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craftgrrl2007-06-11 11:36 am
prop-tart.livejournal.com) wrote in craftgrrl2007-06-11 11:36 am
Large Scale Casting Project
Hi everyone, I know a lot of you do small scale resin casting for jewelry and other projects and I thought I'd show you one of the large scale casting projects I did at work this year. The project is by far the most advanced one I've ever done with successful results, but before you click the cut, be aware that the casting is of a real life sheep's head that I picked up at the local butcher shop. Also, there are a ton of pictures, so dial up users should also beware.
Step #1 Preparation
Here's a pic of me and my new friend 'Fluffy' . To prepare for the moldmaking the head was frozen overnight in our shop freezer.
For a good mold, I first had to fill all the gaps and crevices with clay ( I used Sculpey since it doesn't mess with the silicone like Plastilina can)
Then the head was placed on a board covered with contact paper to give the silicone a smooth bottom.
Step #2 Detail coat
The initial coat of silicone is applied to the head I used Smooth-On Mold Max 30- my silicone of choice since its so simple to use. Since the head was frozen I used a quick setting catalyst (10 minute cure) and since I was brushing on the silicone instead of pouring I used a thixotropic agent to thicken the silicone. After the initial layer cured on the top I peeled the silicone and head off the board and did the underside.
Two more coats of silicone were applied to achieve a final thickness of 1/2 inch.
Step #3 Making the Mother Mold
After the silicone was completely set (I let it rest for about 2 hours) I began making division for the mother mold. Most of the time aluminum flashing is used for this, but since I didn't want to buy more I used posterboard--which works just fine. I also attached a cardboard tube at the back of the head so I would have somewhere to pour the casting material. For the mother mold I used another Smooth-On product called Plasti-Paste which is a low odor more friendly alternative to fiberglass. I spread the paste on one half and let it set and then flipped it over to do the other side. Unfortunately I don't have a picture of this setting, but you'll see the finished mother mold in the next step!
Step #4 Removal of the Head
I won't subject you to the gore that occured when removing the head from the mold-basically I pulled the mother mold apart and cut through the silicone with a matte knife. At this point the head had been at room temp. for almost 8 hours and was totally defrosted. I washed the silicone in the sink with some dish soap to get it shiny and clean and then put the mold back together to prepare for casting the next day.
I also cut a hole in the silicone to match the gap in the mother mold
Step #5 Casting Preparation
There are many ways to clamp the mother mold for casting, I usually use drywall screws. You need to make sure the mold is perfecty aligned so that nothing leaks out during casting.
To keep the mold upright for casting and the curing process I just put it in a bucket. Here you can see that I've measured my casting product. Since the finished head needed to be resilient for use by the actors I used Flex Foam-It! also by Smooth-On. This production is an expanding flex foam which means that it expands by 2.5X after mixed. I eyeballed the amount for my mold and was spot on, though its usually better to over shoot since it doesn't turn out well if you have to put in 2 batches. The mix needed is 2 parts B : 1 part A by volume.
Step #6 Finished Product!
After letting the casting cure (for about 4 hours) I removed it from the mold. If you compare the finished item to the original photo you can see what an amazing level of detail the silicone picks up--there were even tastebuds on the tounge in the casting! Although I am a bit unhappy about the seam
Anyway, that was my project. It was for Sam Shepard's "The Curse of the Starving Class" for anyone interested. I ordered all the Smooth-On products directly from the companies website-the total cost of all the supplies was around $350. But Smooth-On carries trial version of almost all their products for a crafter friendly price (usually around $20.)
Here's a pic of me and my new friend 'Fluffy' . To prepare for the moldmaking the head was frozen overnight in our shop freezer.
For a good mold, I first had to fill all the gaps and crevices with clay ( I used Sculpey since it doesn't mess with the silicone like Plastilina can)
Then the head was placed on a board covered with contact paper to give the silicone a smooth bottom.
Step #2 Detail coat
The initial coat of silicone is applied to the head I used Smooth-On Mold Max 30- my silicone of choice since its so simple to use. Since the head was frozen I used a quick setting catalyst (10 minute cure) and since I was brushing on the silicone instead of pouring I used a thixotropic agent to thicken the silicone. After the initial layer cured on the top I peeled the silicone and head off the board and did the underside.
Two more coats of silicone were applied to achieve a final thickness of 1/2 inch.
Step #3 Making the Mother Mold
After the silicone was completely set (I let it rest for about 2 hours) I began making division for the mother mold. Most of the time aluminum flashing is used for this, but since I didn't want to buy more I used posterboard--which works just fine. I also attached a cardboard tube at the back of the head so I would have somewhere to pour the casting material. For the mother mold I used another Smooth-On product called Plasti-Paste which is a low odor more friendly alternative to fiberglass. I spread the paste on one half and let it set and then flipped it over to do the other side. Unfortunately I don't have a picture of this setting, but you'll see the finished mother mold in the next step!
Step #4 Removal of the Head
I won't subject you to the gore that occured when removing the head from the mold-basically I pulled the mother mold apart and cut through the silicone with a matte knife. At this point the head had been at room temp. for almost 8 hours and was totally defrosted. I washed the silicone in the sink with some dish soap to get it shiny and clean and then put the mold back together to prepare for casting the next day.
I also cut a hole in the silicone to match the gap in the mother mold
Step #5 Casting Preparation
There are many ways to clamp the mother mold for casting, I usually use drywall screws. You need to make sure the mold is perfecty aligned so that nothing leaks out during casting.
To keep the mold upright for casting and the curing process I just put it in a bucket. Here you can see that I've measured my casting product. Since the finished head needed to be resilient for use by the actors I used Flex Foam-It! also by Smooth-On. This production is an expanding flex foam which means that it expands by 2.5X after mixed. I eyeballed the amount for my mold and was spot on, though its usually better to over shoot since it doesn't turn out well if you have to put in 2 batches. The mix needed is 2 parts B : 1 part A by volume.
Step #6 Finished Product!
After letting the casting cure (for about 4 hours) I removed it from the mold. If you compare the finished item to the original photo you can see what an amazing level of detail the silicone picks up--there were even tastebuds on the tounge in the casting! Although I am a bit unhappy about the seam
Anyway, that was my project. It was for Sam Shepard's "The Curse of the Starving Class" for anyone interested. I ordered all the Smooth-On products directly from the companies website-the total cost of all the supplies was around $350. But Smooth-On carries trial version of almost all their products for a crafter friendly price (usually around $20.)