# Black dust/debris



## Wando64 (Feb 28, 2011)

The water coming out of my Gaggia Baby often contains some back debris/particles and I am a bit concerned as to what it could be.

I usually notice this when I am de-scaling the machine as that's the time when I run loads of water without the shower screen.

The debris are also coming out of the steaming spout if I run water through it.

I have always cleaned the machine once a month using a sachet of Puly descaler.

Could this be caused by the boiler having reacted to the citric acid and releasing bits of aluminium metal flakes?

Anyone else with this problem? Suggestions?

Thanks.


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## gaggiamanualservice.com (Dec 22, 2009)

your descaler is too corosive by the sound of it. its the boiler lining you are seeing in your cup

mark


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## Wando64 (Feb 28, 2011)

Mark, thanks. Do you think it can be cleaned or is it a case of requiring a new boiler?

What de-scaler do you suggest for the future? The Gaggia liquid one is horribly expensive.


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## jimbow (Oct 13, 2011)

The Puly one should be fine but make sure you leave it in the machine for no longer than 20 minutes before flushing it out and that the machine is switched off during that time.


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## Wando64 (Feb 28, 2011)

I've cleaned the boiler and, boy, what i found was scary.

Serious corrosion manifested in holes and channels, thankfully not all the way through but in places probably as little as a couple of millimetres left of boiler wall.

I have cleaned the boiler the best I could and the machine is now working fine with no particles coming through, however I know the process of corrosion will carry on.

I had the machine for less than two years from new and that's not long for what I paid.

Thinking that all that aluminium must have passed to my coffees has given me plenty to think about.

I am now seriously considering upgrading to a Silvia with its brass boiler. Surely a much healthier option.


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## tribs (Feb 21, 2012)

Scary!

Isn't descaling once a month a bit too often?

Also what type of water do you have / use (for pulling shots)?


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## Wando64 (Feb 28, 2011)

I make on average 7 to 10 drinks every day and I use brita filtered water as in my area the water is very hard.

Even with the brita filter I can see scale building up in my kettle (which I use less than the Gaggia) and therefore I think once a month de-scaling is appropriate, though perhaps it could be reduced to once every two months.

During de-scaling I don't keep the solution in the machine for long (perhaps 10 - 15 minutes) but I usually keep the machine switched on throughout the cleaning process and perhaps this makes the problem worse.

A google search (as well as a search on this forum) indicates that these boilers corrode on all machines to a greater or lesser extent.

I really don't know what to do next. Replace the boiler and carry on for another while or upgrading to a brass boiler machine, however I can see that the Silvia has its own quirks and problems too. I am referring to the cases of boiler burning out due to running without enough water in it, mainly during steaming.

I am happy with the coffee I make with the Gaggia, but a bit concerned about aluminium contamination now.


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## tribs (Feb 21, 2012)

Sounds like the damage has been done but it might be better using bottled water that doesn't cause as much scale, reducing the need to descale so often.

Tesco Clearview or Waitrose Essential are both cheap and soft enough to do the job.

I might strip down mine in the next month or so to check mine. I have never descaled, but I have very very soft water and have been using said spring water of late.


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## jimbow (Oct 13, 2011)

Wando64 said:


> ...
> 
> During de-scaling I don't keep the solution in the machine for long (perhaps 10 - 15 minutes) but I usually keep the machine switched on throughout the cleaning process and perhaps this makes the problem worse.
> 
> ...


The Gaggia boiler is a proprietary design and fairly ingenious in a number of ways. Rather than using an immersed heating element inside the boiler as with most other boilers, the Gaggia heats the boiler wall directly I.e. the boiler itself acts as the heating element.

The boiler is made up of two parts: the aluminium body and the base which is brass. Under normal circumstances, aluminium is highly resistant to corrosion. However, the presence of another metal in contact with the same liquid can, under certain circumstances, give rise to galvanic corrosion. Due to the potential difference between the two metals, the aluminium will be corroded and deposited on the brass (this is the same principle as used in gold and copper plating and also in batteries).

For galvanic corrosion to occur an electric charge must be passed through the metals and both metals must be in contact with the same liquid, which must be acidic.

If your regular tap water has a low pH then you could try using bottled water. Even hard water can have a low pH. Also ensure that descaling solution is left in the boiler for a maximum of 15 minutes and that it is switched off during that time. Also, if possible use a descaling solution with an aluminium specific corrosion inhibitor in it such as the Gaggia branded one, Puly or the Dezcal sachets (not the tablets or powder).


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## Wando64 (Feb 28, 2011)

jimbow said:


> For galvanic corrosion to occur an electric charge must be passed through the metals and both metals must be in contact with the same liquid, which must be acidic.


Therefore I conclude that keeping the machine switched on with a descaling solution in the boiler is a killer.

My reason for keeping the machine hot during descaling was simply based my observations when descaling a kettle i.e. it must be switched on for the descaling to happen quickly.


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## jimbow (Oct 13, 2011)

Yup, always switch it off. If you look on the Gaggia branded descaler the instructions say to turn the machine off but unfortunately do not go into the reasons why. Usually heating the acid based descaling solution would indeed speed up the process of dissolving the scale as you observed with your kettle. However, in the Gaggia with it's unique boiler design, this would have some unwanted side effects.


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## jimbow (Oct 13, 2011)

I would also check the pH of your tap water though because it could well be slightly acidic and causing the corrosion during normal operation. It is also worth considering that hard water can still be acidic. Have a look at Jim Schulman's excellent, if slightly long and complicated, FAQ on water:

http://www.big-rick.com/coffee/waterfaq.html

He speaks specifically about hardness and corrosion and even some measures for preventing corrosion.


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## Wando64 (Feb 28, 2011)

Very interesting article. I will use as a reference once I have acquired the water testing kits.

I can see that by being more careful I could prolong the life of the Gaggia boiler considerably, however I think I pretty much made up my mind to upgrade to a brass boiler as I estimate I've absorbed enough aluminium to last me a lifetime:eek:

Also, would I be right in thinking that corrosion is not really an issue on Brass boilers?


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