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Mr Justin Profile
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Silocone/Fiberglass Molds, a question:


Hey, I was looking on Smooth-on's website and was wondering what kind of silicone should I use to cast Urethane in? I'm really new to molding in general and don't know where to start when it comes to doing silicone molds. Any advice is greatly appreciated. Thanks guys!

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7/13/2009, 3:02 pm Link to this post Send Email to Mr Justin   Send PM to Mr Justin
 
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Re: Silocone/Fiberglass Molds, a question:


well you can use any silicon from smoth one to cast urethane but it all depends what you are molding
there is pourable silicon and there is brush able
and there is tin cure or platinum silicon

so let me know what you will be molding and i will
help you out


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resinsamurai Profile
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Re: Silocone/Fiberglass Molds, a question:


Start with:


 What are you looking to mold?

 Do you want soft or hard urethane pulls from the mold
when you are finished.


That will give a general direction of what you will need to
use to mold it.

---
And what’s ten years? Well, it’s roughly how long it takes to put in ten thousand hours of hard practice. Ten thousand hours is the magic number of greatness.
7/13/2009, 9:21 pm Link to this post Send Email to resinsamurai   Send PM to resinsamurai
 
Mr Justin Profile
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Re: Silocone/Fiberglass Molds, a question:


  Sorry guys, I should've been more specific. I'm planning on molding a cowl sculpt I've been working on, and casting the cowl in a 40 Shore Urethane. I've read about how it's done and seen pictures, but I'm pretty much cluless when it comes to the actual process.

  My only molding experiance is with Ultra-cal gypsum cement used to cast latex pieces.

  Another thing I'm not sure of is constucting the silicone mold. Do people typically do a one piece silicone mold, or is it more practical/better to do a two piece mold with a dividing wall down the sides of the cowl?
  I've always thought it was better to cover the whole cowl in silicone, and then when castings are done, "unwrap" the silicone off of the Urethane. Or is that not how it's done? lol...You can see how inexperianced I am with this! Just want to make sure I do it right if I invest the money in the materials for running a urethane cowl. emoticon

Last edited by Mr Justin, 7/13/2009, 10:45 pm


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7/13/2009, 10:41 pm Link to this post Send Email to Mr Justin   Send PM to Mr Justin
 
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Re: Silocone/Fiberglass Molds, a question:


email me and i will send you my # and i can talk you threw it

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Re: Silocone/Fiberglass Molds, a question:


Can we see a pic of the sculpt?

Couple RuleS!!

1. Make sure you paint the entire sculpt with a low sheen black primer. This is to ensure a uniform finish and it will seal the sculpt against the silicone. Silicone picks up the finest and ever more finest LOL of details. So make 100 percent sure your sculpt is finished, clean, and ready for molding. Primering the sculpt may reveal things you missed seeing. Don't be afraid to stop, fix things, then reprimer and then mold.

NO SHORTCUTS!!


2. Your release will make a huuuuuuuuuuuuuuuge difference in the quality of the finish of your piece. SO you will need to select a finish that will compliment the piece. For a cowl, one of the best is low sheen rocket release. you just want to make sure to use the finest bristle brush possible as you brush thru the first and second coats.


..........................

One piece molds are the best thing possible when doing a full head one piece mask. So yes you will want to coat the entire sculpt with 5 to 10 thin coats of silicone. You will want to use either V-1065 silicone or something like moldmax 30. Both are low shore High tear strength. In short, hard to destroy since the demolding process is very very very strenuous on both the sculpt, the mold, and you.


So, short version.

Put many layers of thin silicone (thinner the better so no air is trapped, even after you degas the silicone you still can end up moving and traping air as you skin the sculpt) when the silicone is done, then use hot glue or molding wax to hold up a mold wall made of playing cards. Playing cards work awesome because they are pre-waxed and take little release to ensure they don't take on resin from the jacket.

Draw a line on the silicone with a black sharpe, run your glue a little bit at a time, plant the card, glue them to each other. Release both sides of the card heavily to make sure resin doesn't soak in between them and glue the halfs of the mold together

You'll want to put the half line in front of the ears as long as the ears aren't a locking point in the mold.

The back half of the mold holds the ears, the front half holds the face ... and so on. 60/40 split usually.

So, silicone, then back jacket, front jacket.

then de-jacket, de-silicone, then re-jacket and let the mold stand in the jacket for at least 48-96 hours prior to running the first drop of urethane into the mold. This gives the mold time to cure, degas, and tighten up both in whole and on the skin. You will get a better mold life because of this critical and most often missed move.

there are 100 little steps in between there that would take a long time to detail out so hopefully one of the others will help you with that. I have just given you some of the key basics.
 

---
And what’s ten years? Well, it’s roughly how long it takes to put in ten thousand hours of hard practice. Ten thousand hours is the magic number of greatness.
7/14/2009, 2:27 am Link to this post Send Email to resinsamurai   Send PM to resinsamurai
 
Mr Justin Profile
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Re: Silocone/Fiberglass Molds, a question:


quote:

resinsamurai wrote:

Can we see a pic of the sculpt?

Couple RuleS!!

1. Make sure you paint the entire sculpt with a low sheen black primer. This is to ensure a uniform finish and it will seal the sculpt against the silicone. Silicone picks up the finest and ever more finest LOL of details. So make 100 percent sure your sculpt is finished, clean, and ready for molding. Primering the sculpt may reveal things you missed seeing. Don't be afraid to stop, fix things, then reprimer and then mold.

NO SHORTCUTS!!


2. Your release will make a huuuuuuuuuuuuuuuge difference in the quality of the finish of your piece. SO you will need to select a finish that will compliment the piece. For a cowl, one of the best is low sheen rocket release. you just want to make sure to use the finest bristle brush possible as you brush thru the first and second coats.


..........................

One piece molds are the best thing possible when doing a full head one piece mask. So yes you will want to coat the entire sculpt with 5 to 10 thin coats of silicone. You will want to use either V-1065 silicone or something like moldmax 30. Both are low shore High tear strength. In short, hard to destroy since the demolding process is very very very strenuous on both the sculpt, the mold, and you.


So, short version.

Put many layers of thin silicone (thinner the better so no air is trapped, even after you degas the silicone you still can end up moving and traping air as you skin the sculpt) when the silicone is done, then use hot glue or molding wax to hold up a mold wall made of playing cards. Playing cards work awesome because they are pre-waxed and take little release to ensure they don't take on resin from the jacket.

Draw a line on the silicone with a black sharpe, run your glue a little bit at a time, plant the card, glue them to each other. Release both sides of the card heavily to make sure resin doesn't soak in between them and glue the halfs of the mold together

You'll want to put the half line in front of the ears as long as the ears aren't a locking point in the mold.

The back half of the mold holds the ears, the front half holds the face ... and so on. 60/40 split usually.

So, silicone, then back jacket, front jacket.

then de-jacket, de-silicone, then re-jacket and let the mold stand in the jacket for at least 48-96 hours prior to running the first drop of urethane into the mold. This gives the mold time to cure, degas, and tighten up both in whole and on the skin. You will get a better mold life because of this critical and most often missed move.

there are 100 little steps in between there that would take a long time to detail out so hopefully one of the others will help you with that. I have just given you some of the key basics.
 



Wow! Thanks man. Two questions though, can you elaborate on the terms "release" and "degas"? other than that it makes perfect sense to me.

Here's the most recent pics of my sculpt (Still not finished). The thing is, I'm using water based clay... emoticon and even though I try to keep it moist and cover it up when I'm done, it's starting to dry out. I took the plastic bag off of it yesterday to work on it, and there were fissure lines and cracks running across the nose and other parts of the face/sides. I fixed and smoothed them as best as I could, but I'm still not done with that even... Anyway, here's some recent pics:

Image

Image

Image

Now here's a few that are a little blurry, but without the flash to show more shadow on it.

Image

Image

Image

Thanks again guys, this is my very first cowl sculpt (Shocker, right?... emoticon lol). and after owning one of Jeff's great Urethane cowls, I knew that I'd want to run my own in Urethane as well.

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7/14/2009, 9:24 am Link to this post Send Email to Mr Justin   Send PM to Mr Justin
 
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Re: Silocone/Fiberglass Molds, a question:


Theres some outstanding info there! Ill be stealing some of it when molding mine.
Can I add a question, like you said, the primer may show some areas that still need work, how do you remove it without taking chinks of clay out? Mineral spirits?

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7/14/2009, 10:33 am Link to this post Send Email to TheKingaSwing   Send PM to TheKingaSwing Yahoo
 
resinsamurai Profile
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Re: Silocone/Fiberglass Molds, a question:


#1 When ever you have a question, look it up before asking. That is a huuuuuuuuge pet peeve of mine. The internet is a vast vast vast ocean of information that is available at the click of your finger. So always look thru google, you tube, and other threads here to see what info is available.

Not being a jerk, just trying to teach you to fish instead of giving you a fish to eat. Right this second versus a lifetime kinda things.

SO........
Google : Urethane Rocket Release
Google : Silicone Vacuum Degas

Before you attempt anything I would suggesting
watching every video here to get the gist of things.

http://www.freemansupply.com/video.htm

nothing is a substitute for an education prior to trying
you have to try in order to make sense of what your reading up on but you have do both to succeed



as for the second question, you don't remove the primer. You fix the sculpt and then primer that area again or you re primer the entire thing, primer is a whisper thin layer so it will move and fold into the clay easily.

hopefully your not using super soft clay for this kind of work, stiff to hard clay is needed when your working on mechanical style pieces that have a lot of symmetry.

Soft clay is perfect for organic pieces.

Proper tools/media for the proper job or sculpt in this case.



I have to ask, because I would really like to here the answer, is why you chose to sculpt a cowl that is so readily available in multiple sizes and media?

The sculpt looks to be coming along well, but you will need to tighten a few things up either before you mold it or by bodyshoping a resin casting, which is usually the best way. Also, it looks like one cheak is more dense then the other by the look of it sitting on Joe there.

Because Joe is a perfectly symmetrical armature you have a unique opportunity to sculpt your piece very symmetrical as well. That's not normally possible in a real life cast because to humans face is symmetrical... just sometimes pretty close. So its a great thing to start learning on. And if you never do anything like a prosthetic you will never need to worry about it~

another trick to help you see things in the sculpt that you might miss is look at the sculpt in a mirror. Because it reverses the entire piece in your mind, you will look at it differently now because of that... even if you have been staring at it all day regularly... your mind will see it differently when you look at it thru a mirror reflection

just a neat trick when your brain is turning to mush over the details in a sculpt


anyways, gotta run!

---
And what’s ten years? Well, it’s roughly how long it takes to put in ten thousand hours of hard practice. Ten thousand hours is the magic number of greatness.
7/14/2009, 9:23 pm Link to this post Send Email to resinsamurai   Send PM to resinsamurai
 
Mr Justin Profile
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Re: Silocone/Fiberglass Molds, a question:


Thanks! Yeah, I try to do as much research on my own, but even when I'm looking at some things, I'm still not sure if it's what I should be looking at. Thanks for pointing me in the right direction though.

I chose this cowl as my first sculpt just so I could get a feel for what it's like to sculpt a cowl. I wanted to do something that I could have tons of reference pics to look at while doing it. I guess you could almost call this a "practice run" type of thing lol. Another reason is that I feel better about making whatever piece I can instead of trading with someone else. If I had the skill,time, and resources to build an entire suit, I'd do it in a heartbeat. I have the desire to do it, but I don't have the ability to, yet.

You're absolutely right about the current look of the cowl. The cheeks are driving me a little nuts. The right side (facing us in the pic) is the "unfinished" side. I still need to make the lower portion below the line more concave on both sides; and I need to smooth, thin and nit-pick the hell out of the right side. The top portion also needs smoothing near the base of the ears.

Again though, thanks for all your advice! This is such an in-depth process, and it's so involved I really wanted to have a hold on the process of it all before I invested the money and effort into it. I'm going to watch those vids and look up those terms.

The next cowl I want to sculpt is going to be, without a doubt, a Tim Sale cowl from "The Long Halloween". I can't wait to start that!

Last edited by Mr Justin, 7/14/2009, 9:40 pm


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