So, the latest test I did, using a more resin-friendly dye, making sure the containers, tools, my hands, everything were as surgically clean and dry as possible, cured beautifully with no bubbles or delamination.
Except. It made a big ol’ wrinkly fissure in the back which tells me that it was somehow too cold while curing in the oven for three hours. Really? Really?
Alumilite is supposed to be a pretty user-friendly resin. I don’t want to see one of the “difficult” ones!
This is the fifth or sixth time I’ve done this trial and I’m thoroughly sick of looking at these little pink squares. At least the silicone is working nicely so let’s do it. Let’s make mould for Clariel!
Research is annoying, boring, and absolutely necessary. I bet you’re tired of seeing these little squares aren’t you? I sure am. Silicone and resin are both notoriously finicky substances. Each brand and each type has their own particular formula and behaviour. Luckily, I knew to expect this and bought extra to test and fiddle with before casting a big beautiful sword.
Always. Buy. Extra.
So what can you do when your materials are not behaving themselves they way they should? Search online for the answers, do some more digging, ask other artists, watch videos, read tutorials, contact the manufacturer. If it turns out that there’s more than one possibility, you’ll find yourself in the unfortunate situation I’ve been in for the past few weeks.
You have to make the best guess you can as to what went wrong and do it again changing only one thing at a time. It’s tedious and frustrating and you’ll really, really want to make it go faster, but it’s necessary to isolate the problem so you can fix it. If you change more than one thing and suddenly it works, (or messes up even MORE) then you’ll never know where the mistake happened in the first place! The ultimate goal is learning more about how the materials work so you’ll waste less and be more sure of yourself later on.
You’ve all seen my first attempt with Alumilite.
What happened? The resin was too cold. My workshop is only about 17-18 degrees Celsius. (Yeah it’s not so comfy this time of year.) That’s too chilly for Alumilite waterclear to cure and not even a heat gun on the mould beforehand made a difference.
For the second attempt, I put the silicone mould in my mini oven that I use for clay baking and propped the door open. This kept the internal temperature of the oven at a toasty 50 degrees Celsius.
Well, it’s not sticky at least … It cured all the way through, nice and hard, but there were weird, flaky patches on the surface of the resin. What could possibly have caused…
Wait a second. Ah! The plaster “jacket” I made to keep the silicone mould flat and secure was made of gypsum. Why is that important? Gypsum doesn’t conduct heat very well at all. That can be really useful for some projects. For this one, though, it sucked. The plaster caused the temperature of the resin to be inconsistent.
Worse than that, the flaking of the resin actually scratched the silicone mould. That means anything I cast with that mould will have scratches all over it. Greaaaat. So I had to make another mould. I made it double the thickness of the original mould so it could stay flat and secure all by itself.
Ah yeaaaaah! That’s what I’m talking about! The resin stayed nice and toasty throughout its curing and hardened all the way through. No stickiness, no weird bubbles, no probl- Oh. Yeah there are some dark flecks in there. It’s not a uniform pink.
Yeah, the dropper I used to put the dye in the resin had a semi-dried “booger” in it. (I call bits of congealed paint, glue, whatever that gets stuck in the nozzle of something a “booger”. I don’t think that’s the technical term for it.) So the clump of dye came out in the resin and failed to dissolve into it.
But I’m still happy. “Use a clean dropper” is a really easy fix!
As I always say: “There’s no such thing as perfection; only beauty.” So how can we feel better at being forever imperfect? Just have a look at where we started and see how much we’ve grown!
Are you stoked? I’m stoked! Let’s get to the workshop and make cool stuff!
I wanted to have some more positive news for you before I posted again but it looks like that’s going to come a little later than I hoped. Remember the pink plastic coaster thingy I said I was making?
Yeaaah, it’s not supposed to look like that. The darned thing just didn’t cure properly. I’ve been doing more research and realised that my workshop is too cold for curing Alumilite in small quantities like this. (It’s only about 4-5mm thick.)
The plaster jacket I made to hold the silicone mould nice and flat is unfortunately sucking the heat out of the material because gypsum is a substance with very low thermal conductivity. What does that mumbo-jumbo mean? Well it’s cold. And it stays cold. (There’s more to it than that but the coldness is the important bit to this project.)
It ended up sticky and not fully hardened. You can probably see my fingerprints all over it. That’s not good.
So, yesterday I ran an experiment with my mini-oven at work, heating up the resin and holding it at 50 degrees Celsius while it cured. I couldn’t stay for the last hour of its curing because it was my wife’s birthday and I had to go spoil her properly. But before I left, I noticed a few tiny bubbles that should not have been there and it looked like it was separating from the mould in a few places. Not good! But I didn’t see any cloudiness that would indicate it didn’t cure all the way through. If there’s still no clouding when I get to the workshop today, that means we’ve made some progress!
So, why are small things harder to cast with Alumilite than large things? Well, when you mix part A and part B together, the resin has a chemical reaction that causes it to harden. This chemical reaction is exothermic (it gives off heat). If the piece I’m casting is large enough, I don’t have to worry about the mould being chilly. The resin will heat it up nicely for me.
While I’d love to simply go ahead and cast the Clariel patiently waiting for me in its box, and I think it will do fine with its own heat, a sword is a LOT bigger than a wee coffee coaster and will eat up more of the resin. If I should mess up on a sword casting, that would be a very expensive mistake! This is why I’m doing something small first so I can understand how this material works and get a feel for it before I tackle the seraph blade.