Messing about with pewter
 

You may recall I thought I was going to be able to unload a bunch of pewter miniature figurines onto UT for eventual profit! but a wrench was thrown into those plans. And you may even recall that I had given my son a sampling of those figurines, assuming he might like them.

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Most of these things come disassembled. You are supposed to trim the little casting marks off the pieces and glue them together using epoxy. Well, my boy thought they were really cool until it came time to glue them together. Turns out we didn't have any of the appropriate kind of glue in the house. So he tried using a soldering iron to see if he could melt the little guys arm stub and melt the socket and jamb them together. It didn't work. But he did discover the incredibly low melting temperature of pewter.

We got to talking about what we could do with a pound or two of pewter. I explained what little I knew about making molds, and we racked our brains to come up with a cool nick knack to make.

It was decided that we would carve a mold out of plaster of paris, which I did have on hand, and try making a neckerchief slide. A neckerchief is kind of a bandanna that Boy Scouts wear around their necks, and the slide holds the whole thing together. There is an official Boy Scout slide, and we both own one of those, but there is a long tradition of specialty slides being made to commemorate different stuff. We thought it would be cool to make a slide that is unique to our troop, and just show up wearing them one day at a meeting.

So the first thing to do is to mix up some plaster.

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We used yogurt container bottoms to be the molds for the little pucks we were gonna carve into slides.

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While the plaster took an hour or so to set up hard, we needed some source material.

I grabbed a neckerchief because it had a nice embroidered logo I could scan.
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I grabbed some nearby stuff to weigh it down flat on the glass and scan it.
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Then I opened the file in GIMP and trimmed away the extra stuff. Resized it too so it would fit the hockey puck.
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And printed it out. Here is a sheet next to a plaster puck.

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And then to prepare the hockey puck we had to microwave them for a while to drive out all the moisture, and then also sand them nice and flat.

Then we spread newspaper on the dining room table, and we could cut out the seal and use a glue stick to stick it to the puck.
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I got to work with an x-acto knife. These magnifying visor things are awesome.
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It took about half an hour to trace each shape with the x-acto knife. I had to press hard enough to cut through the paper, but if I was too hard, the plaster would crumble. It was a little tricky.
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After I was done tracing all the outlines, I peeled the paper off, and started carving out the depth. this part was very meticulous and tricky. The plaster wanted to crumble. I used a knife to outline shapes and a jeweler's screwdriver to scrape material away and leave a flat bottom.
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This is the finished product and is what the pewter slide will look like. I'm tempted to try to build up some of the letter edges that crumbled away, but I also am contemplating leaving it looking a little more organic and doing less work.
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Next, I have to cover this carved plaster puck with a mold release and pour some other mold material over it to get a negative. I originally thought of just using more plaster, but we tried a test doing that, and it didn't work out too well. So I ordered some high temperature silicone material online. When it comes, I'll post the rest of our progress.

Nifty. You should subscribe to the "Tested" YouTube channel, if you haven't yet. They have a lot of stuff on molds.

Arlington Vagina! :speechls:

Since those toy parts were probably made offshore there's a good chance they contain lead. Melt in a well ventilated area.

The silicon sealer they have in autoparts stores is good for 500 degrees and the Hi-Temp is 650 degrees. Your pewter should melt around 400 degrees, a little lower if it has lead.

I was thinking about getting RTV gasket material that comes in a tube, but I wasn't sure how that would pour over the plaster mold I made. It needs to get into all the crevices without bubbles. Maybe painting it on would work. I don't know.

I ordered a sample size of the material that is meant specifically for this application. So it should work.

Funny how I was fine with doing it the cheap route until after I invested a full day making the plaster mold. Now I don't want to lose a day of work just to save $30.

How funny, I just made a plaster mold to pour some lead ducks for fairing boat lines. (relax, it's only a model)

I learned lost wax bronze casting and mold making in school. You can pour lead or pewter into a plaster mold, but you sort of did it backwards, Make your master positive out of something like wood or wax then make a plaster mold of your master positive. If there are no undercuts the positive should pop out once the plaster sets up. You can use your carved plaster as a positive if you seal it really well and use silicone or something as a release agent. When you've made tour plaster mold let it dry thoroughly. an hour or so in a low oven should do it. You can now pour the pewter into the plaster mold.

Another way to get a really detailed mold for one-offs is to get some dental alginate to make your mold. You can pour several wax positives with it before it dries up or falls apart. Then you can pour plaster over the wax positives, encasing them fully but allowing for a sprue and a vent, You melt the wax out of them (outside, low campfire coals be sure to add sand to the plaster to give it strength) Then while still somewhat hot you pour the metal.

I accidently forgot to take some Bismuth alloy out of my pocket, and brought it home. It's bad if you get fired taking something out but a damn fool if you get caught bringing something back.
This Bismuth alloy melts at 158 degrees F (yes it'll melt in hot water), we used it in tooling to locate bushings in drill fixtures where the old bushing was ripped out leaving a huge hole. It also expands slightly when it cools holding the bushing tight.

My buddy used to do a bunch of wood carving and he bought some silicone mold material so we cast several of his carvings. This one is about 3" high and has good detail. I mounted on a piece of Cocobolo scrap with some stars above and a wood chip that looks like a butte below, calling it, "Between Heaven and Earth"

Crafty!!!

Something to do while his chick did laundry at my place. :blush:

Very nice

ftfy

Very nice Bruce!

You should document the model making here. I'd enjoy that, and I know others would too.