Londinium piston removal - Page 12

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walt_in_hawaii (original poster)
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#111: Post by walt_in_hawaii (original poster) »

Great, Jim! which seals did you get?

Oh Oh... I think I have a problem. My piston is working fine, but I think its a C360 alloy of brass, which is 2-3% lead! They add the lead for machinability. I thought the description of this lot included pipe fittings, which is usually food safe; but when I checked *bay just now, ALL the brass being sold there is C360 alloy in this size, so I almost certainly have C360 as well.
Damn... I'll have to scrap this one (but keep the dimensions) and order low-lead brass. :(

OldNuc
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#112: Post by OldNuc »

I would suspect that the amount of lead that you could leach out of that piston would require a mass spectrometer to detect it.

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redbone
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#113: Post by redbone »

A local espresso equipment reseller in Toronto since the 60's has a collection of commercial vintage espresso machines on display. When I asked if they still use them they stated no due to lead content after they had them tested.
Between order and chaos there is espresso.
Semper discens.


Rob
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LObin
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#114: Post by LObin »

In my opinion, better be safe than sorry. When purchasing a machine, the companies that care about hard metal content in my drinks are high on my list. One of the reason why I went with Londinium in the 1st place.

We find link between hard metals and diseases every day now. In my house, we read labels on food, household products, toothpastes, shampoo, etc. We try to make the best decisions when it comes to what we expose ourselves and our kids to. If the alternative is out there, I would pay a little extra $ for it, whitout questions.

A water testing kit could reveal what's leaching in your water, today. But again, why would I want a little bit when I can have none.

There have been numerous discussions on this matter here and I understand that you can't 100% control the water you drink inside and even more so, outside of your house. Still...

I totally share Bidoowee's views on this when choosing material for his Aurora 2.0. No lead is always better than very little lead.

So. Stainless or lead free brass? ;)
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walt_in_hawaii (original poster)
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#115: Post by walt_in_hawaii (original poster) »

I found a grade of brass called "naval brass" or C464 which has levels of lead so low they are not listed in the chemical makeup. Still has reasonable strength and machinability and thermal conductivity.
I'm looking into the cost of a 2"x12" piece of it... shipping to hawaii always gets ugly.
Stainless is out of the question, the long deeply threaded hole makes that impossible, any tap would snap off long before I could complete that deep a threaded blind hole.
Another option would be to simply cerakote the piston... this will hermetically seal the brass inside a ceramic coat which is chemically inert. Its only about a thoustandth of an inch in thickness and very, very tough... I think I might try this and see if it might be viable.

OldNuc
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#116: Post by OldNuc »

If concerned the cerakote would be my choice.

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Jake_G
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#117: Post by Jake_G »

^^+1
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OldNuc
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#118: Post by OldNuc »

Might want to google <lead leaching from brass> and read up on the issue. Don't forget zinc either. The majority of the information relates to a domestic water system. Your espresso machine is not a domestic water system.

walt_in_hawaii (original poster)
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#119: Post by walt_in_hawaii (original poster) »

Thanks, Rich. I remember seeing a pretty involved discussion here on HB but it didn't pique my interest at the time... :( I should have read it. I'll do a bit more reading on the topic.
The vendor who does my cerakoting is coming by tomorrow to pick up parts, so I took it apart and took off the seals and wiped it off:


Hmmmm... most of the piston is still bright, its been in for what, a week? But I do already see a couple spots with a slight discoloration setting in, darker spots...check out the high spots on the rings 2 and 3 counting from left; this is not coffee stain, so this brass is reactive at normal temps, although it seems to be a very slow process. Still, I'll be glad to have it sealed up. I'll specify a sandblast before he administers the coating to scour it clean.

OldNuc
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#120: Post by OldNuc »

Acetic acid will remove the surface lead and zinc. Plain old vinegar. The brass oxidizes to a brown color and lead in one of those near non reactive materials that is slow to oxidize and lead oxide is white. It is the white pigment on that Rembrandt you would like to hang in the living room. The vast majority of lead contamination in equipment is from lead based solder as there is likely more of that in continuous contact than the actual piston. Problems come into play in domestic water systems where the Ph is >7.0 and there is flowing water.

I think I have some lead test strips here I should check the La Pavoni as it is all exposed brass in the group.