Making My Brother’s Wedding Rings 4: Casting Part 1

Now the action begins.

Casting is a 2-day process and it starts with prepping the wax rings by attaching sprues; essentially little hoses, which will attach to a wee wax funnel where the molten metal will flow in.

Attaching the sprues with a hot wax pen.
Attaching the sprues with a hot wax pen.

The sprues are attached using a drop of hot wax.

Sprued rings, ready for the flask.
Sprued rings, ready for the flask.

Once that’s done, they’re fitted into the base of the casting flask, and its measured to see how much investment is needed.


Investment is an almost plaster-like substance, which fills up the flask and covers the wax rings.  It’s then baked in a high heat kiln overnight. The wax rings dissolve, leaving perfect little hollows, shaped exactly like your rings, and with any and all detail.


Making and mixing your investment is a specialty all to itself.  Trevor, my jewelry instructor of a few years is an expert, and he’s doing the bulk of the work here, and humouring me by letting me “help”. It’s a great learning experience for me; but I’d definitely be in over my head if I had to try this myself.


The investment power can be toxic, so wearing proper protection is a must.

Meaasuring the investment powder and using distilled water are also essentials.  Trevor is also adamant that the mixing technique is precise; using gloved hands to feel for any lumps (just one could cause your new plaster cast to explode in the kiln, or when pouring the gold), and timing the mixing exactly (we have 9 minutes to mix and pour and vibrate the flasks.

Hand-mixing the investment.
Hand-mixing the investment.

Vibrating removes any air bubbles inside which could cause similar unhappy endings to a casting flask, and thus all your hard work.

Vibrating the investment to remove air bubbles.
Vibrating the investment to remove air bubbles.

Once the mixture is just right, it’s carefully poured into the flasks and left to dry for a few hours.  After that it’s straight to the kiln.

photo 3 photo 4

Finished flask from the top.
Finished flask from the top. That little “scoop” is the funnel that we’ll pour the molten gold into.

Once the flasks have been fired for the appropriate time, they’re ready for the next step; melting down the gold and pouring!

That’s tomorrow….

One post-script on this:  this is by no means an exact step-by-step of the casting process.  Casting is a very specialized, very delicate and sometimes dangerous process that should only be done by the experienced, or under proper supervision.  This is my journal of the process of making my brother’s rings, so please, don’t read this and try it at home!

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