Coffee @lemmy.world fmstrat @lemmy.nowsci.com 3mo ago

Uncoated aluminum boiler with brass group head corrosion risk?

Hi all,

I've got an uncoated aluminum boiler to replace the flaking one in my Gaggia Classic Pro Evo. Given that aluminum boiler coupled with the brass group head will cause galvanic corrosion, what are my options?

I know I can wait for companies to get chrome plated group heads in stock, but I hear the new (since April) GCP Evos are using the brass group head and the uncoated boiler. How are they pulling that off?

Thanks.

10 comments

Isn't there a gasket between grouphead and boiler? I would think a liberal amount of Dow 111 would be what you need. I haven't had one of those apart in years so I can't remember how it goes together exactly.
- My concern more stems from electrochemical replacement plating, where the water acts as a transfer agent.
  
  but that only happens while there is water there, right? so given the limited amount of contact time i think this is not a concern. aluminum has a great capacity for self-passivation too, at least the typical alloys do.
  
  Disclaimer that I have not worked on espresso machines in a bit.
  
  When i did that was usually not a problem, swimming pools filters yes, espresso machines no.
  
  Direct contact could be a problem, though not always. The bolts holding everything together were generally more of an issue, grease helped with that.
  
  The most common issue i saw was caused by water with a high mineral content. But that was scaling more than deposition.
Corrosion at the interface between the two?
According to this chart which specifically looks at baseplates and fasteners, the brass will cause the aluminum to corrode, but not vice versa.

10 comments