Yes, another question on Casting (need product refferels)

The Armorer

The Armorer

Well-Known Member
Okay everyone, here's another series of questions that may yield little to no results (on my end). I'm looking into casting silicones and resins. Which product would be the best for casting a hard piece (for example, a halo style helmet) and other hard product yielding plastic pieces.

Smooth On. I understand they are THE people to get the casting materiels from, but as you can see from their site: Smooth-On, Inc. - Mold Making & Casting Materials Rubber, Plastic, Lifecasting, and More
There's A LOT of products to choose from, so, as a part of my research (into looking into finding a way to make this hobby of mine to be self sufficient), I'm asking all of the great sculpture and casting artists out there, what would be the best silicones to use for the jacket molds, what type of Release Agents should I use, what casting resins, and generally, any other advice you could give me handling these materials would be most helpful. I may not buy any of these for a while, but it's some knowledge I'd like to obtain as I know little to nothing on the subject.

Much thanks,

Seth/ The Armorer
 
It's a hard question as there is no single 'best' silicone or resin. The reason there are so many products is because there are so many casting requirements. Silicones are measured in the their hardness (shore), tear resistance, and pot life. If your item is complicated with undercuts and requires a mother mould, then perhaps a softer sillicone might be needed but with a high tear resistance. But if you are making a block mould then a slightly harder silicon might be better, and if the item is fairly smooth then the tear resistance isn't as much of an issue. If you are brushing the silicone on, then you might want it to gel in 15-20miutes so you are't forever scooping silcone back onto the item... if it's block then you can just pour it and leave it to cure overnight.

When it comes to resins, I think mostly about pot life and viscosity. If the part you are casting is full of intricate details then a thinner (less viscos) resin might be better so that it can get into the details better. You can even brush or pour an initial thin coat and then add a filler to bulk the resin out. If the item is not very complex you might be able to pour the resin straight into the mould without any worries... then a fast curing resin could be in order. If you need to paint in a layer of resin first, you might need a longer pot life.

So in the end you need to think about what you are moulding and casting and choose, as best as you can, the silicone and resin that you think is best suited to the task.

Don't worry too much about it though, personally I've never bought anything I've not been able to use. Also, try Smooth-on's customer service, tell them what you want to cast and ask for their advice. I've done that before with other companies when I've not been sure of their products.

When it comes to handling, always wear gloves... polyurethane resins can be nasty if they get on your skin. When I first started I didn't wear gloves and got the isocyanate on my hands which I just wiped off. Over the next day or two the skin darkened and peeled off like when you have sunburn. Luckily there was no lasting damage, but I always wore gloves after that. Eye protection is wise (I once put a bottle down a little too hard and a jet of polyol hit me in the face). I also wear a filter mask if I'm casting a lot of stuff, and especially if I'm slush casting, just to be on the safe side. Remember, it can be the accumulative effects of these chemicals that is dangerous, so while getting a whiff is fine, breathing the vapour from curing resin over hours or days or weeks, could damage your health. It's probably always a good idea to read the health and safety sheet for any product that you are going to be using.
 
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I think I'm confused with your wording- you want to cast with both silicone and resin- or you want to have it cast out of resin, so you are using silicone to mold your piece?

Alaneye gave you a lot of good information- there's only a couple things I can think to add.

Main thing with silicone is do you want platinum or tin based. If its going on skin, like a appliance, or your using it to mold food items- it needs to be platinum. Tin based silicones secrete something that is poisonous to humans, so if anything is going to be worn or eaten from it needs to be platinum. However, if all you are needing to do is get a mold for a halo helmet, tin based is the way to go, it's much cheaper, and a much more forgiving material.

For your resin choice, I'm guessing you are going to want to do a slush cast for a halo helmet. Really all you want to make sure of is to get something with a short pot life, otherwise your arms are going to be pissed that you've been rotating something around for 10-20 mins. Most resins stick to themselves no problem after curing, so there's no reason to be afraid of a short pot life.
Also if you want to go cheaper you can do a 50/50 mix of bondo and fiberglass resin. Slush it around just the same.

Hope that's helps with some of your questions
 
Thank you both AlanEye and TessLeah, both of your posts have been extremely enlightening.

I have watched video's of how artists like Adam Gumbo (I think that's how you spell his name... of Blue Realm Studios and one of the original creators of the 405th) have used a rubber plastic that I think was silicone based, to create a mold jacket that would be separated across the top (Mohawk style) which was how it was pulled off the helmets themselves without tearing the jacket.

The resin was for casting, and from what was said in one of Adam's tutorials, that it was needed to be brushed over the entire mould in layers? to give it a uniform thickness.

Like I said, I don't know a whole lot about this subject, I don't know how it would work being used on a solid piece (in the video he covered a clay sculpt), and what I would be covering would be a finished Bondo helmet.

Hope that cleared up my questions in better terms.

Thanks guys :)

-Seth
 
Do you mean you want to cast from a bondo made sculpt? -- The first simple rule of casting is 'hard into soft' and 'soft into hard' , so a 'hard' helmet has a 'soft' rubber cast and vice-versa both AlanEye and TessLeah offer good practical advice , moulding and casting does use some very unpleasant nasty chemicals, so ALWAYS use safety gear " gloves , goggles and mask" before doing anything and make sure there's adequate ventilation - do it outside if you can! Because there are so many variants to both , different products work best for different things, get a good platignum sillicon RTV, ( Room Temperature Vulcanising ) - meaning it 'sets' at room temperature ) same with the poly casting resin , you want a reasonable pot life 3 to 5 minutes and fairly fast casting 5 to 10 minutes for most general work , then you can go onto the more specialised products say for casting face masks etc
 
Ah, it was late when I posted last night, somehow I didn't take in that it was a Halo helmet you were thinking of doing.

If you plan on wearing the helmet then brushing in layers is probably the way to go. When you slush cast there comes a point when the resin begins to cure and as the resin thickens you get a sort of slow ooze, a bit like you see in lava flows, where the resin gathers and slowly moves. That 'edge' of the flowing resin usually sets like that, in a thicker layer which you probably wouldn't want inside your finished helmet.
 
Jumping in where I have no expertise, I think he is asking about a "mother mold" or "mold jacket" to go outside the RTV silicone layer to support it and allow it to be less thick and therefore less expensive.

Seth, is that right?

Jumping back out again to let the experts advise on exactly what materials to use!
 
Your thread is amazing... but it's not quite what I'm looking into. The molds though pretty much uses the same pink stuff (yeah, I'm a casting noob, I just said pink stuff XD), but not the fiberglass.

The process I have seen (which for the life of me I CANNOT FIND!!!! :( ), started with cover the helmet with the 'pink stuff', then separating it into two pieces and wedging tabs (or if anyone's a carpenter, biscuit like pieces, or playing cards...) and then applying several more layers of another plastic (that looked very much the same), then after all of it had set up, the mold was cut open down the seams and then pulled off the helmet, not damaging the original at all. Then, the mold jacket was clamped back together and resin was brushed inside the entire mold in two or three layers to conserve product.

I really wish I could find the link, but I think it was Smooth Cast 300 or 320... like I said, I REALLY need help in this department, I really want to look into making things cost effective for me to build props (then I would silence all of my doubters and make some money to make more :p ).

I REALLY appreciate ALL of the comments, just from the questions I'm learning A HUGE amount of info. :)

The helmet would then be a 'raw' cast and would need some sanding and filling, but would in essence be the exact same thing. Thanks Ladies and Gentlemen for the comments, hopefully I'll be able to sort this out :)

-The Armorer
 
Thank you Alaneye :)

Seth, we are only here to help, it's a lot to take in at first- and as the saying goes there's a thousand ways to skin a cat. Let me try to make it simpler for you, for what I think you are getting confused on.


First off you are talking about two processes. You have the sculpt- whether it be out of clay or pepekura or whatever, that is the original piece or the sculpt.
You are then going to MOLD your sculpt. Molding is when you are making a negative copy of something, no matter the material it's out of.
Then is the CASTING. This is when you take your negative mold and pour another material inside it, making a copy of your original.

The "pink stuff" is either a silicone or urethane rubber, I'm guessing silicone. I used Rebound 25 because its a brush on silicone. You can use that or mold max 30, but be sure to also get thi-vex which is a silicone thickening agent.
They used playing cards, which is great- I didn't want to risk cutting into my mold and weakening it so I made a clay wall- same exact thing different method.
The "white stuff" you are probably right on the money with it being Smooth cast 300. If you want to use that- then go for it, works perfect. Fiberglass works perfect too. You could even use stone like ultracal (however that starts to get really heavy so opt for one of the other two) It just needs to be a rigid material that will hold the shape so the silicone won't get distorted when you get to the casting part.

From what you wrote my thread is the process you are looking for, just not the materials. My mold is a brush up silicone mold with a two part fiberglass mother mold. I clamped it together by drilling holes and using wing nuts to hold the two fiberglass pieces together.

Hope that helps, and if not that you can find the thread at some point to have it make more sense to you. Hope to see some of your work soon!
 
Seth, as TessLaeh says, there are lots of ways to approach the moulding and casting of a helmet, and if you succeed in getting a resin copy out of that mould then that method works. I could probably tell you 3 or 4 ways you could do it... and none of them is the 'right'. The method you read about is the method that person used and he could have mixed and matched the techniques from any or all of the ways that I could tell you... the point being, that if you can't find the thread you saw, then all you will get from here is a best guess of what they did... but, right here on the RPF is a method you can see works, and the creator of that thread is right here too speaking to you, so if you have any indepth questions, I'm sure they will be answered.
 
TessLaeh said:
Thank you Alaneye :)

Seth, we are only here to help, it's a lot to take in at first- and as the saying goes there's a thousand ways to skin a cat. Let me try to make it simpler for you, for what I think you are getting confused on.


First off you are talking about two processes. You have the sculpt- whether it be out of clay or pepekura or whatever, that is the original piece or the sculpt.
You are then going to MOLD your sculpt. Molding is when you are making a negative copy of something, no matter the material it's out of.
Then is the CASTING. This is when you take your negative mold and pour another material inside it, making a copy of your original.

The "pink stuff" is either a silicone or urethane rubber, I'm guessing silicone. I used Rebound 25 because its a brush on silicone. You can use that or mold max 30, but be sure to also get thi-vex which is a silicone thickening agent.
They used playing cards, which is great- I didn't want to risk cutting into my mold and weakening it so I made a clay wall- same exact thing different method.
The "white stuff" you are probably right on the money with it being Smooth cast 300. If you want to use that- then go for it, works perfect. Fiberglass works perfect too. You could even use stone like ultracal (however that starts to get really heavy so opt for one of the other two) It just needs to be a rigid material that will hold the shape so the silicone won't get distorted when you get to the casting part.

From what you wrote my thread is the process you are looking for, just not the materials. My mold is a brush up silicone mold with a two part fiberglass mother mold. I clamped it together by drilling holes and using wing nuts to hold the two fiberglass pieces together.

Hope that helps, and if not that you can find the thread at some point to have it make more sense to you. Hope to see some of your work soon![/QUOTE

First, I'd just like to say, thank you. Your thread and your answers have helped quite a bit... scratch that, they've helped tremendously! And I really appreciate it.
Second, you are correct about the procesess. Being making a mother mold of silicone over the base sculpt and then casting a piece.

So really, I don't know =when= I'll be getting to buy the materials and casting anything (I need to see what's wanted in the market first ;) ) but hopefully it will be soon.



Alaneye said:
Seth, as TessLaeh says, there are lots of ways to approach the moulding and casting of a helmet, and if you succeed in getting a resin copy out of that mould then that method works. I could probably tell you 3 or 4 ways you could do it... and none of them is the 'right'. The method you read about is the method that person used and he could have mixed and matched the techniques from any or all of the ways that I could tell you... the point being, that if you can't find the thread you saw, then all you will get from here is a best guess of what they did... but, right here on the RPF is a method you can see works, and the creator of that thread is right here too speaking to you, so if you have any indepth questions, I'm sure they will be answered.
Click to expand...

I didn't mean any disrespect, all of you here probably don't know how much this means to have someone help me with these questions (IT"S HUGE :) ), so don't take it as dissing anyone, just trying to find the exactly what I would need to buy to get what I want, that's all.

Okay, soooooooooo, For what I'm going to do. I will need...

Smooth on 300 for the mold

Resin/Plastic....

Releasing Agents....

Playing Cards or some other way of separating the molds.

=Seth
Click to expand...
 
No disprespect taken, Seth, I just wasn't sure why you were hanging onto this other method you saw, when there is a working method here.

If you are only pulling a few castings from your mould, a release agent probably isn't necessary, but if you are hoping to get a maximum of pulls then a release agent might let you get a few more at the end of the mould's life. Personally I've never used a release agent with silicone and urethane.

Al
 
It really does depend on how many pulls you want from the mold, each pull - no matter how careful you are in removing it - breakdowns the mold a little at a time ,and depending on how simple or complex your cast. Given you buy an average silicon RTV , you should get on average 20 to 30 pulls from a good set mold, so buy the best platignum casting compound you can afford if you plan on making a few , making only a couple and you do not have to be too fussy. I always, always use a release agent simply because that's want the manufacturer of the casting compound recommends , it's also what the profession says too !!
 
You can also use 'oil bleed' addition cure silicone. Meaning through the life of the mould it will secrete minute amounts of silicone oil creating its own release agent. For that reason it tends to be the most hard wearing and durable of silicones and thus will live through the most amount of pulls.
 
I would call Smooth-On and ask them. I'm sure if you tell them what you need a product to do they will best know what will work best. Good Luck.
 
Alaneye said:
No disprespect taken, Seth, I just wasn't sure why you were hanging onto this other method you saw, when there is a working method here.

If you are only pulling a few castings from your mould, a release agent probably isn't necessary, but if you are hoping to get a maximum of pulls then a release agent might let you get a few more at the end of the mould's life. Personally I've never used a release agent with silicone and urethane.

Al
Click to expand...

I'm going to read over that thread IMENSELY over the next few days. Why is because, I guess of Adam Grumbo's reputation (he founded the 405th, my home forum, so I guess I just naturally took to it as a favorite...). Casting purposes I would want to do either 17 pulls to 30... so probably a release agent a necisary :p

Propsjonnyb said:
It really does depend on how many pulls you want from the mold, each pull - no matter how careful you are in removing it - breakdowns the mold a little at a time ,and depending on how simple or complex your cast. Given you buy an average silicon RTV , you should get on average 20 to 30 pulls from a good set mold, so buy the best platignum casting compound you can afford if you plan on making a few , making only a couple and you do not have to be too fussy. I always, always use a release agent simply because that's want the manufacturer of the casting compound recommends , it's also what the profession says too !!
Click to expand...

Always read directions... Yeah, I agree, I still have all my limbs because of that! XD Seriously, though, sound advice :)

Don Z said:
You can also use 'oil bleed' addition cure silicone. Meaning through the life of the mould it will secrete minute amounts of silicone oil creating its own release agent. For that reason it tends to be the most hard wearing and durable of silicones and thus will live through the most amount of pulls.
Click to expand...

I'm not quite sure about a bleeding silicone... I don't want to leave it somewhere then have it sweat silicone all over the molds resting home :/

v3d said:
I would call Smooth-On and ask them. I'm sure if you tell them what you need a product to do they will best know what will work best. Good Luck.
Click to expand...

I think that will be in order, as soon as I gather just a little more info on what exactly I'll be casting (I need to do some research into helmets that will *cough* sell... that I can make...) and what type of casts I'll make.

-Thanks everybody for more replies :)

-Seth
 
Hi.
if you have enough in your budget! you can use the pour mould method.
it Sounds like this will be your first time molding & casting, so as Bill Murray said once (BABY STEPPING) :rolleyes

Pour molding is more expensive but it will be A stronger & Easier mould to use then Brush-on Moulding if you
have not used mould keys or plaster/resin mother-moulds.

Try a small mould out first and then go on to Your bigger project.. also don't be scared to Try out different materials..
each artist will have there own way to make there mould's.. Some use simple Methods and some use pretty way's with keys and bells on.

if you plan on selling the Finished product you want a strong mould that will not deform after a few cast's.
A decent Silicone pour (Block mould) will be tough enough for many many castings and eliminates under-cut problems.

I would suggest buying a small amount of the materials first and get Familiar with them..
Have Fun :cheers
 
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