Casting with Ecoflex silicone and other questions....

[johnnyhungus]

So I am fairly new to casting in silicone and am having a few hurdles in my results, so am looking for advice or best practice while I am creating my Heath Ledger joker bust.

I am using Ecoflex 30 to cast, and have experimented a little (at great cost) with thickness of skin etc. What kind of thickness do people go for with their skin - 3 or maybe 4 layers? I am slush casting into a dragon skin glove mold. I have tried 3 layers but always seem get problems with the ears being hollow

Once I have the skin, I want to fill the cast with foam but am a little concerned that the foam will "shift" under the skin. I was recommended to try a method of lining the inside of the cast with thin towelling, silicone on one side to adhere, so there could be a mechanical lock with the foam but I am not sure if that is the best way and can create issues with the hair puncher (according to them).

Any pointers would be much appreciated thanks!

 

[udog]

Hi
When you say "slush" you mean you are not brushing it but sort of rotocasting it?
For flexible molds what I do is (this is when molding the head) create a thicker silicone line in the back part of the silicone jacket, from the bottom of the neck to almost the top of the head (you can reinforce that part, where the cut ends with nylon or similar to prevent tearing). Once the mold is finished and before removing the silicone sleeve I cut that back part in a wavy manner (so it´´s clear to me it´s in place when closing it).
This way I can place the silicone mold in the front case and brush the silicone skin in the mold more easily through the open cut I made in the back part. In my last layer I´l close it (with the back part shell) and seal the cut left behind. That also aids to work and reach into the ears.
As for the layers, well, I don´t use Ecoflex (I use it for masks, not for foam filled busts) because as far as I know it can´t be thickened, and even if you could you´d probably loose some of it´s tear strength and stretchiness.I use Dragon Skin 10 for this:
One layer of plain silicone
One layer with a thad of thixo (thickener, Thi Vex), milkshake viscosity.
One layer of thickned silicone (close to mashed potatoes texture, mud).
That makes three layers.
Also I´d go for a rigid two piece mold, no mold release this way.

If your skin layers are thick enough (better for hair punching too) I wouldn´t worry about the foam shifting inside. I can understand the hair puncher not liking the towel as it will be stiffer to work with the needles. Also, again, you will be wasting ecoflex properties by reducing it´s stretchiness to nothing.
To achieve a mechanical grab some people use coton or similar, added to a last fresh silicone layer so the foam grabs in. But sometimes I have experienced teh foam "avoiding " the cotton spot resulting in voids.
With a thick skin and a well pressed foam you should be fine.
Not sure if you have space in your glove mold to use a brush, you could try with a long 45 angle one.
If your only option is slushing in this case, and you can´t go with a thickener I´d go with more layers till you get a good thickness,. And try to insist into the ears as much as possible , maybe you can get a thin brush (cut the stick short enough) in there.
Rotocasting silicone is not that easy, it takes too long to cure.

 

[udog]

Another way of ensuring the ears problem (in your slushing, no thickener case) could be puddling silicone on each ear. I mean, Let your mold rest on one side, pour so it fills the ear, let set, and repeat operation on the other side. Do this in a row right after your first/second layer has just set, to ensure adhesion and prevent delamination.

 

[SkinnedSculpt]

You could fill it with somaFoama from smooth on, its a plat silicone foam so it creates a mechanical lock with the skin without the need for cotton or other linings.

Soma Foama® 25 Product Information


also make sure to use this technique to avoid air pockets

 

[animator]

Okay... I'm a complete amateur with very little silicone experience, so my suggestion is probably terrible, but have you considered making a core for the mold and just gravity pouring the silicone so you can control how thick it is in each area? (Like a silicone pull on mask) I've had excellent success getting Dragon Skin 10 NV to fill in details in a mold with a core.

If you want to have different colored or types of silicone layers, you can brush some on before closing the mold and then pour the rest. I'm using Dragon skin 20 for the tougher or more delicate areas and then Dragon Skin 10 NV for the main backing layer.

Again, I probably have the least experience of anyone here.

I completely understand your frustration with the cost of testing methods with silicone, but I do love the results.

Good luck! Please post the results of your process moving forward.

 

[johnnyhungus]

Hi
When you say "slush" you mean you are not brushing it but sort of rotocasting it?
For flexible molds what I do is (this is when molding the head) create a thicker silicone line in the back part of the silicone jacket, from the bottom of the neck to almost the top of the head (you can reinforce that part, where the cut ends with nylon or similar to prevent tearing). Once the mold is finished and before removing the silicone sleeve I cut that back part in a wavy manner (so it´´s clear to me it´s in place when closing it).
This way I can place the silicone mold in the front case and brush the silicone skin in the mold more easily through the open cut I made in the back part. In my last layer I´l close it (with the back part shell) and seal the cut left behind. That also aids to work and reach into the ears.
As for the layers, well, I don´t use Ecoflex (I use it for masks, not for foam filled busts) because as far as I know it can´t be thickened, and even if you could you´d probably loose some of it´s tear strength and stretchiness.I use Dragon Skin 10 for this:
One layer of plain silicone
One layer with a thad of thixo (thickener, Thi Vex), milkshake viscosity.
One layer of thickned silicone (close to mashed potatoes texture, mud).
That makes three layers.
Also I´d go for a rigid two piece mold, no mold release this way.

If your skin layers are thick enough (better for hair punching too) I wouldn´t worry about the foam shifting inside. I can understand the hair puncher not liking the towel as it will be stiffer to work with the needles. Also, again, you will be wasting ecoflex properties by reducing it´s stretchiness to nothing.
To achieve a mechanical grab some people use coton or similar, added to a last fresh silicone layer so the foam grabs in. But sometimes I have experienced teh foam "avoiding " the cotton spot resulting in voids.
With a thick skin and a well pressed foam you should be fine.
Not sure if you have space in your glove mold to use a brush, you could try with a long 45 angle one.
If your only option is slushing in this case, and you can´t go with a thickener I´d go with more layers till you get a good thickness,. And try to insist into the ears as much as possible , maybe you can get a thin brush (cut the stick short enough) in there.
Rotocasting silicone is not that easy, it takes too long to cure.

Thank you for a great detailed answer, it is much appreciated.

Yes, I am kind of rotocasting the the silicone around the inside of the mold. It is pretty tricky to get my hand inside the neck area (it's a head bust) and it doesn't help that I have giant hands! I am going to try to cut a brush handle down and attempt to brush on the layers, see how that goes.

The UK supplier of Smooth-On products recommended Ecoflex 20 for the bust as it has a very "human skin" like feel to it, which seems to be true, it does feel great when cured but is a total pain to trim around the eyes. I have been fairly lucky with my tests - 4 heads so far and hoping the 5th one comes good - I have had minimal bubbles but need to perfect the process. The glove part of my mold is made of Dragon Skin 10 NV, would I be able to cast Dragon Skin into this again? I guess I would as it is just silicone. I am on my 3rd mold too because the release agent they supplied (Ease Release 205) did not release properly at all and after much discussion, I have found the perfect release agent, 2 parts IPA to 1 part washing up liquid is PERFECT! I may try Dragon Skin with this at some point but I have a gallon of Ecoflex to use now...

I didn't like the towelling method of forming a mechanical lock between the foam and silicone on the inside, it was quite apparent when handling the head and if you looked closely, I think you could make out some undulation. I have nbeen using Thi-Vex for thickening up the Ecoflex too, with no issues as yet (fingers crossed).

I may do a couple of think layers and try the puddling method you mention, that could work. I am going to go for another cast at the weekend, thanks for your advice!

 

[johnnyhungus]

You could fill it with somaFoama from smooth on, its a plat silicone foam so it creates a mechanical lock with the skin without the need for cotton or other linings.

Soma Foama® 25 Product Information


also make sure to use this technique to avoid air pockets

This looks like an option, not sure why it wasn't recommended to me by the supplier. I am using FlexFoam-It X, so will have a chat with them about this, thanks.

Had a quick chat and had to pick myself up off the floor when they told me the price, I think I may have to stick with the stuff I have got for now!

 

[johnnyhungus]

Okay... I'm a complete amateur with very little silicone experience, so my suggestion is probably terrible, but have you considered making a core for the mold and just gravity pouring the silicone so you can control how thick it is in each area? (Like a silicone pull on mask) I've had excellent success getting Dragon Skin 10 NV to fill in details in a mold with a core.

If you want to have different colored or types of silicone layers, you can brush some on before closing the mold and then pour the rest. I'm using Dragon skin 20 for the tougher or more delicate areas and then Dragon Skin 10 NV for the main backing layer.

Again, I probably have the least experience of anyone here.

I completely understand your frustration with the cost of testing methods with silicone, but I do love the results.

Good luck! Please post the results of your process moving forward.

I am trying hard to visualise that but my head is having trouble! What kind of stuff are you casting?

As for results so far, well, I have some badly cast heads I am messing around with...

 

[udog]

Ecoflex 20 for the bust as it has a very "human skin" like feel to it,

True, but does a display piece need the "feel"?. Will it be touched?.
What I mean is that each application has it´s materials. Ecoflex is a soft and very stretchy silicone, good for masks and others that need to have the "feel". But in appearance its clear silicone, the same as DGSK10 or others. So as for colors, and skin appearance its the same thing but more expensive.
Actually if it´s a foam filled piece when you press the head with your hand it will squish, heads don´t do that. The feel probably would be more realistic with a rigid core inside (pour method, mentioned above and described below)
Soma Foama is a very interesting one, will create chemical adhesion. But expensive, heavier and maybe too soft for a head. Great material anyway, if you try it take in account it starts growing pretty fast (specially in hot summer) and the expansion is very strong, so if in a closed mold, or pressed, make sure your mold flanges are strong enough. I´ve seen it crack fiberglass mold flanges (totally closed molds).
And the pour method mentioned above could be a good one for ecoflex, the only thing is that you´d have to remove the core to pour foam in, and that could be risky. But you could consider creating a fiberglass (or similar) core that stayed in as part of the piece, substituting the foam. A permanent core. That would mean another mold for the core.

 

[udog]

Nice work by the way.

 

[johnnyhungus]

Nice work by the way.

Thank you!

I understand what you mean about the type of silicone needed for a bust and think I am going to give Dragon Skin a go, I have a couple of trial packs here, so could use them for the beauty layer and until I run out, then consider what to do after that. I am thinking of the core idea, it could be a goer if I can figure out a simple-ish way to do it.

 

[udog]

I am thinking of the core idea,

The thing is that with your glove mold it might be very complicated. The best way would need remolding, don´t know if that¨s possible , in a two part rigid mold.
If you want the head to be have a harder feel you could always fill it wit rigid foam(FoamIt for example).

 

[animator]

I am trying hard to visualise that but my head is having trouble! What kind of stuff are you casting?

As for results so far, well, I have some badly cast heads I am messing around with...

View attachment 1005961 View attachment 1005962 View attachment 1005963 View attachment 1005964

I have a thread here called "T_Rex Sculpt for puppet WIP" that is documenting the process I am trying -again this might be a terrible idea for you. This is my first attempt with silicone.

I used a thin layer of clay in my mold to define where and how thick I wanted the silicone to be, then I rotocast a core with Task 15 (filled that with foam). You can then remove the clay from the mold, put the core into the mold and pour the silicone into the void between the mold and the core, so you are essentially casting a silicone skin.

I am first painting print layers of different colors of silicone in the mold to give the color some depth, then inserting the core and pouring in the main silicone.

I am just staring the learn the process. The other people giving you suggestions are all much more knowledgeable. What I am doing is closer to how people make pull-over silicone masks, but they would usually start with a core and sculpt on it.

Again, good luck! You sculpture looks great!

 

[johnnyhungus]

The thing is that with your glove mold it might be very complicated. The best way would need remolding, don´t know if that¨s possible , in a two part rigid mold.
If you want the head to be have a harder feel you could always fill it wit rigid foam(FoamIt for example).

I am going to try a few different approaches first, maybe 3 or 4 layers of silicone first, fill the nose chin and ears, another layer of silicone (thick) and then some discreetly placed squares of towel for a mechanical grab to the foam.

If that doesn't work, I will look at making a new mold.

 

[johnnyhungus]

I have a thread here called "T_Rex Sculpt for puppet WIP" that is documenting the process I am trying -again this might be a terrible idea for you. This is my first attempt with silicone.

I used a thin layer of clay in my mold to define where and how thick I wanted the silicone to be, then I rotocast a core with Task 15 (filled that with foam). You can then remove the clay from the mold, put the core into the mold and pour the silicone into the void between the mold and the core, so you are essentially casting a silicone skin.

I am first painting print layers of different colors of silicone in the mold to give the color some depth, then inserting the core and pouring in the main silicone.

I am just staring the learn the process. The other people giving you suggestions are all much more knowledgeable. What I am doing is closer to how people make pull-over silicone masks, but they would usually start with a core and sculpt on it.

Again, good luck! You sculpture looks great!

Thanks, it's a huge learning curve but worth it! I will check out your thread

 

[dharma]

I haven’t read all the post deeply but I never would use a so soft silicone in abust n order to long lasting and punching. Try to use dragon skin 20 or transil20. Thexollector will be much more happy in a future

 

[animator]

I haven’t read all the post deeply but I never would use a so soft silicone in abust n order to long lasting and punching. Try to use dragon skin 20 or transil20. Thexollector will be much more happy in a future

Hi dharma -can you explain why you would use a 20 instead of a 10 or softer silicone so we can learn. Does the softer silicone not last as long, or sag over time or deform more when you punch hair in it? You do amazing work!

 

[johnnyhungus]

I haven’t read all the post deeply but I never would use a so soft silicone in abust n order to long lasting and punching. Try to use dragon skin 20 or transil20. Thexollector will be much more happy in a future

As animator says, is there any reason you would not use something like Ecoflex 30? Although it is quite soft, it looks amazing and very skin like. I didn't get to try my trial Dragon Skin 10 but i will, as this bust is for my own personal display, unless there is a major reason for not using the Ecoflex, then I will pursue a good result - plus I have a gallon of it left to use!

I pooled the silicone for the ears as udog suggested and this works great, thanks for the tip! Though I used a brush for the first layer and it seemed to create some issues with the mold release and subsequently caused some release issues with the cast.

The thing I am curious about is how thick your layers are - what kind of thickness should I go for? 1/4 inch? 1/2 inch?

 

[dharma]

I agree with you about the good and soft surface it is. But more oil in the mix(the oil/slacker make the silicone softer ) make the silicone les durable in time. For a very long lasting is better harder silcone. If you don’t need a long lasting piece eco flex is perfect.
In other hand for punching pursuits a harder silicone is better looking because the hole of the needle is almost invisible.
Just only my experience and preference. Good luck on the bust.

 

[birddog316]

I am also having a small bit of brain trauma over this LOL...i understand the concept of a 2 part mold...foaming the face and back seperatly....then what is a good adhesive to put the two together to make a core?....and is there a way possible to get the foam to "shrink" a little as the one inch clay layer between the foam core and the mothermold negative seems to be a bit too thick for the silicone to set into....maybe I am looking at this too logistically? Seems the head itself would be a bit bigger than normal? Also is 10NV a good silicone to use for things like masks/head props?