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On 11/15/2019 at 7:13 PM, Brewstillery said:

I’m pretty sure that is a brass alloy. 

I doubt it is actually brass (zinc alloy of copper), since the zinc is an undesirable metal for this purpose, and thermally cycling brass can cause it to degrade. Although I guess it is not impossible, if the interior is coated. More likely a bronze (tin alloy of copper)?

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You may be right.  Especially since the whole head looks like brass and I have never seen that before.

  However, we reworked an older Mueller still here about 3 years ago that had a copper head but the manway was a heavy solid brass manway and it did not have any kind of coating.  Not something that I would put on a still but brass was used a lot for manways and other fittings on older stills of all makes, including the stills of Vendome Copper & Brass Works.

 The Germans still use brass manways on some newer stills.  Today it is probably de-leaded or lead free brass  but in the old days it was just regular old brass with 2% lead added for machinability. 

Also bronze is metallic brown in color, not yellow.  

Interesting fact.  The Chinese call regular copper "red copper" and brass "yellow copper".

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On 11/22/2019 at 12:46 PM, Southernhighlander said:

You may be right.  Especially since the whole head looks like brass and I have never seen that before.

  However, we reworked an older Mueller still here about 3 years ago that had a copper head but the manway was a heavy solid brass manway and it did not have any kind of coating.  Not something that I would put on a still but brass was used a lot for manways and other fittings on older stills of all makes, including the stills of Vendome Copper & Brass Works.

 The Germans still use brass manways on some newer stills.  Today it is probably de-leaded or lead free brass  but in the old days it was just regular old brass with 2% lead added for machinability. 

Also bronze is metallic brown in color, not yellow.  

Interesting fact.  The Chinese call regular copper "red copper" and brass "yellow copper".

Bronzes can be many colors, including gold, depending on the specific alloy makeup. Bronze can be worked, generally not true for brass. Hence, where machined, like for a manway cover, I guess it could be brass, but I would be surprised if the stillhead were brass.

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Either way...there’s some weird two-tone discoloration right above the control panel and it seems like it’s the same in the other picture. 

It reminds me of a 1994 Ford Probe with a pearlescent paint job. Looks don’t really matter it probably makes some great stuff though...

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On 11/23/2019 at 7:37 PM, bluestar said:

 Bronze can be worked, generally not true for brass. Hence, where machined, like for a manway cover, I guess it could be brass, but I would be surprised if the stillhead were brass.

I have no idea whether the still helmet is brass or not  It could just be the colors off in the photo.

  I've never thought about building a brass still helmet but If I wanted to build one, it would not be a problem. Brass is easily worked into all kinds of things such as lamps, spittoons, bowls,  billions if not trillions of ammo casings & primers and on and on.  Our metal spinning machine will do the halves of a brass onion up to 32" in diameter.

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For all of those interested.  The head on the Muller still is not brass or bronze.  It is copper.  

It's a gold color because the copper has been coated with a sealer.  The sealer turned yellow when the copper got hot.  We have used sealers in the past but our sealed columns would turn a darker red when they got hot.  However copper from different places reacts differently.  Heat will cause some to turn lighter and some to turn darker.  The reason the  plated column is not yellow is because it did not get as hot.  Mystery solved.

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Just now, Southernhighlander said:

For all of those interested.  The head on the Muller still is not brass or bronze.  It is copper.  

It's a gold color because the copper has been coated with a sealer.  The sealer turned yellow when the copper got hot.  We have used sealers in the past but our sealed columns would turn a darker red when they got hot.  However copper from different places reacts differently.  Heat will cause some to turn lighter and some to turn darker.  The reason the 4 plate is not yellow is because it did not get as hot.  Mystery solved.

That all makes sense.

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15 hours ago, Southernhighlander said:

I have no idea whether the still helmet is brass or not  It could just be the colors off in the photo.

  I've never thought about building a brass still helmet but If I wanted to build one, it would not be a problem. Brass is easily worked into all kinds of things such as lamps, spittoons, bowls,  billions if not trillions of ammo casings & primers and on and on.  Our metal spinning machine will do the halves of a brass onion up to 32" in diameter.

Both brass and bronze will work harden, but brass is hard to anneal that out, some bronzes may. That also means thermal cycling will further coarsen grain structure in brass, and eventually it might fail. And if you leach out the zinc (which has significant vapor pressure at high temperatures), that's not good. So I probably would not want to use it on a boiler device. On the other hand, it is fine for resistance to corrosion at room temperature, in part because exposure passivates the surface and inhibits further corrosion. Hence, why brass is used for ships.

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bluestar,

Brass is used on most steam boilers and hot water heaters that are built in the US and around the world.  That brass goes through years of thermal cycling and pressure without failure.

We and our competitors put brass components on stills everyday, and those stills get really hot and then cold and operate under pressure and there are no issues with those components even after many years of use.

I would not put a brass column on a still but if I did, I would have zero worries about it failing from thermal cycling.

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