After an eternity of sanding, molding, and cursing, I finally finished all of my molds and could start the casting process! The end of this project is finally in sight-- yay!
Part Four: Casting
Compared to all the other parts, casting was probably the most frustrating to figure out but the most relaxing to actually do. Once I got in the groove, settling down to cast all six coasters in one go was kinda pleasant. However, getting into that groove really tried my patience, and I nearly gave up on this project while trying to get a good cast.
The first issue I ran into was bubbling. So much bubbling! This was really discouraging-- after all, if you can't get rid of the bubbles, how on earth are you supposed to get a good cast? The cause turned out to be three different issues that combined together to make a mess. First, I was trying to use a clear-cast but fast-curing resin, which are very much prone to bubbles if you don't have a $200+ vacuum chamber sitting around. Switching to an opaque resin helped a lot. Second, I was trying to cast in 110-degree weather, meaning my pot life of 3 minutes was turning into a pot life of like 50 seconds. Luckily, the fall came in while I was trying to solve my coloring problem that I'll cover later. Third, I kept trying to use every sort of dye except for the expensive stuff meant specifically for use in resin. This was adding moisture to the resin, which in turn made more bubbles. I'd imagine a slow-cure resin or vacuum chamber could help with this, as well, but it was much more cost-effective to just buy actual resin pigments.
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| Some of my ill-fated early attempts |
The second issue I had was deciding on how much of those fancy pigments to use, and then how to consistently measure that amount each time I mix up some resin. Switching to opaque resin meant that I had to add enough dye to overcome its natural white cure color and not accidentally create pastel colors. And since I have six different colors going on, mixing up a large batch for each color (as is frequently recommended) didn't seem very cost-effective. So after many failed attempts and some bad advice off the resin casting forums I visit, my dear future brother-in-law recommended industrial syringes. It feels a little creepy to have a bunch of syringes lying about, but I can get (mostly) exact measurements now, up to 0.01 mL accuracy. After some trial and error, I decided on about 0.1 mL per cup of resin, which I'm using approximately 50 mL of total (25 mL of part A and of part B). That's well under the recommended max of 3% dye per total volume that Smooth-On lists on their site, so it shouldn't be enough to interfere with curing. Hopefully.
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| Fifth time's the charm, I guess? |
The last major issue was simply that the molds ended up kinda crappy, partly because of the issues I listed in the previous section and partly because my originals just weren't that great. Unfortunately, this isn't something I can just fix-- I'd have to completely start over again to get better casts. Considering I still haven't finished version 1 and recently lost all my 3D models in a computer crash, this isn't exactly something I'm willing to do right now. That being said, the pulls I'm getting could certainly look a lot worse, so I'm going to focus on doing the best I can with them until the molds fall apart and need to be remade.
Issues aside, I'm super excited to go demold my casts and see how they turned out. It looks like I could revise the dye measurements slightly on some of the pieces-- especially the red of the Fire Medallion, since it turned into hot pink instead-- but otherwise this round of casts look like they just need to be finished off and then tested. And by tested I mean scattered around my apartment as decorative coasters!
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| My phone isn't great with colors, but here they are in their molds |
Hopefully this has been educational, if not kinda interesting. My next post will cover finishing off the pieces to make them into actual coasters, as well as do a recap on what I did and maybe what tools I used. May the super glue be with you, not on you!
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