learning the hard way

  1. #1

    learning the hard way

    I've taken my first step into the wide world of molding and casting. I built up one of Jayne's guns from Serenity, and decided to let it take a nice silicone bath.

    Mold came out great, details perfect, and I did the first pour. Only to realize that I put the pour hole lower than the highest point in the gun. As a result, when I filled the mold, no resin got into that upper corner, leaving a pretty significant void.

    I sculpted up the missing part so the resin wasn't a total waste, but let that be a lesson to you! When planning things like that out, don't just worry about undercuts and mold release, also worry about things like "will my resin actually go in!"

    I've got more silicone on order, and will probably document this round of mold making. The good news is that I can at least chop up the old mold and use it as filler in making the new one!

    For curiosity I'm using the smooth-on OOMOO 25 rubber and the smoothcast 300 resin. I'm going to try tinting the next batch with some black dye to make it easier to paint up.

    Here's hoping this round works! This experimenting is getting spendy!!

  2. #2
    drokkul's Avatar
    Member Since
    Mar 2006
    From
    Richmond, KY
    Posts
    987

    Re: learning the hard way

    If you use a very sharp knife you can cut a new pour hole.

    Just make a V shaped cut on one side and then line it up with the other half and cut a V groove on the other side.

    I didn't make the exact mistake that you made, but I did make a mold one time and forgot to place any air vents in it.

    This is how I fixed my problem.

  3. #3

    Re: learning the hard way

    awsome man, I'm a big fan of the Serenity and Firefly series, would like to see some pictures of this. Are there any good resources out there for mold creation or do you have any tips to offer? I am currently making a blue-foam prop of a sword that is on a 28mm pewter figure (so it comes out to about 30x the size), and will be taking it to a friends metallurgy class where she is going to help me make a mold for it, to be cast in Iron. I am hoping I will get to keep, and reuse this mold for resin, but would also like to learn how to make my own molds at home. All I know they use some sort of formula which involves sand to create the mold.

  4. #4

    Re: learning the hard way

    PacoDeth said: View Post
    awsome man, I'm a big fan of the Serenity and Firefly series, would like to see some pictures of this. Are there any good resources out there for mold creation or do you have any tips to offer? I am currently making a blue-foam prop of a sword that is on a 28mm pewter figure (so it comes out to about 30x the size), and will be taking it to a friends metallurgy class where she is going to help me make a mold for it, to be cast in Iron. I am hoping I will get to keep, and reuse this mold for resin, but would also like to learn how to make my own molds at home. All I know they use some sort of formula which involves sand to create the mold.
    i got one of the starter kits from smoothon.com. it was $50 for the silicone, resin, mold release, sealer, a book and a dvd. it's enough to make a couple of small things... nothing fancy, but enough to get you started.

  5. #5
    MARROW SUN's Avatar
    Member Since
    May 2004
    From
    B.C.
    Posts
    608

    Re: learning the hard way

    The 300 isn't the best for taking tint. Off the top of my head I believe its the 325 that is best for tinting.

  6. #6

    Re: learning the hard way

    MARROW SUN said: View Post
    The 300 isn't the best for taking tint. Off the top of my head I believe its the 325 that is best for tinting.
    yeah, i caught that after buying it

    well, there's a lot of tint, so if it does anything, it will be better than pure white.

    there's a reason i'm only ordering the trial sizes of everything right now!

  7. #7
    evan4218's Avatar
    Member Since
    Nov 2005
    From
    Roanoke, TX
    Posts
    1,789

    Re: learning the hard way

    With SC300, I find as long as you bump up the tint you will get a great color... the 325 is all kinds of jacked up with how hard it is when it cures, but perhaps I had a bad batch.

    I dont recommend using OOMOO at all as it rots fairly quickly... for just a few bucks more you can use the MoldMax 30 that is 10 times the silicone quality and by the same maker. If you re do your mold, try it. its a ten cure so you will need a scale but no vacuum degassing required!

    Good luck

  8. #8

    Re: learning the hard way

    evan4218 said: View Post
    I dont recommend using OOMOO at all as it rots fairly quickly... for just a few bucks more you can use the MoldMax 30 that is 10 times the silicone quality and by the same maker. If you re do your mold, try it. its a ten cure so you will need a scale but no vacuum degassing required!
    good to know! there's so much info out there from so many people that i didn't really know where to begin. i jumped in with the 300 and the oomoo basically because they are part of their starter kit.

    i figure if i get to a point where i'm doing any sort of volume i'll have to take it a bit more seriously. for now i'm just hoping to spit out a few jayne guns, since there's a big hole out there for anyone that's into the serenity weapons.

  9. #9

    Re: learning the hard way

    well, i've got a mold that works now. i got 1 pour that came out ok. the other one sort of but not quite... got a void in it due to having the mold angled wrong.

  10. #10

    Re: learning the hard way

    success at last!!!!



    a couple of small bubbles, but that's nothing surprising. it took my 5 failed pours to get it right, but i finally did it!!

  11. #11

    Re: learning the hard way

    Looks awsome. Curious, did you sculpt the prop completely freely or did you use a pistol as a base and build around it?

    Either way, looks awsome and I would like to see a finished product all painted up. Let me know if you plan to sell these, once I get some money rolling in from this new job I might be interested.

  12. #12

    Re: learning the hard way

    PacoDeth said: View Post
    Looks awsome. Curious, did you sculpt the prop completely freely or did you use a pistol as a base and build around it?

    Either way, looks awsome and I would like to see a finished product all painted up. Let me know if you plan to sell these, once I get some money rolling in from this new job I might be interested.
    it's based on an airsoft colt 1911, just like the movie prop

    i got the gun for around $30 and then built up around it with plumbers epoxy.

    i don't know that i'm going to do any number of them... i'm going to clean up the ones i have and sell what i can, but i don't really see myself doing a large run of them or anything.

  13. #13
    evan4218's Avatar
    Member Since
    Nov 2005
    From
    Roanoke, TX
    Posts
    1,789

    Re: learning the hard way

    Looks good, One thing you can do to eliminate surface bubbles is once you pour your mold... rotate it around in your hand. As the resin starts to thicken right before the main curing happens the bubbles will be inside the casting rather then stuck tot he walls of the mold. In some cases this will cause alot of the air to your pour holes too.

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