Monday, March 8, 2010

SPECIAL - Hotglue as a Casting Material

Here's another hotglue-heavy project I've just finished:



The "spiderweb" design on the hilt is craft foam strips coated with a thin layer of hotglue, and the skull is an ornament I cast using hotglue which I poured into a silicone mold.

Here's how I made the skull:

I began by making the model ornament out of modeling clay and then I mixed and poured silicone over that to get my mold. (The clay got kind of smushed up as I removed the mold...)



Casting with hotglue is a very tricky business because bubbles love to form in it when it's warm. To eliminate bubbles, I put the nozzle of my gluegun close to the bottom of the mold and started squeezing slowly:



I went over the entire bottom of the mold, making sure all of the crevasses and spaces had been completely filled. If any bubbles formed anywhere within the mold, I took a pin and pricked them. I had to do it quickly, before the glue started to cool and set.



I set the mold in the freezer and, after a few minutes, the hotglue had completely cooled. I was then able to remove it from the mold. (It popped out rather easily. I love silicone.)



I inspected the surface of the cast object to check for holes or gaps in the surface which had failed to be filled in. These could be dealt with, but it took a bit of artistry to close the holes and build up the surfaces and features that needed to be built up. Obviously, the more practice one has working with hotglue, the easier this type of thing is. After the hotglue had cooled, I took some hobby sandpaper and ran it over the surface of the skull ornament to even it out, (ie: make the newly added glue look just like the cast glue.)



After I was satisfied with the look of the skull, I hotglued it into place on the hilt:



And then just painted it as I would any other surface. (Antiquing it in this case, using a mixture of black and silver enamel.)



So there you go. Why waste time, money and effort casting an object in resin if you can make one that looks just as good (and is almost as strong) out of hotglue? About the biggest problem you'll face casting with hotglue are the airbubbles that can arise in the interior and surfaces of your objects. You'll have to be diligent about popping them, and about making sure that your hotglue fills up ALL PARTS of your mold.

Note: you needn't really be all that concerned about the hotglue melting on you, unless you leave your prop in a hot place (like a sunny lawn or lying uncovered in the back seat of your car on a hot day.) If you cover up your props and armor, you shouldn't have any melting issues (at least, in most parts of the country at most times of the year...)

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