Melting Red Brass Sprinkler Valves

[RGerlach]

Hi, I am new to this forum. I have done a little bit of aluminum foundry work but now have a need to pour some parts using Red Brass (aka C836, C83600, 85555, SAE 40, Gunmetal, Ounce Metal, Composition Bronze, Leaded Red Brass etc etc). I have yet to find a source in Southern California and the few places I have talked to want fairly large minimums. So, I want to use up my collection of old sprinkler heads and valves. They do have the hue that I am after so the question comes down to the feasibility of melting down these parts. I have heard good and bad stories from people about their success. What does the forum have to say? Any suggestions, pointers, advice? Any prep requirements besides removing as much non brass parts and corrosion? Any flux? I have been told to throw a glass bottle in the crucible.

Ron

 

[ddmckee54]

Ron:

If you haven't already tried, you might also want to ask this question over on thehomefoundry.org, but it's an un-secured site so your browser might not like it, Chrome and Edge don't like it. But the Internet Exploder that came on this Windoze10 machine is OK with it, go figure.

They are a casting forum, so you'll get a lot more replies to this question.

Don

 

[RGerlach]

Thanks

 

[abby]

Melting and casting gun-metal (red brass) has no secrets . It runs well without the zinc fumes often associated with yellow brass.
Make sure you can reach a temperature of around 1150°C , use a crucible that has only been used for copper alloys , use a flux , this can be made from borax , potash and charcoal , plunge in some phosphor copper and you are good to go.
If buying scrap look for old steam fittings if you want gun-metal , crown wheels are almost always phosphor bronze , aluminium bronze is magnetic.
This pair of exhaust manifolds for 5" gauge locos are cast in gun-metal using lost wax and block moulding with vacuum assistance.

These bracket castings for the same engine show the colour of the metal quite well

Dan​

 

[RGerlach]

Excellent! Thanks, that's the kind of info I needed. I'll report back on my progress.

 

[RGerlach]

Abby

Thanks again for the feedback. Can you enlighten me a bit more? I have a few nuby questions.
1. Potash seems to be a common term for several types of potassium salts or compounds. Is it potassium carbonate or potassium chloride or something else?
2. What are the portions of each and how much do I use (I know that is a pretty wide open question)?
3. Should I buy some phosphor copper shot and just throw a bit in?

 

[SmithDoor]

I used borax used washing machines.
We use to have sprinkler manufacturers here in Fresno CA and you could pickup from scrap yard old castings

Dave

Hi, I am new to this forum. I have done a little bit of aluminum foundry work but now have a need to pour some parts using Red Brass (aka C836, C83600, 85555, SAE 40, Gunmetal, Ounce Metal, Composition Bronze, Leaded Red Brass etc etc). I have yet to find a source in Southern California and the few places I have talked to want fairly large minimums. So, I want to use up my collection of old sprinkler heads and valves. They do have the hue that I am after so the question comes down to the feasibility of melting down these parts. I have heard good and bad stories from people about their success. What does the forum have to say? Any suggestions, pointers, advice? Any prep requirements besides removing as much non brass parts and corrosion? Any flux? I have been told to throw a glass bottle in the crucible.

Ron

 

[abby]

Potash is potassium carbonate , I mix equal amounts of borax and potash , if you have chloride add that as well ! grind some wood charcoal nice and fine , I have a lightning struck oak tree not too far away with large lumps easily detached but I am sure you can source some.
Mix the ingredients well and keep dry.
I use 10kg sized plumbago crucibles and add 2 table spoons of flux to the empty pot , add the metal then sprinkle another couple of spoonfuls on top.
To avoid liquid flux being carried over with the metal you can add a little DRY sand and collect the flux on a bit of steel rod.
Phosphorus copper is available as de-oxidising tubes from several foundry suppliers and I believe I have seen them on Ebay.
The standard type are too large for a small home foundry , they are a copper foil tube with the PCu inside , cut them in half and reseal.
I make my own from domestic 15mm copper pipe. You can get a lump of PCu quite cheap off Ebay. It is a heavy crystalline solid which you can break with a hammer into smaller bits and eventually crush to a gritty powder.
Cut a 2" piece of the copper pipe and squeeze about 1/2" flat in a vise , fill with PCu powder leaving 1/2" to squeeze down to make a sealed unit.
Get a piece of 1/4" or 3/8" steel bar about 24" long and saw down an inch and a half at one end , open out to mak a Y.
Make the Y a tight fit on the de-oxodising tube so that you can plunge it down to the bottom of the crucible of molten metal.
It will bubble a little but nothing violent. Allow the melt to stand for half a minute or so and pour.
Always coat any tools that you use for molten metal with a fire clay wash , this will prevent contamination of the melt and make the tools last longer.
Always pre-warm you plumbago crucibles in the furnace exhaust before placing in the furnace , they can pick up moisture during storage which can turn to steam and cause bits to spall off reducing crucible life.
Can't think of anything else but have a go and let us know how you get on.
Dan.

 

[David Willoughby]

Excellent advice from all posts

 

[MRA]

What do you think about glass, Abby? I have not tried your flux recipe yet (though I will - many thanks) but I have used broken glass which makes a kind of 'sticky lid' on brass and bronze. It seems more important on brass, as when you puncture it with a bit of rod at the end to pull it aside ready to pour, zinc (?) normally lights up and smokes a bit (presumably the glass has excluded oxygen which has slowed or stopped this happening previously).

 

[abby]

Glass does exactly what you have said , but it is not a flux which cleans the melt and refines the grain structure.
The zinc boils and and tries to leave the molten brass , this is good because it prevents hydrogen entering.
When I first started foundry work some 50+ years ago I lived quite close to a company called FOSECO LTD.
This company manufactured products for the then massive UK foundry industry.
I bought several of their products including CUPRIT 49 which is a flux for brass , it works well and produces a fine grained , clean casting .
However I also discovered that the flux ate crucibles ! My crucibles , which are not cheap , were not lasting very long , the acid nature of the flux (flouride I think) was dissolving them.
Most foundry workers , if you can find any , will tell you that brass doesn't need flux and that is probably true but depends really on how clean and uncontaminated your melting stock is .
Aluminium , for example , is detrimental to a brass melt but a FOSECO flux called ELIMINAL will remove it from the melt.
At the end of the day home founders are not trying to produce a cast which meets a government specification.
We just want sound castings that are easy to machine.
So start with clean scrap that you know the origin of , clean off any paint and oil , strip off any steel inserts or rubber seals etc and you will not go far wrong even without a flux.
As stated earlier avoid aluminium bronze , it looks like brass but is slightly magnetic . It occurs in boat propellers and wear parts such as gear selector forks and valve guides , it is hard to cast because it oxidises rapidly , and you don't want aluminium in your brass melt.
Aluminium founders should take care not to add magnesium to a melt , it is easy done !
The melt will almost certainly catch fire but don't panic , cover the surface with DRY sand and carefully remove the crucible from the furnace , park somewhere safe away from any combustibles.
Hope this helps.
Dan.

 

[MRA]

Thanks for the long reply Dan (I forgot to reply, I read your message a while ago!). I must give flux a go next time I am casting brass, and I'll use your recipe - I'm only active at our museum at the moment and there is a lot else going on down there at the moment.

 

[RGerlach]

Abby

I have good news to report. I have had great success melting my sprinkler parts and various other cast red brass parts. I bought one of those small 3KG electric furnaces that use the cylindrical graphite crucibles so all of my melts have been small (under 2-1/2 lbs). I used your recommended flux (Borax, Potash & Charcoal) and Phosphor Copper. I got the PCu in pellet form from Budget Casting Supply. Since my melts were so small I used 1" lengths of 1/4" copper tubing to hold the pellets. I have had absolutely no issues with porosity and the parts have machined up nicely. I also tried some flux from Albral which is described as a generic copper alloy flux. I just added it after clearing the dross and did not add the PCu. Again no porosity but the surface finish was not quite as good.



I am stoked about the results I have had especially after hearing horror stories of bad porosity issue. I wonder if I will have the same good fortune when I step up to bigger melts in my propane furnace. I have read about the need for keeping the atmosphere within the furnace slightly oxidizing because a reducing atmosphere leads to hydrogen gas absorption in the metal (I may have that wrong). This, I suppose, is not an issue with an electric furnace like I have been using.
Thanks for your advice.

Ron