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  1. BigMarv's Avatar
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    May 4, 2006, 8:19 AM - What's the best value silicone for BIG Mold Making? #1

    Currently sculpting a large freestanding Marvin the Martian with numerous weak points and undercuts.

    Been advised that fibreglass cast from silcone mold with outer fibreglass jacket is the way to go.

    Considering the size of the model (over 3ft tall) and the fact that I'll only want 1 or 2 copies, what's the cheapest stuff that will do the job?

    Many thanks in advance

    Paul.
  2. fettpride's Avatar
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    May 4, 2006, 6:18 PM - Re: What's the best value silicone for BIG Mold Making? #2

    Smoothon.com. Mold Max™. THey have different hardness to choose from. Tin cure, pretty decent life, cheap.
    1 Gallon Unit is about $85. If you're not comfortable with the 10:1 mix, then try the following ...

    Smooth-On just introduced an "Economy" grade Tin Cure silicone that is DIRT cheap. It's made for the purpose that you mentioned ... one off's ect. Good for probably 2 polyester pulls. Designed for rapid prototyping. Can't remember the name ... but if you give them a ring, they'll tell you, probably without you having to ask.

    BUT, if there are that many undercuts, and it's 3 ft tall,you will want some elasticity and vertical brush-ability .. you should consider their Rebound™ product. Platinum cure (addition cure), offered in a 25 shore hardness, vertical abilities, ect, ect. A bit more expensive, but WORTH it. Easy 1:1 mix ratio. The problem is, you're mold will be around for a while

    FP
    Last edited by fettpride; May 4, 2006 at 7:24 PM.
  3. MARROW SUN's Avatar
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    May 4, 2006, 6:35 PM - Re: What's the best value silicone for BIG Mold Making? #3

    I too have personally used the rebound 25 and its a fantastic product. Its a 1:1 mix ratio so you don't need a scale. Very stetchy and strong as hell. And yes you might want to make a lot of copies 'cause like FP said its quality stuff and will last years if you take care of the mold.
  4. BigMarv's Avatar
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    May 5, 2006, 3:29 AM - Re: What's the best value silicone for BIG Mold Making? #4

    BUT, if there are that many undercuts, and it's 3 ft tall,you will want some elasticity and vertical brush-ability .. you should consider their Rebound™ product. Platinum cure (addition cure), offered in a 25 shore hardness, vertical abilities, ect, ect. A bit more expensive, but WORTH it. Easy 1:1 mix ratio. The problem is, you're mold will be around for a while
    Major thanks for the info!

    The rebound sounds pretty tough stuff - would it still require a fibgreglass mother mold?

    Thanks again

    Marv.
  5. fettpride's Avatar
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    May 5, 2006, 3:36 AM - Re: What's the best value silicone for BIG Mold Making? #5

    BigMarv said:
    The rebound sounds pretty tough stuff - would it still require a fibgreglass mother mold?

    Oh yes I would recommend it. I would say that on an item that large, 3/8 to 1/2 inch thinckness silicone (in layers of course), and a rigid fiberglass jacket. Depending on the shape, you may have to make your jacket in sections (maybe even your silicone) to avoid mold lock around your undercuts.

    For instance, in the pic below I see it being at least a 2 part mold.




    FP
    Last edited by fettpride; May 5, 2006 at 3:50 AM. Reason: add pic
  6. BigMarv's Avatar
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    May 5, 2006, 4:00 AM - Re: What's the best value silicone for BIG Mold Making? #6

    For instance, in the pic below I see it being at least a 2 part mold.
    Very close ....It's actually based on the model below, but has a disintegrator pistol in his right hand.



    Do I apply the silicon first and then cut into as few bits as possible that allows me to get it out of the mold?
  7. fettpride's Avatar
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    May 5, 2006, 4:12 AM - Re: What's the best value silicone for BIG Mold Making? #7

    BigMarv said:
    Very close ....It's actually based on the model below, but has a disintegrator pistol in his right hand.
    Do I apply the silicon first and then cut into as few bits as possible that allows me to get it out of the mold?
    Oookee. Well, first and foremost .. I have to ask, so please don't take this as an insult. What kind of molding/casting experience do you have? I only ask because it will allow us to better understand how advanced you are, or not, so that we know exactly what direction to set you in.


    FP
  8. BigMarv's Avatar
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    May 5, 2006, 4:33 AM - Re: What's the best value silicone for BIG Mold Making? #8

    Oookee. Well, first and foremost .. I have to ask, so please don't take this as an insult. What kind of molding/casting experience do you have? I only ask because it will allow us to better understand how advanced you are, or not, so that we know exactly what direction to set you in.
    Insult not taken - complete noob guilty as charged.

    Just dived in with some garden wire, cardboard brown tape and a huge bag of claycrete convinced that if I have enough time and patience I can do it8) .
  9. fettpride's Avatar
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    May 5, 2006, 4:45 AM - Re: What's the best value silicone for BIG Mold Making? #9

    BigMarv said:
    Insult not taken - complete noob guilty as charged.




    Ok. Certainly nothing to be ashaimed of.

    First and foremost, you CAN do it! Time and patience is the key. But I HIGHLY recommend starting with the basics, before diving into a project this complex. It will save you a lot of money in the long run, as the learning curve without it is, well ... pretty huge

    Might I recommend a little bit of a good read first. It's not a big book, but it is the "Bible" that a lot of people have used as their first stepping stone. It's cheap too A lot of great information to get you started. Different types of molds, techniques, and information about various materials and mediums you have to choose from. It won't take you long at all to get a real good game plan set for your mold. From there, it will be much easier to answer any questions you may have, and offer guidance in the right direction once you have some basic understanding.


    The Prop Builder's Molding & Casting Handbook by Thurston James

    http://www.amazon.com/gp/product/155...lance&n=283155

    If you have a problem getting ahold of it, there is probably someone around here that would be happy to pass down their copy

    I hope this helps you out

    FP
    Last edited by fettpride; May 5, 2006 at 4:50 AM.
  10. BigMarv's Avatar
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    May 5, 2006, 5:35 AM - Re: What's the best value silicone for BIG Mold Making? #10

    The Prop Builder's Molding & Casting Handbook by Thurston James
    Got it, and read it cover to cover8) (except for chapter on how to make the DIY vacuform machine).

    As you rightly said though, what I'm attempting is pretty advance stuff, and somewhat out of the scope of the book, which doesn't tackle anything quite as big or complex (I don't even recall a section of using fibreglass as a mother mold).

    I'm probably okay with the finer details, it's just working out the best approach for something this big .

    Soooo.. this is what I think may be the easiest approach (please correct me if I'm wrong):

    1. First I apply the layers of silicone to about 0.5"-0.75"
    2. Then I apply 2 layers of fibreglass on top of the cured silicone.
    3. I dremel the fibreglass outershell into as few parts as possible that will allow me to remove it.
    4. I do the same with the silicone (hopefully in just 2 parts).

    The pistol will be cast separately, and possibly the skirt (would liked to have cast the head separately too, but this is where I'll need the strength).

    Also, might get away with casting the legs, and body separately, with the skirt as a flat plane in between - what do you think?
  11. MARROW SUN's Avatar
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    May 5, 2006, 1:10 PM - Re: What's the best value silicone for BIG Mold Making? #11

    You might want to consider molding the arms, legs, head and "brush" seperatly as well the raygun if your making that.
  12. BigMarv's Avatar
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    May 5, 2006, 3:41 PM - Re: What's the best value silicone for BIG Mold Making? #12

    You might want to consider molding the arms, legs, head and "brush" seperatly as well the raygun if your making that.
    You could be right. I'm trying to peice the procedure together via various forums, and I'm slowly begining to get an idea of what's involved.
  13. fettpride's Avatar
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    May 5, 2006, 3:48 PM - Re: What's the best value silicone for BIG Mold Making? #13

    BigMarv said:
    Got it, and read it cover to cover8) (except for chapter on how to make the DIY vacuform machine).




    Awesome. Not knowing that earlier, it would have been harder to answer questions obvioously, because I didn't know if you knewany of the basics. Didn't want to give you enough to be dangerous otherwise



    BigMarv said:
    As you rightly said though, what I'm attempting is pretty advance stuff, and somewhat out of the scope of the book, which doesn't tackle anything quite as big or complex (I don't even recall a section of using fibreglass as a mother mold).
    Agreed. Again, just wanted to make sure you knew some basics


    BigMarv said:
    I'm probably okay with the finer details, it's just working out the best approach for something this big .

    Understandable. The planning stage is the coolest part in my opinion




    BigMarv said:
    Soooo.. this is what I think may be the easiest approach (please correct me if I'm wrong):

    1. First I apply the layers of silicone to about 0.5"-0.75"
    2. Then I apply 2 layers of fibreglass on top of the cured silicone.
    3. I dremel the fibreglass outershell into as few parts as possible that will allow me to remove it.
    4. I do the same with the silicone (hopefully in just 2 parts).

    The pistol will be cast separately, and possibly the skirt (would liked to have cast the head separately too, but this is where I'll need the strength).

    Also, might get away with casting the legs, and body separately, with the skirt as a flat plane in between - what do you think?
    I think you've got the right idea. I wouldn't cut your fiberglass jacket the way you described however. After your silicone layers have cured, you should clay up parting fins with registration keys for each section you intend on the jacket having. This way, the jacket sections can be bolted back together to contain your rubber properly. Without parting fins and registration keys, your jacket would never go back together as it was originally intended.

    Somtimes I prefer not cutting the silicone on the form after it's been cured, but sometimes you have no choice. In a case like this with as large of a form as you intend on molding, it would probably be the best route. Certainly the fastest. Otherwise you would be applying silicone layers to clay parted sections, which would take forever If you don't mind a little bit of extra flashing to clean up, no bigee.

    As far as sections and pieces go, this will definately have to have seperate cast pieces. For your sanity, as it would be next to impossible to make a casting out of the mold if it were molded complete, as-is. This is what I meant by saying "at LEAST a 2 part mold"

    As MS said above, molding appenages seperately would save a lot of extra time sectioning off your jacket. What he described is like molding a figurine, just on a larger scale.

    You'll most definatelyrun into issues with the protrusions off of the front of the helmet, and the visor of the helmet in relation to the face if you do the head as a whole. You may have to clay up a little more in the cheek areas to keep those undercuts to a minimum, while molding the visor seperately.

    Here's a couple of quick examples ... the first one shows the body as the main support structure, allowing the neck to plug into the head, and the leg stems can plug into the feet (in red). The skirt in two halves. Brush, arms, etc are obvisously sperate.

    The second example would be if you wanted to slush the rest of the body through the bottom of the feet (using the bottom of the feet as the opening to that part of the mold. You could then fill the inside of the body solid after slushing.

    The arms could connect to the body via pegs, or dowels for support.

    There are endless possibilities here. Many different ways of doing it. Hopefully this gives you something to work with It seems like a lot of pieces. But first time out, the more pieces the better I suppose

    I'm sure someone else here will throw you some more suggestions







    On a side note, here is an awesome tutorial that might help you out. Granted, the form he is molding isn't 3 ft tall but it will give you s ome more ideas
    I'm sure


    http://www.danperezstudios.com/works...ng_casting.htm


    FP
    Last edited by fettpride; May 5, 2006 at 3:57 PM. Reason: added link
  14. BigMarv's Avatar
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    May 8, 2006, 3:17 AM - Re: What's the best value silicone for BIG Mold Making? #14

    Major thanks for the info!!! It's finally all coming together.

    Also had some superb fibreglass mold making info from a guy on one of the other forums. I sent him some pics of the WIP and I haven't heard from him since (I'm guessing he may have been a little underwhelmed by my WIP ).

    I'll post a few pics on here tonight and try get a little constructive criticism.

    And by the way Fett Pride, I will need to do the helmet separatley as I will be needing two of these items .

    Big thanks again

    Marv
  15. BigMarv's Avatar
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    May 9, 2006, 3:08 AM - Re: What's the best value silicone for BIG Mold Making? #15

    !!!!NOOBIE ALERT!!!!

    Okay here is my WIP:o (be gentle with me).

    Done a bit more work on the mache version (especially the gun hand), so I'll be ready to do some sanding and some finer detail using the old toilet-roll mache technique.

    So next I'll be cutting it into parts using FettPride's guide so I can give it a little elbow grease.

    After that, I'm not too sure what my options are....

    Can I use plastic primer on paper mache, or will I need an undercoat of some kind?

    Best regards

    Marv

    Here's the original base for my masterpeice



    Next came the papier mache (man did this take a long time - it was like trying to smear cottage cheese on a balloon).



    And what a coincidence...The helmet just happens to be in my size8)

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