin Silicone Rubber

Tin silicone rubber is a silicone mold making rubber ideal for making / casting molds for epoxy resin, concrete, candle, and any other industrial applictaion use etc.

www.bestbuysilicone.com

But there are more for sure.

 

[ERen89]

Awesome, thanks!

I've got some research to do.

 

[animator]

It looks like there is a Reynolds Advanced Materials store in Chicago. They are owned by Smooth-On and should be a fantastic place to get advice on options for supplies and such. I would be worth visiting them.
I always start a project with a visit to my local Reynolds store and discuss what I am planning with them. It has saved me a lot of money in mistakes and waisted materials.

 

[ERen89]

I have gone there for the first time this past halloween and it was heaven. But that's sort of what has got me looking into a more affordable approach because of how much money I spent.

 

[animator]

I have gone there for the first time this past halloween and it was heaven. But that's sort of what has got me looking into a more affordable approach because of how much money I spent.

Yup, it's super expensive stuff!

 

[clonesix]

Hmmm? The question is “Do I switch $$materials if I only want 1cast?”

Answer: No, I find a material I like, and I stay with it. I will alter my molding technique to reduce cost.

Example:

1. Adding old rubber to the mix
2. Reducing thickness of the mold walls. (Not to be done by beginners). This takes experience so that you don’t distort the casting.


In the end, your project depends on a good mold, whether 1 casting, or 20. Don’t cheat all your hard work by screwing up the mold.

 

[udog]

Hmmm? The question is “Do I switch $$materials if I only want 1cast?”

Answer: No, I find a material I like, and I stay with it. I will alter my molding technique to reduce cost.

Example:

1. Adding old rubber to the mix
2. Reducing thickness of the mold walls. (Not to be done by beginners). This takes experience so that you don’t distort the casting.


In the end, your project depends on a good mold, whether 1 casting, or 20. Don’t cheat all your hard work by screwing up the mold.

True, if you like a material and know it, no reason for switching. But if there is a budget issue it can be considered. I don´t necessarily use the same material (and kind of mold) if I´m making a working mold for a large series casting than if I'm commissioned a single casting or I'm after a transition mold.
Platinum silicone is the best one can find for most things, but Tin silicone can be ok too if one's not expecting a very long shelf life for the mold or if the contraction is not that important among other reasons. In fact it was the standard before platinum came to our studios.
All in all I agree with you, I preffer sticking to the best materials I know how to use. And good materials are usually more expensive. Cheap materials can bring problems.
Also, if we are talking about small molds it might not be worth it as the money you will save is very little. But when talking about a big brush up mold, it can make the difference budget wise.

 

[udog]

1. Adding old rubber to the mix
2. Reducing thickness of the mold walls. (Not to be done by beginners). This takes experience so that you don’t distort the casting.

That's a good idea. I always have grinded silicone for block pour molds.
And cavity pour molds are another good option, but as you say needs skills

 

[ERen89]

That's a good idea. I always have grinded silicone for block pour molds.
And cavity pour molds are another good option, but as you say needs skills

Never considered the old rubber. I have some silicone molds of old halloween masks I won't be using again. Is there any interaction with platinum and tin if mixed? Let's say I have an old, cured platinum mold I cut up and toss in the new mold and fill tin silicone all around it. Would I have some issues or would it blend together just fine?

 

[udog]

Ground Tin silicone into platinum won't work work well in any case, nor working with platinum over tin. Platinum will inhibit this way, doesn't like tin's alcohols. I've never tried to put cured platinum into tin, it could work. But I'd use the same ground silicone in the same kind of silicone just to make sure. Makes more sense to me.
In my case I use this for pour block molds to get more volume using less silicone. You can use it for brush up silicone but getting it smooth might be more difficult and not save that much material at the end depending on how you do it.
You are using the old silicone as a filler. Most probably it won't bond chemically as the ground silicone is already cured. So I don't think just cutting silicone will do, you must grind it with a meat grinder for example, as thin as posible. Ole manual ones work, or electric. Putting in big junks might give some sort of delamination or even bubbles. You need to get a homogeneous mix of new and ground silicone to pour.
Maybe it would be good if you explained what kind of sculpt or sculpts you are going to mold. Material, size etc. and that way figure our what are the options. As said above, sometimes trying to save some money is not worth it all in all.

 

[ERen89]

Ground Tin silicone into platinum won't work work well in any case, nor working with platinum over tin. Platinum will inhibit this way, doesn't like tin's alcohols. I've never tried to put cured platinum into tin, it could work. But I'd use the same ground silicone in the same kind of silicone just to make sure. Makes more sense to me.
In my case I use this for pour block molds to get more volume using less silicone. You can use it for brush up silicone but getting it smooth might be more difficult and not save that much material at the end depending on how you do it.
You are using the old silicone as a filler. Most probably it won't bond chemically as the ground silicone is already cured. So I don't think just cutting silicone will do, you must grind it with a meat grinder for example, as thin as posible. Ole manual ones work, or electric. Putting in big junks might give some sort of delamination or even bubbles. You need to get a homogeneous mix of new and ground silicone to pour.
Maybe it would be good if you explained what kind of sculpt or sculpts you are going to mold. Material, size etc. and that way figure our what are the options. As said above, sometimes trying to save some money is not worth it all in all.

So right now I'm sculpting a Pokemon (Charizard) bust/statue. I will likely cast it in smooth cast, but I want to revisit all the casting options again. I know I want it in a plastic form hence the silicone mold. The sculpt is about 12" tall. Just his head and neck.

 

[udog]

If I got my numbers right 12" is around 30cm tall (I'm in the metric system realm) it's big for a block pour mold in my opinion, lot's of silicone. A brush up mold with a plaster or fiberlass (or others) case could do better in my opinion.
If you are familiar with brush up molds and silicone (if not, worth giving it a go) I would use a Tin silicone that has a good thickener. Platinum will work too as long as what your are sculpting the model with does not inhibit. But tin is cheaper.
Cavity pour molds are good for controlling thickness and are better than brush up for small/medium sized molds in many senses, but need skills. Maybe an overkill.
Platinum: Better general physical properties, larger shelf life once cured, a bit more durable casting PU resin. Negilible ontraction. Can inhibit if not working properly with it.
Tin: Less tear strength, stretchiness. Some contraction depending on brand. Less shelf life once cured. No major inhibition issues. A bit less durable than platinum when casting PU resin.
It´s up to your budget and what you expect. But for one single casting, Tin will work for sure. If the mold is properly done and the silicone chosen is fairly good you will able to cast more too. It will depend on the silicone price.
As for the casting, smooth cast is great but I'm sure finding cheaper options won't be so hard. There are cheaper good resins around for sure. Search in the US, you should find them.

 

[ERen89]

If I got my numbers right 12" is around 30cm tall (I'm in the metric system realm) it's big for a block pour mold in my opinion, lot's of silicone. A brush up mold with a plaster or fiberlass (or others) case could do better in my opinion.
If you are familiar with brush up molds and silicone (if not, worth giving it a go) I would use a Tin silicone that has a good thickener. Platinum will work too as long as what your are sculpting the model with does not inhibit. But tin is cheaper.
Cavity pour molds are good for controlling thickness and are better than brush up for small/medium sized molds in many senses, but need skills. Maybe an overkill.
Platinum: Better general physical properties, larger shelf life once cured, a bit more durable casting PU resin. Negilible ontraction. Can inhibit if not working properly with it.
Tin: Less tear strength, stretchiness. Some contraction depending on brand. Less shelf life once cured. No major inhibition issues. A bit less durable than platinum when casting PU resin.
It´s up to your budget and what you expect. But for one single casting, Tin will work for sure. If the mold is properly done and the silicone chosen is fairly good you will able to cast more too. It will depend on the silicone price.
As for the casting, smooth cast is great but I'm sure finding cheaper options won't be so hard. There are cheaper good resins around for sure. Search in the US, you should find them.

Fortunately I do have some experience with this process. The first couple halloween masks I made I used smooth on rebound and thi-vex thickening agent. And just used plaster for an outer shell. However it was a half mask so I was able to peel it off.

I've seen smaller silicone molds made where you just cut a zig zag down the wall of the silicone mold to release the sculpture/cast. Would you do this for a larger piece too? I'm trying to picture where I'd make the cut.

Also for a better visual reference, here is my WIP. Still a lot to do before making the mold.

 

[SuperBoom]

Was perusing my emails this morning and this thread piqued my interest. Many years ago, I was doing a torso cast off a sculpt-over and needed a sh!t ton of silicone. Just for that one job, it would have been over $500 in silicone (more like $1500+ today for reference), so I ended up going clever but thrifty and thinned down 100% silicone caulk with MEK, round about 50-50. I still use that method to this day when doing silicone casts and pours, and it's Tons cheaper, even with the slightly more elevated cost of caulk. You used to be able to get contracter 6 packs for $11, now it's more like 2-3 singles for the same price.
If you decide the go this route, the silicone pours just like store bought, you can tint each master a different color for identification and library use, and they last a looong time. Also advisable to use a VOC-respirator around the MEK and very effective ventilation. Definitely not a skin-safe alternative so not a lifecast use, but everything else is game.
You can also buff the mix with microballoons for viscosity modifiers, space-saving mixing, or what I tend to do is lay up non-essential areas with clay which separates nicely from the silicone. It does need to be 100% silicone caulk for this to work, no partials or mixed materials with the caulk. I've also tried this with other solvents like acetone and such, but MEK has been far and away the most reliable for ease of mixing and cost-wise. The last time I tried acetone, it took two hours of stirring and sit time and didn't work at all with that brand. After that, I go GE 100% silicone and MEK.

 

[DarkHelmet]

I usually use the Polytek brand and buy from Brick in the Yard in TX.

I recently molded resin gorilla hands to make into latex hands for my Gorilla Suit project. I knew it would take a lot of silicone so I came across BBDINO on Amazon. Not cheap but definitely more affordable than the same amount needed if I were to use Smooth-On or Polytek.

It's a Platinum based silicone with more of a ballistic gel look, but it worked great. It has a thinner viscosity and self gasses and captures amazing detail.