Wednesday, August 26, 2009


I invested two flasks this morning; the three Ridgelines Rings and the two custom wedding band carvings. Depending on their size flasks have to dry/cure for at least an hour before the rubber base is removed and they can go into the pre-heated kiln for the burnout cycle.

I've been casting for somewhere around twenty years now, and I'm not really sure why, but I always seem to have a hard time getting myself started on a casting run. I still don't understand it. I guess it doesn't have to make sense, because once I begin investing I'm back into the groove and ready to go!

I'm suspect that some of it is the intense concentration that every step takes. Casting really is as much of an art as it is a science. There are so many different meticulous steps, from sprueing the waxes to the final quench, and so many different things can go wrong at each step . . . And yet that's also part of why I love casting! Well, that and there's just something about pouring molten metal that really appeals to me!

Since these two flasks will be cast in different metals, one in gold the other in sterling, I'll be burning them out and pouring them on different days.

The custom bands went into the kiln at 12:50 AM. I gave them an extra hour at the 300 degree Farenheit range to make sure the carving wax would have enough time to melt and drain out before the temperature was raised.

Then I gave them an extra hour at the end of the heat soak stage when I'd brought the temperature back down to 600 F. Normally for gold I'd cast with the flask at a higher temperature, but because these two rings were being cast together on the same sprue and were such different sizes my experience and double-checking some records said that 600 F would work out just right.

So rather than my standard 5 hour burnout cycle I used a customized 7 hour cycle for this flask.

I pre-heated my Electro-Melt and charged it with the gold right as the temperature was rising to 1850 F. Poured at 7:50 PM. And it was a good pour! It felt good, despite my concerns over the last couple of days about the button and having enough metal, it looked like a good button.

Then the hard part: Waiting for the flask to cool enough to quench. A good rule of thumb for karat gold is 10 to 15 minutes after the red heat has left the button. So you wait . . .

The quench went well. I can often tell if a casting worked by how a flask feels in my tongs as I quench it. This was a good one! A little lively feeling, but not too lively an action (which would mean it was still too hot). This felt just right. Roughly two ounces of gold holds it's heat in a flask filled with almost a pound of investment so I had a good quench.

They went into a glass jar and into the ultrasonic for de-vesting and I got to eat Pat's wonderful and amazing enchiladas for dinner.

And these castings are beautiful!

I don't know a single caster that hasn't admitted to me that, in their own way whatever it is, they pray when they cast. I have a good friend that burns incense on her kiln. I know folks that have their own rituals. I pray. I pray for help and guidance and a steady hand. There are just too many things that could have gone slightly wrong and ruined all of that work for me to ever, ever, be able to take a casting lightly.

Casting is a very exacting science. It's also an art where much is literally out of your hands.

So tonight I'm saying Thank You God for helping these casting turn out so beautifully!

They've been de-vested and are in the pickle in the ultrasonic cleaner right now. I'll photograph them in the morning. Then the fun part comes next . . .

Because of the technical challenge of sprueing these two rings to cast together we're going to have to use a miniature cut off disc to cut them off of the sprue. And then we'll have to re-texture where the sprues were attached before we can mount the heads and set the stones. But it'll be worth it because they turned out so well.

These rings were cast together at the same time from the same gold. And this couple will be wearing them as their wedding bands for the rest of their lives.

And that is part of what makes what we get to do so incredibly special!


A quick shot of Pat's pile of bezels! Each one is made individually for a particular stone. At this point the bezel walls have all been soldered to the base plates.

Saturday and Sunday I roasted skinless chicken thighs for dinner. Each night I cooked a couple of extras. Monday I deboned the leftovers and made this eggplant mozarilla casserole! Wish I had a photo of it after it was cooked. It was even tastier than it was pretty.
More bezels photos soon!


Quick views of some of what Tom was working on Tuesday.

The beginning! Three of our Ridgelines rings waxes, wax sprue, and the rubber sprue base. The ruler will be used later to check dimesnions.

Not pictured is our Dual Therm wax pen.

The first wax is in place. This is our first Ridgelines Ring is a special order for B. through The Jewelers Workbench. (It will be a size 5 1/2 with a peridot mounted for our client when we're finished.)

All three waxes in place. The two outer rings are our third Ridgelines Ring design.

The wax pen is just visible in the background.

Adding molten wax to smooth out the base. This step, one of my favorites, is known as luteing. Molten metal flows very much like water does; there are some differences because of the temperatures involved, but the principles are basically the same. It is very important that there are narrow no choke point that would restrict the flow or cause turbulance when the metal is poured.

All three rings ready on the sprue base. This 3 inch base is a bit large for casting just these three rings, but you'll see why I choose it soon.

A sideview of all three rings in place. Since the wax pen has two stations I'm able to use two different size and shapes of tips at the same time. Which is incredibly handy! The temperatures are controlled with two seperate rheostats.

Top down view with the ruler in use. I'm double-checking to make sure that no edge of any wax is within a 1/4 inch of an inner wall of the flask. I prefer a slightly over-size base and flask because whenever I can I like to have 1/2 inch between any waxes' edges and the flask's inner wall.

Top down view into the flask, ready for investing!

I had to stop as this point. All ready to invest first thing in the morning. Then into the kiln for the burnout cycle, and then casting!

At this stage it's very important to have good records. And I forgot to mention a couple of steps!

First it is important to weigh the empty rubber sprue base before doing anything! Once the waxes are sprued the base is re-weighed. Subtract the empty weight from the finished weight. Since these will be silver rings that number is multiplied by 10.4, which is the specific gravity of the sterling alloy that I'm using.

In this case my casting log tells me that the Total Wax Weight is 2.8 grams. Which comes out to be 29.12 g Metal Weight. To ensure a good casting I'm going to use 35 g to allow for a good full button (the base area).

A good sized button is important because metal shrinks as it cools. The smallest areas will cool and solidify first. The last areas to solidify will be the largest and thickest. By allowing for a large heavy button you help ensure that there is molten metal available for the heaviest areas of the castings as they cool. Otherwise you can have shrinkage porosity to deal with . . .

The last step, before the morning, is to record the dimensions. In this case we're looking at 3" Wide and 2 1/2" Tall (allowing 1/2" headroom above the waxes ~ which helps prevent blowout when the metal is poured).

Knowing these dimensions I consult my investment mixing chart. I'll use 15 oz of investment and 161.7 ml of water. But that's for another day!