I got a pewter Ingot for Christmas this year.
Ingot. What a great word. Ingot. It just feels so great on my tongue. Ingot.
I also like to say words like Crucible. Foundry. Slag. Lost wax casting. Ok, that’s a phrase, but what a great phrase. It makes me feel like a badass blacksmith.
This week I’ve been experimenting with casting pewter into funny shapes, which, it turns out, has a bit of a learning curve. The other learning curve I’m going through right now is getting my chops in Blender, a 3d modeling program which is taking my 3d printing to the next level. So it’s only natural that I’d combine the two: model and 3d print some stuff, make a mold, and cast it in pewter.
I’m having a great deal of fun, but not a whole lot of success right out of the gate. I’m learning a heck of a lot though, so that’s what this post is all about.
Mold Making
I’ve made molds for resin casting before, but I figured the high temperature of metal probably needed something specialized for mold making. I found some Mold Max 60, a high-temp mold rubber by Smooth-on, and thought it would be just the thing.
You’re supposed to mix this stuff in a 100/3 ratio. Ummmmmm. I got out my postal scale and measured and weighed and thought and math-ed and stirred and rethought and remixed and waited, and after 24 hours I ended up with a sticky puddle of red goo. I chucked the whole thing in the garbage. (I also ordered a scale that weighs in micrograms, so when that arrives I’ll give this another go)
Next I tried plaster of paris. I think this might have worked if I’d had a super simple model.. but the two or three things I tried casting ended up permanently embedded in the plaster because I didn’t think it all the way through before casting. You can’t bend plaster to get your original out the way like you can do with mold rubber. More garbage. But, that’s the nice thing about using 3d printing to create your originals.. you can just run off another one instead of throwing away your masterpiece.
Finally I thought to do some research and figure out if the mold putty and mold rubber I’m used to using for resin casting could hold up to pewter’s temperatures. Pewter is a fairly low-temperature melting metal, and it turned out that the Easy Cast mold putty I like to use would be up to the task, provided I didn’t superheat the pewter. Whew. I also got some Amazing Mold Rubber from Michael’s — there was no temperature indication on the box, but in the MSDS it said the flash point was >480 degrees f.. at least slightly above pewter’s melting point of 462-470 degrees f, so that seemed like it might just work.
For the record: It does work, but after 2-3 casts the rubber starts looking a little burnt, and the molds seem to degrade pretty quickly as I use them. But they work well enough.
Texture
My first thought was to make a Fire Pixie pendant — small business schwag is always fun. I spent far too long playing around in Blender and ended up with something I liked. I printed it out, and noticed that even on the highest resolution settings, the face just wasn’t very smooth. Rounded stuff shows the grain of the printer, as it prints layer after layer, coming out almost woodgrain-like, and that wasn’t the look I wanted.
I thought maybe printing it vertically would eliminate some of the grain, or make it less noticeable. And in the 3d printed plastic pendant, it is definitely less noticeable! However, in the final metal version it’s obvious. More than obvious. It looks like it’s made of cheap pine that’s been petrified.
I also tried giving the ABS pendant a quick acetone bath — I dipped it in pure acetone for around 5 seconds and then rinsed it off. This smoothed it down a little bit, and made it look shiny, but nowhere near enough to get the super smooth finish I was going for.
So I gave up on smooth, for the time being, and decided to try printing something where I wanted an interesting texture. I just finished these Auryn Bracers and I adore the Auryn medallion shape from Neverending Story, so I printed out an Auryn all by itself, gave it the acetone treatment, and used the Amazing Mold rubber to make a mold.
This was tricky since there are so many ins and outs and coils in this design. I had to carefully cut the mold away from the back to free my original, leaving a back area that casts incorrectly. But I am delighted with how the first casting turned out.
Lesson here: let the texture of the process work WITH your design rather than against it.
Pewter Casting Other Objects
Next I tried casting a seashell, because I’m a mermaid y’know, and had great success. The natural texture of the shell was picked up beautifully by the Easy Cast mold rubber, and replicated gorgeously by the pewter. Yowza.
Then I tried recreating a cosplay horn that I got from Pan’s House of Horns a few years back. Very cool and talon-y.. but far too heavy to be useful. It’d never stay on my head.
But the thing I’m enjoying most about this pewter casting process is that if a cast doesn’t come out perfect, I can just throw it back into the crucible and melt it down, with 0% waste. Take that, 3d printing gone wrong.
I’m also working on sculpting objects in polymer clay and casting those, but haven’t made anything photo-worthy yet. I really want to get to the point where I can cast metal settings for my LED Galaxy Pendants or other LED jewelry, so that’s coming up soon if all goes well.
I absolutely adore the melding of new tech and old tech, and coming up with designs that would have been difficult or impossible in the past. Huzzah for living in the future!
