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Quick mold-making questions

 Post subject: Quick mold-making questions
PostPosted: Thu Mar 19, 2009 4:02 pm 
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Ok, so I've embarked on a little mold-making journey, and some questions have arisen. I am using Micro-Mark's one-to-one / rapid mold rubber because it's easy and it's what I have on hand. However, if I am going to expand my molding activities, I want to explore better options. I know that  Hirst Arts recommends Mold Max 30, but what do you use?

Also, where did you get the other assorted items that are required, like the scale for weighing the mix components, the mixing bowls, the syringes for injecting, the casting ladle for metal casts, etc.? Micro-Mark has some stuff, but can be expensive for items that tend to get destroyed/ruined during casting.

Finally, how do you clean up after the process? I have three mixing cups that have silicone resin residue all over them, how can I clean them?

Any other pearls of wisdom?


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 Post subject: Quick mold-making questions
PostPosted: Thu Mar 19, 2009 4:14 pm 
I use Mold Max 10 by Smooth On for silicon, resin type 321 (off-white, 7 minute pot time), and EaseRelease 200. I still really like MicroMart's rubber-to-rubber mold release.

Visit a hobby store with a lot of remote control thingies. They tend to have supplies of 1 ounce plastic mixing cups. A place near me sells bags of 100 for $6. These can be used for mixing resin (and can be reused, tilt them after pouring and the excess resin can be broken out once hard), and also for measuring the silicon catalyst.

Visit a craft store for wooden mixing sticks. I use the large sticks (12 cm) for mixing silicon, and the tiny sticks (5 cm) for mixing resin.

Visit the grocery store for clear plastic disposable cups, as are frequently found at kegger parties. Use these for mixing silicon, then throw them away.

Visit an office supply store and buy a postal scale. I have discovered that the low precision isn't such a big deal for the 10:1 silicon as long as you work with 3 ounce (.3 ounce catalyst) quantities.

For molds, I use toothpicks for feed channels and clay for the resin well.

Get lots of Legos for the mold forms. The 6-by-1 and 8-by-1 are the most useful. I've ordered lots of these from the Lego webstore.

Foamcore board makes excellent mold platforms.

And above all, while working with resin, WEAR EYE PROTECTION.


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 Post subject: Quick mold-making questions
PostPosted: Thu Mar 19, 2009 4:29 pm 
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I use Smooth-On because they have been reliable.  They are also here in Easton, PA which means I can drive to them and pick it up (saves on shipping costs/time).  :agree:

The scale you can pick up at Wal-mart for $10 although it isn't reliable for small weights.  Luckily Smooth-On allows you to mix by weight or volume.  As for cups and such, I just go to Party City and pick up clear plastic cups that you would use at a party.  They are sturdy and you don't feel bad about tossing them. I also wash out and use juice caps and fruit tubs (those little plastic apple sauce or fruit cocktail containers that are kid sized) when I want to mix small amounts.  This was necessary when I did the Dark Eldar models since the resin amount was so tiny- even with three molds I wouldn't even use a cap full of resin.

Popsicle sticks for mixing sticks.

Don't mix near your models.  :no:  Or in clothes you like.  :oh:

Oh, as for Legos they are great for building mold boxes but expensive.  Megablocks or the knock-off Legos work just as well and are half the cost.  Pick them up at Toys R Us.

And O-man is right - eye protection is a must.  The mold release stuff is great for keeping your molds from deteriorating but it will melt your eyeball.  :_(   Well, maybe not MELT it, but it will do something very, very, very bad.




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 Post subject: Quick mold-making questions
PostPosted: Thu Mar 19, 2009 4:42 pm 
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I bought a scale on ebay real cheap. There are a ton of them out there that have real good tolerances due to food dieters and drug dealers.

Also agree with the lego comment and with not spilling it on anything you really like. I would also suggest wearing gloves or washing your hands really well after pouring. I have gotten some chemical burns because of not doing it fast enough.


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 Post subject: Quick mold-making questions
PostPosted: Thu Mar 19, 2009 4:47 pm 
Latex gloves (cue people to lecture me about nitrile) are the right thing for resin action, action, action.

Silicon is water soluble during the early stages of catalyzing, so it's easy to clean with normal hand soap.


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 Post subject: Quick mold-making questions
PostPosted: Thu Mar 19, 2009 4:49 pm 
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I have gotten some chemical burns because of not doing it fast enough.


I forgot about that!  Yeah, the mixed resin heats up.  Hot enough to burn your skin.  I had a bad experience where I dripped resin on my pajama pants just as it was curing.  It did NOT feel good at all, caused the loss of some leg hair, and ruined a perfectly good set of pajamas.  And I messed up the pour to boot.  Needless to say it was a disappointing day on multiple levels.

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 Post subject: Quick mold-making questions
PostPosted: Thu Mar 19, 2009 4:52 pm 
I use the top of a box (standard US shipping box, or the kind that come off of a box of printer paper) as a little resin-pouring stage. This helps contain spills and localize ickiness.


For two-part molds, I make little pusher-plates out of foamcore board. Those and some rubber bands keep the parts together nicely.


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 Post subject: Quick mold-making questions
PostPosted: Thu Mar 19, 2009 4:58 pm 
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Any metal casting experience? I'm thinking I'd like to give this a try eventually (I suspect there may be less mess involved, with the trade-off being risking setting the house on fire.


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 Post subject: Quick mold-making questions
PostPosted: Sun Mar 22, 2009 4:35 pm 
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Metal casting requires some additional safety precautions over resin, but makes more efficient use of materials than resin.  It also requires some additional equipment over resin.  A few high points are below (in no order, as they pop into my brain).

Metal:
RTV (Room temperature Vulcanizing) rubber; this is red in color and has a greater “lifeâ€Â


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 Post subject: Quick mold-making questions
PostPosted: Fri Apr 24, 2009 2:53 pm 
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Rezzing this zombie thread for one more question...

When casting resin models, what type/brand of resin do you use? I've been using what comes in the micromark casting kit (since I have that on hand), but when it comes time to get more, what should I use?

[and by the way, I want to thank everyone who's posted to this thread, you all been a huge help]


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 Post subject: Quick mold-making questions
PostPosted: Fri Apr 24, 2009 3:08 pm 
Smooth-On's Smooth-Cast 321. Nice tan color, 7 minute pot life, 30 minute cure time.


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 Post subject: Quick mold-making questions
PostPosted: Sat Apr 25, 2009 5:03 pm 
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smooth cast 300, only a minute and half to get it poured but it hardens in only 15 minutes.
another tip. i also am lucky enough to live in the same city as smooth on (so no shipping). they have a "how to" video on a constant loop when you go there. they had a great tip for single part molds. in the video they used a bust, but i've been using it on monoliths and such. lets say you want to mold a reaver titan (not that i'm suggeting stealing from GW). once the mold hardens cut a straight line from the feet and upward to both sides of the titan,  sorry no digital camera or i'd show you a picture. basically it allows you to open the mold like a clam. then (assuming your mold is cube shaped) you can rubber band the mold back in place. i hope this makes sense because it is so easy and the detail is excellent. also the mold does not get into the cuts you made, so no flashing.


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