I'm rebuilding the e61 group head on a grimac la uno, after removing all the scale I noticed some of the chrome plating in the mushroom and on the inside of the group is flaking. This parts are constantly in touch with the water and not visible from the outside so I'm wondering if it would make sense to just polish down the remaining plating and leave only brass exposed? Would there be any downside?

Is it new enough to be "lead free" brass?

Probably not, I believe it's probably from 1998, I think lead regulations came a few years later. I was reading this other post about handling lead brass in machines (Addressing Lead in pre-2014/2004 espresso machines) and thought maybe thats what I'll do after removing the remaining plating left

Why not just buy a new stainless version?

That's an option, just hoping to reuse as much as possible since it's still in good shape other than the plating, I might attempt to diy a nickel plating since I already got the supplies needed, but if that goes awry I'll just order a new one

water from my e61 group head had terrible iron aftertaste. That was the reason I sold it after a short time and never looked for another e61 machine. Too many metal parts of various finishes that water travels through until it reaches coffee. Manual Levers are probably the best option in that regard

Hi cafinat Great post that is important for all E61 type Grouphead assemblies.

Corrosion is the single largest concern in any food machine containing Brass and Copper. This is why regular Annual, or at minimum Biennial (every two years) Inspection and Maintenance is absolutely critical. For those who are not handy, finding a good espresso machine repair/maintenance shop/person locally that can do inspections and maintenance is very important. For those who have the time, tools and basic skills needed, doing inspections on the E61 Grouphead Assembly will provide incredible insight into the internal status of an espresso machine, revealing the presence of mineral scale (both Calcium and Magnesium) and any possible Corrosion occurring.

Citric Acid
Despite the concerns of some, Citric Acid solutions (available for about $10 from any Wine or Beer Supply store in 1Kg bags of crystals similar to salt or sugar consistency), are likely not the cause of any corrosion . . . Citric Acid will, however, very efficiently reveal the presence of any Corrosion. Some folks indicate a concern over descaling/Citric Acid treatments of parts removing the Chromium/Chrome-plating . . . but, if flakes of chrome plating are going to come off during descaling, that is a very very . . . very . . . good thing as we should be happy to get these loose bits and bobs of corroded surfaces out of the hydraulic pathways that supply heated water to our coffee powder. Citric Acid is a good thing for cleaning and identifying effects of corrosion and for this reason, worrying about chrome being flaked off is something that could possibly be welcomed or seen as a good thing as it will assist in getting these metal sources out of your food/beverages. The great photo posted by cafinat above of the "Mushroom" valve assembly (found in the upper sleeve assembly of E61 Groupheads), shows that corrosion has been occurring a bit. Using a small jar where the Mushroom valve can be set into it and where Citric Acid can be filled up to the top of the threads (avoiding submersion of the screw/bolt head), will clean any corrosion/chromium plating from the Mushroom. This removal of the flaking chromium can be helped along with use of a simple scotchbrite type kitchen dishwashing pad that is abrasive but not too destructive to the surface of the Mushroom valve/brass/copper.

CORROSION: The Real Issue
Look for Corrosion. Any sign of deterioration of any metal part inside a machine providing food or beverages is worth considering aggressively addressing. Either replacing the part or cleaning/refurbishing it is crucial. Certain metals are not good for human health. Lead for example has been linked to possibly serious health complications. Brass (a copper alloy) uses Lead as a hardening agent in the Copper Alloy. As long as regular cleaning (descaling) and inspection are performed, annually or biennially, any possible or developing risks of metal corrosion/deterioration that can release metals into our fantastic beverages can be avoided. Protecting our health from unhealthy metals such as Lead and Copper, that can be deposited in organ and brain tissues, can be done easily with regular inspection of an espresso machine's components. An E61 Grouphead is a fantastic "Canary in the Coal Mine" to assess the internal health of our beautiful and highly engineered espresso machines By checking the "Mushroom" valve (Upper Sleeve Assembly) it is possible to view how your machine may be doing internally and make a decision whether to do a complete overhaul or more advanced maintenance cleaning/scheduling program.

(1) Here's a photo of an E61 "Mushroom" valve (Upper Sleeve Assembly) from a Bezzera Magica S, purchased recently, that the seller had used and descaled reasonably for 12 years but that had developed several serious faults including a complete failure of the Finder 62.82.8.110.0000 Power Relay (to be expected over 12 years); as can be seen from this initial "Mushroom" valve inspection, this Bezzer Magica S needed a complete overhaul/refurbishing . . .


(2) Here's a video (if you like watching paint dry or grass grow, this video will be your jam!! haha) of descaling of a "Mushroom" valve (Bezzera labeled "Upper Sleeve Assy") . . . about 3 to 5 30 minute Citric Acid session were done, this is one of the first descalings . . . (3) . . . and if you'd like to watch all five of the videos to see the descaling over approximately 2 hours of time (you can use the time scrubber/slider to slide quickly through each of the videos too haha), then here's a link to the YouTube "PlayList" . . .
http://www.youtube.com/playlist?list=PL ... kVe1wDN_O4

(4) And here is a photo of the fully descaled "Mushroom" valve (Upper Sleeve Assembly) after about 2 hours of descaling treatments (videos in the playlist in "(3)" above show the 5 videos of approximately 30 minute intervals, the longest segment the Nikon P600 seems to record) . . . notice the corroded chromium is all off (and not . . . "in . . . mah . . . belly!" . . ., or brain, as a character in Austin Powers might say haha) . . .