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Stepside
02-15-2011, 08:01 PM
A friend of mine wants to know what would happen if he melted plated brass. I suspect it is used plumbing parts. He has a vented hood over his melt area and the quantities are small. Will the chrome contaminate the melt or will it evaporate or will it alloy with the other metals in the brass alloy?
The items to be cast are decorative in nature and not structural. Should he expect gas inclusions in the finished product? Also choices of flus to use.

Thanks in advance

Pete

Dr Stan
02-15-2011, 08:09 PM
It's been a while since I poured any castings, but I suspect the chrome will just end up in the dross. There was a foundry supply company near Tulsa OK from which I purchased virtually all of my foundry consumables, but I do not remember the name. You should be able to Google foundry supplies and locate someone who can give you the proper advice.

Stan

rohart
02-15-2011, 08:18 PM
You didn't say, but I assume you mean he has chrome-plated brass to work with.

I do not know, but I'd have thought the chromium would end up on the bottom of the crucible as annoying and difficult to handle snaky tubes. Chromium melts at 1900 deg C, while brass melts below 950 deg C. I'd cut the tubing up, melt it and dig most of the chromium mess out with steel wire hooks.

The melt shouldn't be affected by the chromium.

Black_Moons
02-15-2011, 08:24 PM
I brazed some crome plated stuff to copper once and it bubbled around where I brazed a little. Not sure if the chrome burnt off under where I brazed.. Sure flowed nice.

Rich Carlstedt
02-15-2011, 08:58 PM
You skim it off.
Use Borax powder for flux

Rich

Rich Carlstedt
02-15-2011, 10:31 PM
Some fellows use broken pieces of glass, which works by the way , for flux.
It acts as a barrier to oxygen, but it sure messes up the crucibles and they gradually close up as the glass builds up over time (10-20 melts)

wierdscience
02-15-2011, 11:36 PM
I've melted some,we are in the era of flash Chrome(really thin)it just floated on top of the dross and got swept out in the first skim.

lynnl
02-16-2011, 11:57 AM
I melted some aluminum (or so I thought), that was coated with chrome (or so I thought), and that turned out scary. The chrome, or whatever it was caught fire and was glowing all sorts of scary, exotic colors. And it was giving off huge amounts of smoke and gases.

For awhile I thought it was going to burn up my furnace, my home, my land, and perhaps the whole county! I had visions of "Three Mile Island."

I don't know, maybe it had magnesium in it. Can't say that I really know magnesium. I just remember that these were castings, with a really nice shiny surface. Eventually it burned itself out, but what was left in the crucible was mostly useless blobs of metal and ash clumped together.

I'll not do that again! :D

Alistair Hosie
02-16-2011, 12:31 PM
Just to be safe pour the mix through His majesties old string scantie-loons to remove any impurities( from the scants ) then cast as per ususal? Alistair

Dr Stan
02-16-2011, 01:25 PM
I don't know, maybe it had magnesium in it. Can't say that I really know magnesium. I just remember that these were castings, with a really nice shiny surface. Eventually it burned itself out, but what was left in the crucible was mostly useless blobs of metal and ash clumped together.

I'll not do that again! :D

Yep, that was mag. Had some students working on a pour who were ramming up their sand molds while they were melting their metal in the furnace. Same thing happened to them. Had a nice Roman candle going off in my hot metals lab. :eek:

Got to show off my skills in fire fighting by containing a class D fire.

wierdscience
02-16-2011, 01:27 PM
Hehehe...I leanered the hard way that Late model Ford bell housing are Mag:eek: :eek:

ptjw7uk
02-16-2011, 02:22 PM
Dont forget the longer in the flame(melt) the more zinc you will loose!!
Plus a lot of that brass may contain lead!(good machining)

Peter

oil mac
02-16-2011, 02:43 PM
I have many times in the past, melted & poured yellow brass, filthy stuff! Never allow it to boil, in other words watch your melting temperature, otherwise you get copious amounts of zinc fumes, Frquently some of the old brass moulders who worked for many years with this stuff developed Brass moulders flu or ague, This would upon occasions attack one, and it lastsfor about twelve hours duration &, is not unlike malaria After years of pouring this material i have it also, Many of the old boys i worked beside had an unhealthy complexion (skin yellow) This is caused by the ingestion of years of zinc fumes, Many of the old brass foundries had low roofs, &poor ventilation

however that said, working at home, and taking reasonable care, and considering you are likely only melting a small amount of yellow brass on intermittent occasions during pouring your moulds, wear a dust mask, also after pouring your melt, take a glass of milk With this in mind you should come to no harm
Let me know if you have reached a casting yield of fifty tons, and we might worry on health issues, Remember molten metal is unforgiving stuff, treat it with respect goggles glasses, safety footwear, overalls etc.

As your buddy is not making castings to a high metallurgical specification, I cannot see the chrome plating being detrimental to his finished castings, purely in an ornamental component. If one can obtain non plated scrap, that is a better bet, Cultivate your local purveyor of scrap metal.

For a flux, a small amount of glass for a twenty pound crucible, E.G. as much glass,as will lie in the palm of your hand,( Note this is a weight guide only, I do not want to hear of lacerated hands)
Have your dry glass shards, thrown in to the bottom of the pot, before your metal, As the melt proceeds, the glass will come to the surface, as a cleaning agent, and can be removed with a dry skimmer, Provided you do not go berserk with too much glass, you should keep a clean crucible

Should a foundry supply house be prepaired to sell you a small amount of proprietary flux, without todays rip off "minimum order cost" that is the road to go down.

Dr Stan
02-16-2011, 03:59 PM
Paxton-Patterson supplied a lot of vo-tech type tools, supplies & equipment in the past including foundry consumables. I have not seen their catalog for several years, but you may want to check with them. http://www.paxtonpatterson.com/pp_index.php

bborr01
02-16-2011, 04:57 PM
I bought a furnace and a bunch of brass scrap came with it. I noticed that the brass that was chrome plated had a lot of scuff marks on them that looked like someone had taken a 4 1/2" angle grinder to it.

I assumed that was to let the brass leak out of the chrome plating.

BTW, the widow told me that her late husband did a lot of casting and died of brain cancer.:eek:

I don't know if there was a connection, but I sure am careful about any fumes when I run the furnace.

Brian

lynnl
02-16-2011, 05:09 PM
....
Had a nice Roman candle going off in my hot metals lab. :eek:

.

Yeah, Roman candle. That's a good description of what I had. ...as I recall anyway. It's been several years.
I've now remembered the source. These were pieces from a kitchen mixer set.