Hi chuckclaunch Absolutely brilliant post and fantastic photos and video that will assist many in future without question!

Oxidation on Pure Copper Surfaces
This black surfacing on the Heating Element and Boiler Walls might be a buildup of a Copper Oxide or Copper Sulfide (both black in colour) but possibly a Copper Sulfide may be worth considering if the water is coming from a Well system or if possible Sulfur sources upstream in the water lines leading to the espresso machine have a source for Sulfur (including bacterial production of Hydrogen Sulfides).

Copper Oxides
It appears for Copper Oxides, a patina oxide, there are three stages to Copper oxidation.

1. The first stage is the natural patina named "Cuprite" that neutral Copper metal forms and is pinkish/reddish in colour. This pink patina is evidence of the Cu +1 cation state being present. This process is accelerated by heat, such as in an espresso machine haha!
2. Second stage oxidation: Over time the Copper Patina/surface will continue to oxidize to a black Patina, CuO, called "Tenorite" that is evidence of Cu+2 Cations. This second stage of Copper/Brass oxidation is also accelerated by heat (as in an espresso machine lol).
3. Thirdly, and finally, this second stage Tenorite can, in the presence of water, react with Sulfur Dioxide and Carbon Dioxide (present in air) to create the third stage multi-compound of oxidation composed of three crystalizing molecules called "Brochantite," "Malachite" and "Azurite." The first of these three, Brochantite, is a hydrated Copper Sulfite molecule and the other two (Malachite and Azurite) are hydrated Copper Carbinates. This third and final stage might sometimes be found in advanced mineral scaling inside espresso machines, and may be characterized by the presence of blue and green colors on the copper surface as it fully oxidizes to Cu+2 ions.

Another way to look at black Copper Oxides
Copper exposed to air oxidizes and will often appear characteristically reddish (a Copper Oxide classic red). Once this reddish Oxide is established, pressure, and particularly heat (two sides of the same coin in fixed volume pressure vessel), could potentially transform the reddish appearing Copper Oxide into a black Copper Oxide. These two Oxides (the reddish and black Oxides) then "Passivate" (protect) the surface of the Copper from further rapid oxidizing since the Copper metal has no more exposure to the air or other substances. This does, however, change both the thermal and electrical conductivity of the Copper (exceeded only by Silver and Diamond in pure states). This can inhibit formation of continuity on circuits that can rely on conducting current.

If an espresso machine is running constantly, despite being filled above a Water Level Probe tip, one issue many of the experts above in this thread have mentioned over the years may be mineral scale or other surface interference with a Water Level Probe or the Boiler Walls where continuity may depend on being able to conduct a small detectable current The Stainless Steel Water Level Probe looks great in the photos above with little to no mineral scale or other inhibitors for conducting current. The interior Boiler Wall seem to have a complete coating and that might inhibit to some degree forming continuity between a Water Level Probe and the Boiler Wall to some degree perhaps if this is how the Water Level Sensor is de-energizing the water pump.

Thanks for that amazing explanation @WWWired!

NOTE: This is not advice, just documenting what I did, wrong or not read the whole thread and advice before doing this yourself!

I'll add these pics just to help show what not to do for future reference. @WWWired sent me a PM likely for me to save face but I don't mind him posting that here! I did fully submerge the boiler and heating element among a few other items. The group boiler element I just dunked the element itself. (The portafilter/basket/screen were just in cafiza and just sharing the drying pad by the way, I didn't put those in the citric acid!).

A couple of notes I'll provide for anyone doing this in the future:

• you will see the scale peeling away and it looks amazing, but pull the piece out and give it a quick brush, it may be basically done already without waiting for it to look perfectly clean.
• straight out of the "bath" there was a bit of dullness to the copper and I found with a wire brush it all came off and looked great. for the stubborn parts I used a wire wheel on a drill.

All that said, unless there is some major safety issue I'm going to begin getting it all back together today. I spent some extra time getting the group head scrubbed and dismantled and cleaned the membrane switch contacts (one of them had quit working completely). All the parts still look good and I have all the new gaskets and whatnot in hand so hopefully I'll have her pulling shots again in the next few days!

parts all taking a bath (solution was roughly 2-3 tablespoons / liter with hot water and no more than a few hours on some parts, maxxed out at about 8 hours on the boiler itself.



all brushed and some wire brushing to get the last bits


before and after of the membrane switches, just some contact cleaner and wipe with a paper towel was plenty

One more quick pic of the inside of the boiler. I've read in several places that it's very normal for the bottom portion to remain black-ish?


edit: one more, after it dried a scrubbed one more time with soap:

chuckclaunch wrote:So I started this and it's working great, but just want to double check before I get too far, is it ok if it strips the shiny coating off the outside of the boiler?

The shiny coating on the surface of the boiler is just Nickel plating, it doesn't matter if it strips it off.

Awesome, this is mainly what I was worried about. I don't really care what the outside looks like.

Aaaand now I managed to snap off the stud on the thermostat. I managed to drill out the broken stud but having a hard time finding the part. It is this part, I just don't see this specific part anywhere. I think it's a M5 hole.

Chris' Coffee can probably help you out. They've got a lot that isn't in their web site.

it's a pity you drilled out the stud...I believe what you are holding in your hand is the limit stat. So this is actually good news, as La Spaziale had a penchant for using odd, custom parts on their machines. As you would expect, these were expensive (because they could ask what they wanted).

I say luckily, because limit stats are cheap and easily available, plus they are easy to retrofit to the boiler.

Find a limit stat of about 145C, block up the existing hole. Find a space on the top of the boiler, and drill/tap to small holes about 50% of the way through, to mount the "standard" limit stat you bought, get a machine shop to do this for you if you can't do it yourself.

If you can't find easily the limit stat which bolts down onto the boiler via two mounting holes, then drill and tap one for the limit stat that sits into a hole, or find an M5 stud, put that in the existing hole, drill and tap the top of it and fit a standard limit stat to that. You have many ways of doing this. If the part proves, impossible to find, or very expensive....as it's a 10 - 15 dollar part.

Once you have done this, you won't ever have the same sort of problem again...as normally limit stats don't poke into the boiler, another LS foible. In fact that whole top removable boiler plate was a PITA, and design without much forethought to maintenance/longevity.

P.S. I say 145C, because I can't remember exactly the LS max steam temp, but I think it was 130C, so a limit stat from 145 to 155 would be absolutely fine

Thanks y'all. Yeah I thought about just leaving the stud in but was worried about leaks so went ahead and got it out.
Chris Coffee hooked me up with exactly the right one, $15 ezpz.

A few more updates:

Got group boiler back together, managed to loosen up the steam boiler wires enough to pull out a bunch of extra on that ground wire that's basically shredded (green) so will easily be able to re-terminate that when I get the steam boiler back in. Also cleaned up all the chassis surfaces a bunch.


Got the group head cleaned up, new gasket and put back together. Was nice to to this with the machine flipped over for once, ha!


Found the original tag which I thought was cool


Not 100% sure what this does... seems like a group temperature sensor set up in some kind of epoxy? Any maintenance I should do here while it's easy to get to?

Wrapped up the repairs/maintenance! Very much appreciated for everyone's help in this thread. Hopefully it can help someone else and I'm glad to finally know the innards of this thing well. Hopefully I can keep it going another 10 years or so!

Boiler back in, crumbling wires replaced


My homemade portafilter pressure gauge was a total failure. I just could not get it sealed tight enough. Not sure what the issue was. I tried teflon tape and molykote. It was very close to holding pressure then would shoot a tiny stream out across the room. Any further thoughts appreciated!


Back in business!