Melting bronze question.

L6steel

L6steel

Joined
Sep 23, 1999
Messages
5,855
Would it harm my heat treat oven to melt some bronze in it just one time?
I have a casting project I want to do and I don't have any other means for melting the bronze that I know of.
Will charcol briquettes in a hole with a blower melt it?
I could rig that up easily enough.
Thanks for any help you can give me folks!!
 
There have been comments about working with brass or bronze will ruin the forge .I have asked in the past exactly how this occurs. I haven't gotten an answer, So I don't know if it's fact or urban myth. In any case pure copper melts at about 2000F and the brasses and bronzes melt at a lower temperature depending on which alloy you have. Any heat source that is hot enough to get to steel forging temp will melt copper alloys.
 
Shouldn't be a problem at all in a heat treat oven, Michael, as long as it will get to temp. Alot of "artsy" mokume is made that way.

The concern with copper and brass in a forge is the opinion of some that the vapors from copper and zinc will form metallic oxides that deposit on steel during the welding process and inhibit welding. Many call this urban myth. I have heard of several situations wherein 1) a brass cartridge and 2) mokume were melted in a forge and it thereafter wouldn't weld until it was relined. I simply don't have an opinion any more, other than the anecdotal reports. I've also heard of an MS who makes mokume in his forge and then cranks it up to over 2600F for a couple hours to burn it out. What the truth of the contamination is I don't know.
 
You will never convince Tom Ferry that brass contamination is a myth. He was doing a forge welding demo at a show and couldnt make the weld for the life of him. He found a brass puddle in the bottom of the forge. It was there by accident but he couldnt weld in that forge until he re-lined it. I have heard of this problem from others also.
 
Is it the zinc ,which is very volatile ? If so do you have to melt it to cause the problem ? Are copper alloys that contain no zinc ok ? Is just annealing a piece ok ?
 
I have never melted copper base alloys in a forge BUT we melted tons of the alloys in our foundry. One thing we learned quickly was that we only poured them just before we relined the the melting pot because of the large amount of solid crud that was stuck to every thing when we were done. Another thing the workers learn early on is if you see white smoke from alloys containing zinc you shut down the power to the melting pot and run for your life. Zinc chills is something you want no part of.
The lower temperature melting copper base alloys were easy to melt and poured much cleaner castings than the high temp alloys. If at all possable I would use a ceramic pot to melt in rather than a metal one to avoid any cross contamination. One of my employees by accident dropped a small piece of steel in a melt of sil bronze one day and before he could fish it out it disolved and we ended up with the hardest bronze I ever saw.
Good luck
 
I think it is the zinc that causes the gas. You could email Tom Ferry. He is more than willing to enlighten everybody.
 
Bruce,

It was Tom's forge I was speaking of when I mentioned a "cartridge" contaminant. Personally, I think it's the zinc. However, when I last mentioned this I caught a bunch of flak, so I was a bit more "undecided" this time. Plain Ol Bill told me of this the weekend after the demo. Shortly after that, I warned another about not trying to make mokume in his forge from a stack of coins and brass discs. He came back a few days later and said "I should have listened, I can't weld steel now."

My personal theory is that it has to do with the temp. I would have liked to ask Tom to burn that forge as hot as he could get it for a couple hours after removing the offending "puddle", and then test the welding capability, were I able to turn back the hands of time....

When I started reading a bit about weld contamination, I learned (not being a welder) that one can actually weld galvanized metal. Apparently, if the zinc is burned off, it'll weld. Also, the steel filler rods I have for my oxy/acetylene rig are copper coated to prevent rust, and they work ok. However, that flame is at about 5600F, so it will volatilize any zinc or copper.

Thus, though I believe there is something to the contamination theory, I have yet to figure out quite what is transpiring, as there are those who move successfully between welding steel and mokume in the same forge.
 
Fitzo,cartridge brass is 70%Cu,30%Zn. Yes zinc fumes are toxic. If you weld galvanized steel and zinc gets into the weld you will have a very week weld.Best to grind off the zinc first.They do weld it(braze) with a bronze alloy.
 
I have just a little question about something connected with this topic.

I make my guards out of 3/4 inch brass and I notch out a section of the brass to be where a finger position will go.

I have ended up with a nice little collection of small sections of brass that were cut off.

each is about 1/2 inch high and a little over 1/4 wide.

I have always questioned if there was any way to reforge such brass into yet another brass guard?
 
It is the Zinc in the brasses and bronze that cause the problem. Zinc is a large portion of monkey metal (potmetal) and burns at around 800 degrees. The residue will contaminate everything, and remain around for a long time.

If you want to melt bronze I suggest that you do it in an open coal forge, but beware the green smoke emmitted from the burning zinc as it is just as dangerous to you as it is to your furnace.

A coal forge is so easily made from junk, I would suggest that you use that method for melting non ferrous metals.

Doc
 
Thanks guys!
Great link Glen, thanks!!
I'd forgotten about the flower pot furnace.
Just dug the book out of my desk, lol! :eek:
 
I built onbe of the gingery furnaces, and with a decent 10 dollar blow dryer it works great. I would recommend the link above as well.

Doc
 
Centaur...

Thanks for the link.

I had a look, it seems easy to do,,,I already have all the stuff I need to work with hot brass....it looks like a summer job,,,you need to be in fresh air...
 
Be careful! This is not steel you are casting!

regardless of what you use for a mold (plaster or sand). If the sand is too wet, or the plaster not cured and cooked off, then you may end up with an explosive result. I don't know about you, but I don't like the idea of having to run from my work too much.

I have heard, read about, and seen what can happen when you are dealing with sand that is too wet. The results are terrifying as the hot liquid metal is balsted all over, and you are running away with the hope you don't end up with it on you.

Doc
 
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