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Looking at a furnace

Allen in MT

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I don't think it's hot enough.


I just melt with a propane blower (Weed Burner) blowing into a box I built out of Gypsum sheet rock.


A Bone Crucible works most well.


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Hi Allen,

As long as it reaches 2000+ it should work. Get ya some graphite crucibles, and some borax.

I have found that if you dont use a flux when pouring ingots the top layer will tarnish or oxidize when it cools rapidly. This is probably due to any trace impurites in the gold. It doesn't happen if you are melting 24K. But if you are melting fines, it of course will not be pure.

I use a universal cast iron 1-5 ounce bar mold. This will allow you to pour 1 ounce bars without spilling any flux. Heat up the cast iron mold in the oven on broil right under the element. Then generously coat it with wax, so the gold doesn't stick, and it will preserve the life of the mold. I use a 1 to 1 ratio flux/gold. Pour all the melt in 1 slow steady consistant pour. The flux will float to the top and within a couple minutes you can dump the mold over, the ingot should fall right out. pick it up with some tongs, drop it in water, and the flux will pop right off the ingot. Any remaining flux can be removed by tapping it with the back of a spoon. Use gloves because the flux will be just like glass and you can cut yourself. I cut myself pretty bad once.

I then scrub the ingot on one of those little green SOS pads for dishes, and they come out shinny.

Sorry for rambling, but this little talked about process, is one of my favorites, especially in the off season.

Here is a photo of the new furnace I just bought. Works pretty darn nice. It takes about 10-15 minutes from room temp. to 2010 F.

Good luck, I love smelting/melting gold. It's a blast.



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Hi Allen,

I have used that type. I have both that kind, and another electric lab furnace that is the round donut-type. They are both pieces of crap. They take forever to get hot enough to melt gold even with lead and borax flux agents. AND they use A LOT of expensive voltage to NOT get hot enough. I ended up melting fines with a bone-ash cupel and cheap tank of map gas. I also learned that if you put the torch directly on the gold, the fines get blown all to hell - arrghh! The SMART thing to do is to buy the kind of furnaces they have at A &B Prospecting in Mesa. They heat up extremely fast and run on cheap propane. They also come in four different sizes to fit your volume needs. I'm going to get one for myself.


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Thanks for the replies.

This furnace is from a jewler that used it. it heats to 2200 deree F

A friend of mine bought a propane furnace from A&B but with the loud blast and the vortex it creates it blows the real fine gold 50+mesh out.

I looked at the one you pictured Gus, but then ran across the one I mentioned, so I'm still in the looking stage.

you said one to one mix, like 1 oz gold and 1 oz borax, how fine do you crush the gold??

will be doing everything from minus 16 screen and smaller.


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Borax is cheap stuff, really you will want at least a 1 to 1 ratio. Not by weight, but by a sizeable amount. The more borax the better, but just remember do not fill your crucible over about 40% full. The borax will expand upon first being heated, and you will have a mess.

You can re-use the borax a couple of times. First melt it will be dark green, then it starts to get blacker and will have less viscosity with each pour.

I have found the size of gold does not matter to much. but you will want a graphite rod to stir the melt once it reaches temp. Then place it back in the furnace and let it get back up to temp. Then pour.

That's what turned me on about the furnace I bought, I can stir the melt without having to take the crucible out of the furnace. Matter of fact I don't even need to take the crucible out to pour, the furnace has a handle on it.

You will get the hang of it after a couple pours.


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Don't use the borax from the grocery store such as 20 mule team. It has other stuff in it. Get the stuff from a pottery supply place like Majorine(sp) or go over to the Mesa art center in Mesa and ask a potter over there where they get there supplies. It shouls cost about a buck or so a pound in small amts. You can also get some soft insulating fire bricks at about $3.00 ea and build a little furnace to use with the mapp gas so the flame comes under the crucible. Steve over at gold refiners forum has one he made and sells


Hope this helps Wyndham

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As a goldsmith, when I melt my gold it is important that I protect it as much as possible. I was taught by a very experienced person to use a 50/50 mix of boric acid and borax. Both readily available and cheap. It is not neccessary to use a great amout. It basically turns into a very glass like substance during the melt and will keep your gold covered well. It is also extremely important to break in your crucible or melting bowl. You want to heat it to near red hot and them put some gflux into it, when the flux is melted you need to swirl it around (will be in very slow motion) so the crucible gets coated all over. Let it cool and you are good to go. This is much easier done with a torch, a mapp gas torch will do the trick.

Both boric acid and borax can be found at www.riogrande.com. They also sell some very nice molds to make your ingots, crucibles and tongs, etc.

Have fun, be safe and show some pictures!

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