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Bemused - Listening to: The Scales of Zordium
Since I've posted my Necron clones and Proiteus's Zanatorian Machine Cult pieces, I've been getting a lot of questions on how to cast resin. Well, here's how you do it. First, you need the following:
1. Silicone rubber mold mix. It's sold in a box with a jar of silicone and a little bottle of catalyst. Just follow the instructions, mix, and pour. I have a preference for Alumilite's high strength stuff, it only just started to break down after I finished Proiteus's stuff. You can find the silicone at hobby stores and craft shops and will cost about $30.
2. Resin. This stuff comes in a two bottle set, mix in equal amounts and pour into your mold. I use Alumilite's low viscosity resin, which you can get at the same places as the silicone for about the same price.
3. Some Lego bricks. I use these to make pouring molds easier.
4. Polymer clay.
5. The pieces you're casting, obviously!
6. Some paper towels for cleanup.
7. A smooth, rigid surface. I find a clipboard works well for this.
8. Vaseline or other petroleum jelly.
9. Measuring cups. These come with the resin.
10. Some scrap sprue for stirring.
Once you have all these things, you're ready to go. Now here's how you use all this great stuff.
Step one: Build your mold box. Assemble the Legos into a box that's a little bigger than the area of your mold, and put the box on the clipboard.
Step two: Make the bottom mold. Put a slab of clay in the bottom of the box, and then work it out to the edges. Then pull the Lego box away, and press your pieces down into the clay. You may need to sculpt the clay a little to get it to line up correctly with your pieces. I find that pressing the pieces into the clay with the most detailed side facing up saves a lot of work. After you're done, put the Legos back around the clay. Lastly, key your molds. This cuts down on miscasts dramatically. To key a mold, simply poke a flat area of the clay with a narrow object, like the end of your paintbrush, to make a dent in the clay. This will create interlocking features that'll hold your mold together while the resin cures. Make sure you do this in at least two places.
Step three: Pour the first half of the mold. Get out the silicone and catalyst, and mix according to the directions on the bottle. Pour the silicone over the clay and pieces. To cut down on bubbles and other mold errors, you should pour slowly, starting in a flat area of clay with no pieces, and let the silicone flow over your parts. After the pouring is done, sit back and let the silicone cure. It'll take about 24 hours for the stuff to work, so go take a nap or read a book and come back tomorrow.
Step four: Remove the new mold. It's simple, break down the Legos if you have to, but pull the now cured silicone off of the clay. You've just made half of your mold. Now, remove the Legos from the clay, and replace the clay with the mold you just made. You now have a silicone mold in a Lego box on your clipboard. Remove the pieces from the clay and put them in their appropriate places in the silicone. You might have to clean some clay off of the parts before you pour the next part of the mold. Once you're ready, coat all visible silicone in Vaseline. The Vaseline acts like a mold release lubricant, and prevents the silicone from curing to itself. When you're done with that, mix up more silicone and pour the second mold just like the first, and give it the same amount of time to cure.
Step five: Remove the new mold again. Just pull it off after it cures, and it should come right out. You now have a pair of molds to cast whatever parts you want. Now put away all your silicone, Legos, and clipboards, and get out the resin.
Step five: Cast your parts. Before you do anything else, get a piece of your sprue that's about the size of a pencil. Cut off all the extra bits so that you have a smooth shaft, and then whittle an end down to a rounded point about the size of a .7mm mechanical pencil's lead. This'll be used to pop or herd away bubbles when you start casting. First, set out your molds and make sure you are clear on how one fits onto the other, because when the resin is mixed you have about two minutes to get everything done. Next, get your resin and mix equal parts of it in one of the rubber measuring cups. Stir it quickly until it becomes a uniform color, and then pour it into your molds. Fill both molds, make sure you get all the parts you want to cast, and then get your bubble popper and start popping bubbles, or at least pushing them out of the mold. Bubbles are bad, they cause miscasts. The less miscasts you have the less time you need to spend with greenstuff sculpting away bubbles and other annoying things. As soon as you are done, or the resin starts to get tacky, quickly flip one half of the mold on top of the other and press down firmly to flush out extra resin. The resin gets hot when it cures, so don't touch the mold. Give it about five minutes, and it should be stable enough to move. For best results, let the resin cure for ten minutes, then pull your molds apart. You now have extra pieces! Simply pop them out of the thin flashing around them, clean them, get rid of any bubbles with greenstuff, and use! Resin can only be attached using super glue, so be careful of that.
Well, folks, there you have it, a step-by-step walkthrough of how I cast pieces in resin. I hope it helps!