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Hello All;

 

I have a couple of boxes of brass pipefittings; and I was looking for some brass flat stuff to make guards and such; so I figured I'd melt some and pour it into a flat thing to make a plate.

Seems simple enough, right ?

Well; I grabbed a grafite crucible, put it in my coal forge and tried to melt stuff in it. And lo and behold; it did; it started to melt. But before I could add some borax, it started to like "burn" green flame; white smoke; and rather voilent. so I turned off the forge and left the place; since I know that zinc fumes are really really bad for you health. I was wearing a respirator rathed for organic and metal vapors (doesn't breathe easily). Then I remembered a frosty quote; feathery white smoke; green flame; evacuate.

But I still didn't end up pouring brass. Anyone any ideas how to overcome this "burning" issue ? Did I overheat it (to boil the zinc)?

 

greetz; Bart

 

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the box says "solid brass" in french & dutch :-) It also has these spiral cone sprayers for sprinklers. I'll attach a picture so you get the idea.

also; I was planning on making a tapered sprue in a two part oilsand casting to reduce porosity and add a teaspoon of borax before casting. 

brass.jpg

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Have you done a web search of the maker to find out what alloy they used, Bart? Most manufacturers want to make the job as trouble free as possible and if there's much machining to be done us a "free machining" brass alloy. Those usually contain lead to make it cut easily and not leave jagged surfaces and edges. This saves on time, tooling and a finishing step. LOTS less expensive. 

Yeah, you overheated it. All the material in a crucible doesn't need to be melted but burn. Borax isn't a degasser, it's flux and floats on the molten surface. You need to stir it in so it'll contact and entrap impurities and particles so they don't make it to the mold.

Casting anything but especially high temp metals is NOT A TRIVIAL undertaking and you've picked one of the trickiest and dangerously toxic alloys to learn on. 

Might I suggest you take a couple classes and try a different metal? Right now those fittings are more valuable as scrap than what they'll turn into in your crucible.

I not being mean, I'm being honest. I don't want to see anybody injured or poisoned if I can discourage a mistake.

Frosty The Lucky.

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You need to research 15% phosphor copper as a degasser. The phosphorus is a reducing agent (deoxidizer). This must be carefully measured so that enough oxygen is removed, yet a small amount remains to improve fluidity.

In addition to phosphor copper, pure zinc should be added at the point at which skimming and temperature testing take place prior to pouring. This replaces the zinc lost by vaporization during melting and superheating. With these alloys, cover fluxes are seldom used. In some foundries in which combustion cannot be properly controlled, oxidizing fluxes are added during melting, followed by final deoxidation by phosphor copper.

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  I thought you said you were going to pour it into a "flat thing" to make guards.  Oilsand can be toxic too.  I used to do a lot of casting and you really cannot be to careful.  A few whiffs of the wrong stuff can be life altering.  I may sound like a nag, but have a care early on.  It will save you some misery.

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Not sure about Belgium but i am sure some place sells them, door kick plates. My local hardware store sells them. They are thin sheets of brass, 1/16" thick (not sure of mm) , 4" W and about 12" long (75mm x 300mm) or so, but for some of the guards i have made i cut strips then glue, screw or rivet them together. I prefer screws and glue, you can grind them off and still leave enough thread to hold it all together. Or i have used 2 pieces of the brass with piece of 1/8" aluminum sandwiched between them. Makes a nice effect with the yellow brass on the outside and the white aluminum in the middle. 

Much safer than trying to cast brass.

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