After I descaled my machine I noticed metal flakes in the water
On the Coffeetime forum one of our members made the following post (edited out the specific machine name…because this can happen on any E61 machine with a manual lever, or electric solenoid:
Yesterday I went through the process of descaling my boiler and grouphead.. Its 6 months since I did it last, so I thought I might as well get it done again.
Everything went as planned - and I assembled my machine after, what I thought, was a successful descale. I had drawn some water from the group head to smell it and later taste it to find out if all the descaler had come out (I use a Danish brand of descaler which is completely clear but has a distinct smell) .. Smell was ok, but what I saw in the cup had me a bit worried … - the white inside of the cup revealed a LOT of very tiny metal flakes floating around? What is that? What have I done to my machine?
The water tasted OK - maybe with a hint of descaler on the tongue, or maybe it was just me.
Answer
Nothing to worry about happens on all E61 type groups and all machines with a lever mechanism actuating brass cams in a similar way to the E61, when descaing the brew pathway, people just don't usually notice it. It happens with Citric acid, Puly Baby and other commercial descalers. When you descale the acid strips away the oils within the group. The brass surfaces of the cams operated by the brew lever then rub a bit and produce these tiny tiny flakes that you can see shimmer in the light or in a black cup, in addition some of the chrome plating within the group comes away (this tends to happen slowly over time anyway). Brass is whats termed a "self lubricating metal", but the descaling strips most of the oils away, backflushing with water helps, but you can try the tip below which clears the “flakes” faster.
They will eventually go completely as you pull shots of coffee, but a fast way to get rid of them is to backflush with Puly Caff or similar, this seems to add detergents to the group and also kill any remaining descaler (probably because your running a lot of water through the brew pathway and group), experience has shown this reduces this effect very quickly indeed….but you really should be removing the lever arm and lubricating the cam and cam followers inside the E61 group see e61-group-servicing
Oh I would think drinking the coffee won’t do you any harm, as the flakes are only brass and are caught by the puck anyway.
The reason this doesn’t happen in a lot of non E61 machines is because the mechanisms to release pressure are different and don’t have these surfaces that rub.
Here is a typical example of flakes in the brew water, in a black cup they appear golden, in a white cup they appear black
Note: The reason I know it's the brass cams inside the group, is because I have actually operated the lever 4 or 5 times, with the machine switched off, then switch on and pull the shot, you get MUCH more flakes. I also have no idea why backflushing gets rid of them so quickly, unless it puts a slippery layer of detergent on them, that stays until a bit of coffee oil starts lubricating things?