Fibreglass, jesmonite or plaster mould for mask sculpt

[Jayesh Ranavaya]

Hey guys. I have been going crazy trying to figure out which one of these materials to use for my mould. I am redoing my Freddy Part 2 sculpture as I was not happy with the silicone mask I pulled from my first attempt. So now I am taking my time and getting the sculpt as close to the real thing as possible. You can check out my sculpt/mask thread here: http://www.therpf.com/f62/freddy-kruger-part-2-revenge-sculpt-wip-first-ever-sculpt-attempt-192644/

I have made plaster of paris moulds before but they have been faar too weak. I have been told by MANY professionals that fibreglass is the ONLY way to go to get a good mould created for a full head sculpt.

Interestingly I have been advised also that jesmonite is a good material which applies like plaster but is a HELL of a lot stronger.

I have also heard of polyurethane rubber or even silicone inner moulds, with plaster/fibreglass/jesmonite outer moulds too. I hear this gives the LEAST seams with only one at the back which is barely visible? Only problem would be a risk of not using enough release agent with a silicone inner mould and the silicone cast getting stuck permanently! haha

I just wanted some pro's and cons really and your views on this.

I am in the UK if that helps

Cheers guys.

 

[Mr Mold Maker]

What I always consider when doing a mould is;
Budget,
Time,
and Weight.

Jesmonite is cheap for most budgets, and fairly quick to mould with, but the weight is going to be very heavy. A full size head sculpture may be in excess of 15-20 pounds. (Going off of UltraCal as a comparison) Gypsums also deteriorate with use.

Fiberglass is very light weight, and is reasonably within most budgets but it takes a lot of time and care to mould with. You also have to be very precise when mixing most resins. I always use a scale. Fiberglass moulding in my eyes is almost an art form in itself and it takes time and experience to get it right. Fiberglass holds detail a lot longer than most gypsum moulds, as well.

Silicone in a matrix mould is what I personally prefer. It is fairly light weight depending on what you use as your mother mould, and with experience can be done in a day or two depending on the curing time of the rubber you use. It is very costly however. Silicone most of the time doesn't come cheap. Urethanes are less expensive, and may work but you'd need to make sure it wouldn't inhibit the silicones cure. Also, mould release is a must, as you don't want the mould and the piece stuck together.
A silicone mould pulling only silicone pieces will last for a very, very long time.
I believe most silicone mask companies actually use a silicone matrix mould with a fiberglass mother mould.

- - - Updated - - -

Bonus Fact! Plaster of Paris is known as "soft plaster" and is terrible for almost all mould making situations.

You can however add one part Portland Cement for every two parts Plaster of Paris you have and make your own UltraCal.

 

[Canobi]

The latter is indeed the best way to go for detaild casts, and a combo of fibreglass matt and jasmonite will make a very strong jacket mould that isn't smelly or toxic. A bit of vasaline on cured resin is a great release agent and goes along way :thumbsup

 

[Jayesh Ranavaya]

Great so what type of silicone would be best to use for the inner mould? Also with it being silicone I would be terrified that it would stick so how would I ensure the silicone cast doesn't stick to the silicone mould?

I have never worked in fibreglass and also don't have the space for it or proper ventilation as it is a room in my flat so want to stay away from it if possible. Weight isn't a problem at all so don't mind working in a strong plaster. I have heard this Basic Alpha plaster is VERY strong Tiranti - Product Details - Basic Alpha Plaster 25kg

any thoughts? Just want the best option where the mould wouldn't deteriorate.

Also on another note, if I used a polyurethane rubber or silicone inner mould that would allow me to cast hard materials for busts etc. This is something I am really interested in doing too so may be the way to go.

thanks for the advice so far.

 

[Jayesh Ranavaya]

Also looking at these videos of James from Darkride studios, what do you think he used for his mould? Fibreglass maybe as it's very thin?

Torched mold - YouTube
Freddy vs James - YouTube

 

[Canobi]

I'd use condensation cure RTV silicone as it's much less expensive than its addition/platinum cure cousin. As you're mask making, I'd get one of the stiffer types, around a shore 45A or higher for rigidity (the shore rating is all about how much strech/bounce the silicone/resin has. The higher the number, the stiffer it is). Concrete casting silicone would probably work best in this case (IIRC I think its about a shure 75A).

Technically, if your casting silicone, you want a solid mould really. If your not keen on plaster, then jasmonite is a good bet. Jasmonite is a water soluble, odorless and non toxic resin (no stinky flat) that has very low shrinkage on curing. Used together with fibreglass matting (Not to be confused with fibreglass resin that is very toxic and fumey. The matting has no smell, but do wear a mask, gloves and long sleeves) will make a very tough mould shell.

As for a good release agent (especially silicone/silicone combo's), my favorite tried and true is a cheep homemade release. First get a misting spray bottle (for misting flowers) fill to about an inch from the top with white spirits and drop in two good teaspoons of vaseline and mix/stir till its dissolved :thumbsup

The white spirits acts as the suspension fluid and will evaporate leaving a very fine layer of vasaline behind. If you need to be a little more detailed with the release agent just paint it on with a fine paintbrush, it'll self level before evaporating so no hair/stroke marks are left behind.

 

[Jayesh Ranavaya]

I'd use condensation cure RTV silicone as it's much less expensive than its addition/platinum cure cousin. As you're mask making, I'd get one of the stiffer types, around a shore 45A or higher for rigidity (the shore rating is all about how much strech/bounce the silicone/resin has. The higher the number, the stiffer it is). Concrete casting silicone would probably work best in this case (IIRC I think its about a shure 75A).

Technically, if your casting silicone, you want a solid mould really. If your not keen on plaster, then jasmonite is a good bet. Jasmonite is a water soluble, odorless and non toxic resin (no stinky flat) that has very low shrinkage on curing. Used together with fibreglass matting (Not to be confused with fibreglass resin that is very toxic and fumey. The matting has no smell, but do wear a mask, gloves and long sleeves) will make a very tough mould shell.

As for a good release agent (especially silicone/silicone combo's), my favorite tried and true is a cheep homemade release. First get a misting spray bottle (for misting flowers) fill to about an inch from the top with white spirits and drop in two good teaspoons of vaseline and mix/stir till its dissolved :thumbsup

The white spirits acts as the suspension fluid and will evaporate leaving a very fine layer of vasaline behind. If you need to be a little more detailed with the release agent just paint it on with a fine paintbrush, it'll self level before evaporating so no hair/stroke marks are left behind.

Great thanks wouldn't that condensation cure silicone inhibit the cure of the platinum silicone though?

I;ve seen one on mouldlife's website TinSil 8030 but i think this will be too soft and i have heard the platsil gel-00 silicone won't sure..

Hmm...I originally was thinking jesmonite as it is supposed to be super strong and lighter than plaster. I may just go with this.

 

[clonesix]

Hi Jayesh, Welcome to the forum, and that is some beautiful work on the sculpt.


General Rule of Mold Making: Hard part; Soft tool. Soft part; Hard tool

Meaning: If you want to cast your mask in a soft material like Silicone RTV, or Latex, then you want a hard mold material, like Gypsum, of fiberglass. If you are going to cast a hard part in resin, then you need a soft mold material, like RTV.

Since you want to cast your Freddie in Silicone, I recommend Fiberglass for the mold (mould). It is pricier than gysum, but lightness and durability make up for the added cost. One point of note: It appears to me from the video that you did not use a life cast to model onto, and that there is a "newspaper/tape" armature supporting the sculpt. Is this right??

I ask because if it IS a paper wad being used as an armature, then it cannot be used as the mold core. If you are going to pour silicone into the mold, then you need a solid core to make it hollow.

If you wish to cast the mask in Latex, then either Fiberglass or Gypsum would work. If Gypsum, then Plaster of Paris is the WORST possible material, and you need to step up to Hydrocal, or other stronger Gysum product available in the UK. The pourous nature of the gypsum allows the latex to be poured in, and poured out, to leave you with a hollow mask. The NON-pourous nature if fiberglass, requires that you brush in several small coats of latex to get your results.

Hope that helps

 

[Canobi]

My bafacepalm), your right the condensation cure will inhibit the platinum silicone.

The tensil 8030 is a bit soft at shore A30, but you could make the silicone mould quite thin so the hard shell does all the work to keep it firm and in shape, and since the casting is hollow, and rubber, there's no risk of tearing like there would be with a solid resin cast.

I would definitely look into using fibreglass matting with the jasmonite, it will make the jasmonite go much further, and improve the longevity of the jacket mould. One tip for the matting, chopped strand for detailed or intricate shapes as its much better at conforming and shaping, top weave for wide flatish areas or as a final layer for smoothing the mould jacket surface, though its not essential.

 

[Jayesh Ranavaya]

Hi Jayesh, Welcome to the forum, and that is some beautiful work on the sculpt.


General Rule of Mold Making: Hard part; Soft tool. Soft part; Hard tool

Meaning: If you want to cast your mask in a soft material like Silicone RTV, or Latex, then you want a hard mold material, like Gypsum, of fiberglass. If you are going to cast a hard part in resin, then you need a soft mold material, like RTV.

Since you want to cast your Freddie in Silicone, I recommend Fiberglass for the mold (mould). It is pricier than gysum, but lightness and durability make up for the added cost. One point of note: It appears to me from the video that you did not use a life cast to model onto, and that there is a "newspaper/tape" armature supporting the sculpt. Is this right??

I ask because if it IS a paper wad being used as an armature, then it cannot be used as the mold core. If you are going to pour silicone into the mold, then you need a solid core to make it hollow.

If you wish to cast the mask in Latex, then either Fiberglass or Gypsum would work. If Gypsum, then Plaster of Paris is the WORST possible material, and you need to step up to Hydrocal, or other stronger Gysum product available in the UK. The pourous nature of the gypsum allows the latex to be poured in, and poured out, to leave you with a hollow mask. The NON-pourous nature if fiberglass, requires that you brush in several small coats of latex to get your results.

Hope that helps

Hey thanks for the informative post. There is a lifecast under the sculpt, it is black coloured. It's just that it doesn't have shoulders so I added a temporary newspaper and tape fix to allow me to push the sculpt out further. I intend to reinforce this with something harder which will stay put so it can be used for injection casting.

 

[Beaker]

If you use Fiberglass be very aware that fresh styrene (the 'smell' of polyester resin) will inhibit platinum silicone... when the smell is gone, generally it is ok to use at that point....
Most of my guys in Hollywood are starting to use the EpoxAcoat along with the Free Form Air to make a very rigid, very light weight silicone mold that will last a million years I do believe..lol
Two layers of the EpoxAcoat over the original then a 3/8" layer of Free Form Air syntactic dough over the EpoxAcoat... super strong and even floats it's so light....
EpoxAcoat® Surface Coat Epoxies
Free Form® Air Epoxy Putty - lightweight tooling and laminating epoxy

 

[Jayesh Ranavaya]

My bad palmface), your right the condensation cure will inhibit the platinum silicone.

The tensil 8030 is a bit soft at shore A30, but you could make the silicone mould quite thin so the hard shell does all the work to keep it firm and in shape, and since the casting is hollow, and rubber, there's no risk of tearing like there would be with a solid resin cast.

I would definitely look into using fibreglass matting with the jasmonite, it will make the jasmonite go much further, and improve the longevity of the jacket mould. One tip for the matting, chopped strand for detailed or intricate shapes as its much better at conforming and shaping, top weave for wide flatish areas or as a final layer for smoothing the mould jacket surface, though its not essential.

Hey. Great what if I used fibre tissue for the little surface details? would that work? I somehow in my mind think chopped strand would be too thick and simply wouldn't be able to get into those little holes and details. And then on the second to fourth coat use chopped strand matting.

Also would jesmonite deteriorate over time? I'm thinking fibreglass just to ensure the mould lasts longer as mentioned above it costs a bit more but you get that back with the amount of time it lasts.

 

[Canobi]

Moulds that float?!, now that sounds cool, hand rotocasting would benifit from moulds like that no end :lol

Thanks for sharing that one

If you use Fiberglass be very aware that fresh styrene (the 'smell' of polyester resin) will inhibit platinum silicone... when the smell is gone, generally it is ok to use at that point....
Most of my guys in Hollywood are starting to use the EpoxAcoat along with the Free Form Air to make a very rigid, very light weight silicone mold that will last a million years I do believe..lol
Two layers of the EpoxAcoat over the original then a 3/8" layer of Free Form Air syntactic dough over the EpoxAcoat... super strong and even floats it's so light....
EpoxAcoat® Surface Coat Epoxies
Free Form® Air Epoxy Putty - lightweight tooling and laminating epoxy

 

[Mr Mold Maker]

What if I used fibre tissue for the little surface details? would that work? I somehow in my mind think chopped strand would be too thick and simply wouldn't be able to get into those little holes and details.

I believe in most mould making situation you'd use the Jesmonite for a thin detail coat while it's still a bit of a soup consistency.

The Fiberglass mat is just for added strength, and is added on the 3rd and 4th layer generally.
You could also use something like Burlap. I add burlap to all of my UltraCal moulds and I'll be honest... I'm a "dropper."
Burlap has saved moulds from being cracked numerous times from drops to the ground.




I'd say using a fiberglass tissue (Insulation?) as your detail layer would be a big no. If the material isn't saturated enough it could poke through the Jesmonite and silicone could become entrapped in it.

I can't say for sure as my experience with Fiberglass Insulation ends at some mixed into latex for Leatherface masks.

I can say it absorbs a good amount of liquid, and when dry tends to be brittle even with the latex mixed into it. Plus it's very itchy if you're not careful. Unless it is for a special look like dried skin, I'd recommend staying as far away from fiberglass insulation as possible.

 

[Jayesh Ranavaya]

Also looking at these videos of James from Darkride studios, what do you think he used for his mould? Fibreglass maybe as it's very thin?

http://www.youtube.com/watch?v=MNIJo58ITI8
http://www.youtube.com/watch?v=lDZZ-XHyhBM