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Post by retroprops on Sept 21, 2005 12:25:37 GMT -5
I thought I’d share my method of mold making, I hope this help anyone thinking about molding there own work. 1. Cut a box for the master and make sure you have at lease a ½” inch around it. I use USPS priority boxes. They’re the best IMHO. And imbed the master in clay and punch some key dimples in the clay with the bottom of an X-acto ; I use Roseart modeling clay about a $1 a box at Wal-Mart. 2. Tape up the sides and corners of the box; make sure to tape over any holes where rubber may leak out. Now mix up the rubber, (I use Oomoo 30) at this point I use a cheap artist brush to paint on a first coat this is to eliminate air bubbles in the eye and ear areas. 3. Pour the rest of the rubber over the top of the master. When it cures remove it from the box carefuly by cutting the tape on the corners. 4. Remove the clay, cut away any unwanted rubber. Then brush on a very thin coat of petroleum jelly. Or you can use a Mann release agent, Smooth –On sells them but they’re kind of expensive and work the same as the jelly. 5. Now repeat step 2. 6. when that side is cured take it from the box and carefully pull apart the mold and take out the master. Check the inside of the mold for stray clay. Now you can cut a channel where you like and pour your resin.
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Post by casimir on Sept 21, 2005 15:11:11 GMT -5
Retropops, thank you so much! I've read similar articles and pictorials over the years. While the general technique was the same, there were enough details and tangents to scare me off. Based on your "in the trenches" experience, I feel fairly confident I could make a two-part mold using the same materials I use for one-part molds. (i.e. I could use the silicone-based compound I'm familiar with for the mold. Previous articles went on and on about how the mold had to be such-and-such compounds that cost big bucks per quart.)
As soon as I can get back to the workbench for moe than five minutes, I'll be finding ways to use this knowledge.
Thank you!
C.
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Post by radioscooter on Sept 21, 2005 15:34:26 GMT -5
Steven - very helpful post. Thanks.
I've had some difficulty with the clay sticking to the original pieces and to the new rubber. I've been using Kleen Klay from the Alumilite kit and it worked okay the first times but recently it's been sticking to everything and is a pain to get it out/off.
1) How to avoid this? 2) If it does happen, does anything dissolve that kind of clay easily?
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Post by radioscooter on Sept 21, 2005 15:38:01 GMT -5
Also let me point out something you obviously do but didn't mention that I think is pretty key -
sometime before step 3, punch some holes or shapes in the clay around the item to be molded. These become "interlocks" for later when you are lining up the 2 halves of the rubber mold and seal up the mold nicely.
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Post by retroprops on Sept 21, 2005 16:04:30 GMT -5
Right, I forgot that point!
Never messed with kleen klay, the Rose Art is just sticky enough to work with this kind of molding. The Crayola modeling clay doesn’t stick to anything, and is worthless for this kind of molding. It’s been a trial and error experience for me over the years.
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Post by radioscooter on Sept 21, 2005 16:38:12 GMT -5
I also have to mention that while I don't do a lot of molding or casting these days, I have been trying to duplicate parts I've made for this batcave and a few other little costume parts and I had only tried the silicone that comes with the Alumilite kits. I recently got some of the blue Micro Mark rubber and tried that and there was a WORLD of difference. In my experience the Alumilite rubber was 10 times better than the Micro Mark rubber. I have not tried the smooth-on products yet but am about to for this 1:8 Batmobile I am working on. I have heard good things from you and Will about their oomo 30.
-S
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Post by casimir on Sept 21, 2005 16:48:41 GMT -5
Rose Art clays - check! Scooter, I think I mentioned I had recently switched to Plastil 71-10 for making molds. (Hope I got that number right.) You, of course, pointed out it has platinum in it, if you'll recall, which is why it's so pricey. But man alive wa sit easy to use! Sets in an hour, releases easily, and I got the absolute best molds I'd ever made. Of course, I had graduated from basic latex rubber to Plastil, which is like going from paint-by-number to Rembrandt. But I was pleased. I can't wait to try a two part mold with it. I got it here: www.magicsculpt.com/C.
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Post by radioscooter on Sept 21, 2005 16:59:53 GMT -5
Since we're in this thread - I'll bring this up again and maybe Steven can crack it. I want to do a cowl for these 1:6 Batman dolls out of a softer rubber.
Preferably the same silicone rubber that we mold out of.
Latex is too much like halloween masks and feels weird and as Cas points out - is a lot of trouble to get even thick enough to use. Will pointed out that you need to use plaster molds for latex to draw the water out of it while it cures.
But I'd like to try a high tear strength RTV silicone to get a really nice, pliable, durable mask. Maybe even that Dragon Skin stuff from Smoothon. The issue is - what material do I use to make the initial mold if I am planning to CAST in silicone? Let's say I have an original hard cowl out of say - sculpey. And I want to do a 3 piece mold - the front, back and inside so it stays thin. Other than copper like Henry (and I wouldn't even begin to know how to do that) what do I use? I can't use RTV silicone for a mold to cast the same RTV silicone in right?
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Post by retroprops on Sept 21, 2005 17:49:17 GMT -5
Yea you can cast silicon into silicon, but you have to make sure you use the correct mold release. The petroleum jelly would work, but you have to make sure you get it everywhere and not let it build up anywhere.
I’m waiting on some stuff my distributor had to order for me that he says I can cast silicone with out having to do a mold release. So we’ll see.
Oh and that Micro Mark rubber crap! I use it to mold a lightsaber and it stuck like grim death to the master and the parts that didn’t stick crumbled and split like it had a grain to it. Crappiest stuff I ever used. I called and raised holy hell about it and asked for my money back because that’s their policy, but no luck they said I probably didn’t use enough mold release and they would refund my money. Jerks!
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Post by faithfulbutler on Sept 21, 2005 18:59:30 GMT -5
This is great!Speaking as someone that's soon going to venture into the world of Casting etc all this advice is invaluable to me.Thanks so much for this!
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Post by Figuremaster Les on Sept 23, 2005 11:50:54 GMT -5
This is awesome!
I have only ever used a cup and an one piece mold (which has worked great for me) but this is very interesting.
One question...How do your pour your final casting? I see no visible means of feeding the material in to get a solid cast. Or am I just a dummy?
Don't answer that... ;D
But, no, really...how do you cast from here?
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Post by Wild Willy on Sept 23, 2005 14:47:26 GMT -5
[quote author=angremien One question...How do your pour your final casting? I see no visible means of feeding the material in to get a solid cast. Or am I just a dummy? But, no, really...how do you cast from here? [/quote] Les, I guess you missed Steven's # 6 in the above article. " 6. when that side is cured take it from the box and carefully pull apart the mold and take out the master. Check the inside of the mold for stray clay. Now you can cut a channel where you like and pour your resin." Cutting a channel is refering to making a passageway to fill your casting material like a groove. Steven, Thanks so much for this tutorial. I do my heads in single piece molds useing dixi cups but this looks much better. I will be sure to try this method out and perhaps remake some of my past molds. Great post! Karma for you. Will
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Post by customslab on Sept 29, 2005 0:06:26 GMT -5
a great hints their
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Post by retroprops on Sept 30, 2005 5:56:01 GMT -5
Yea, I just made a general mention of the pour hole for the resin; I prefer the top back of the head mostly because the nose and chin point down, if you pour from the bottom neck area the risk of caching air bubbles it greater. Plus if a deep hole is cut for a bodies neck stump it’s much easier. I learned that the hard way.
Also a tip for resin pouring, always powder the mold with talc, baby powder or some guys use corn starch. This draws the resin into the mold and you have even less of a chance for air bubbles.
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Post by casimir on Sept 30, 2005 6:34:52 GMT -5
Also a tip for resin pouring, always powder the mold with talc, baby powder or some guys use corn starch. This draws the resin into the mold and you have even less of a chance for air bubbles. You mean just sprinkle a layer of powder over each half of the mold before pouring in the resin? I've never eard of that trick. Neat. C.
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