Gaggia Classic - scale problems

[Marg1e]

My Gaggia - to which I am totally devoted - was given to me as present. I live on the age pension, and couldn't possibly afford to buy one. As it was, I had to buy all the wonderful infrastructure: tamper, knockbox, and magnificent Le'Lit grinder.
Nearly a year ago I spent quite a lot on having it repaired for scale problems.
I have since replaced the gasket and the showerscreen mount (the latter with a beautiful shiny metal one, no more pitted aluminium for me !).
I always use filtered water.
I backflush regularly; and every two weeks I disassemble to the base underneath the showerscreen mount and make it CLEAN.
However, I haven't been descaling. This is because I am alarmed by the process. I bought a pack of 2 little bottle of Durgol and ended up throwing them out; the process they stipulated meant that the twin hoses that hang down inside the water contained couldn't reach the liquid made up to descale. I even added the second little bottle and more water, and STILL the hoses didn't reach. So much for all that money.
I tried descaling with citric acid; but the water coming through by then had dropped to a level that meant it couldn't work.
Yes, I'm a total dickhead: I admit it. But I simply didn't understand that you have to descale a Gaggia Classic AT LEAST every quarter.
So. I've taken it in for repairs. Apparently the problem is that its aluminium boiler means it will build up scale very easily. There is a possibility of its needing a new boiler, which, I was told, would make it far too costly.
Is there any way to ensure (providing I can find the money somewhere - at this moment I can't imagine where) that descaling with citric acid on a 3-month basis will REALLY keep my Gaggia working ? Please?

[stilloutthere]

I have heard that citric acid should NOT be used on the Classic as it isnt any good for the aluminium boiler..... However I have no idea what the chemistry is behind it, or why it shouldn't be used, and depending on where you go some will say its okay, and others that it should be avoided at all costs. Perhaps there are some chemists out there that could shed some light on the subject and give a definitive answer as to whether its okay, and if not why not.

Am sure this information is out there somewhere, and I have just missed it, so apologies ahead of time for a request that has probably be answered many, many times before.

I havent been descaling once a quarter, and perhaps I should have. Hopefully the soft water in my area of Victoria will mean I don't need to be as diligent, and the filtered jug water might help..... I know ideally it should be an inline system for my machine, but isnt my house so cant do any major modifications to the plumbing.....

Sorry to hear of your difficulties Margie, I really hope it all works out for you

[shortblackman]

Don't you just fill the tank to mix the solution? Can't remember the ratio, but a dose of descaler and the water to go with it should well reach the level of the hoses.

My GC needed valve replacement due to not taking anywhere near as much care as what you have. Although, when I took it in he didn't seem too phased that I'd never backflushed, and said it wasn't necessary. He was quite sure that the problem was all to do with not descaling regularly enough.

Learnt my lesson that way!

Are you in Melbourne?

[Marg1e]

Nope - Sydney.
I had never attempted the citric acid thing for the reason you first put forward - I'd heard it was very bad for all espresso machines ! Hence my taking the (long) time and trouble to buy the Durgol. And no, the directions are very specific for it: you tip in the contents of a bottle and add the same amount of water. Now that I come to think of it, 125ml X 2 is going to be pretty difficult for ANY water container !
For your interest, I was told - peremptorily, I must add - by one of the moderators on the Gaggia Users Group to use citric acid !
Having done some more research, I find the boilers cost around $80, so I'm not sure why the bloke at the repair place indicated that replacing the boiler would be prohibitively expensive ... Perhaps he's talking hours to do the work ...

[deegee]

Hello Marg1e, I have a working Gaggia Classic, and a couple of others that I am modifying / restoring.
I am a big fan of these little machines and I have learned quite a bit about them over the last few years.

I de-scale mine with lemon juice, which is citric acid - a weak organic acid - even weaker when diluted 50/50 with water, which is usually recommended when it is used as a de-scaler. I flush with two or three tanks of clean water to ensure no juice is left behind.

I had heard that citric acid was bad for aluminium, so as an experiment, I cleaned up the base of an old Gaggia boiler and put it in full strength lemon juice for a couple of hours. I could see little or no difference - maybe it was not quite as shiny, but if so, it wasn't much.
Heat speeds up chemical reactions, so I heated it up and left it simmering for half an hour, then left it in there for another hour to cool down. By now is was not as shiny - about the same dull gray as the outside of the rest of the boiler, but no worse. So now I have no hesitation descaling with lemon juice, or citric acid and recommending it to anyone.

Depending on what kind of filtered water you have been using, you probably don't need to descale all that often anyway

Unless they have been cut short, the water hoses on your Classic should reach the bottom of the tank. On some very old classic's they are fixed in place where they come through the chassis centre plate, but newer models are just pushed through a hole in the plate and there is usually some spare length inside the upper housing. If you pull down gently on them, you should be able to get them to reach the bottom.

The cost of having a pro tech replace the boiler would probably cost more in labour than in parts, even though the job would probably only take an hour or maybe less.

Hope this helps. Cheers, deegee.

[burr]

Hmm I don't think many users would suggest lemon juice is a good idea for the internals of a machine. You want things entering your boiler to be as pure as possible, besides commerical descalers are probably cheaper than lemons anyway. Citric acid can DEFINITELY corrode aluminium, its a matter of concentration and time (and temperature).

There are two processes to descale, either through the use of acids, or chelators. Normally weak, chelating acids such as acetic, citric, malic or tartaric are used. These are fine for most metals, but aluminium doesn't hold up very well to strong acids. Hence the sachets gaggia sells not only contain citric acid, but also the basic sodium citrate to buffer it out. Plenty of people use citric acid to descale their gaggias without any issues, but doing it too often when there isn't scale will slowly result in boiler corrosion, and more concerningly dissolved aluminium in your coffee. A small amount of citric acid every 6 months might be OK, but I still wouldn't recommend it.

When I first got my gaggia I took the showerscreen off with the aluminium backplate. There was thick, orange scale as the previous user brought the machine over from the UK. After physically scraping most of the scale off I soaked it in cafetto, and saw the plate fizz (hydrogen) while forming a dark gray layer which scrubbed off after. Not cool!

[deegee]

Hmm I don't think many users would suggest lemon juice is a good idea for the internals of a machine. You want things entering your boiler to be as pure as possible, besides commerical descalers are probably cheaper than lemons anyway. Citric acid can DEFINITELY corrode aluminium, its a matter of concentration and time (and temperature).

Yes, it DEFINITELY can, if you leave aluminium in a strong solution of citric acid it will start to discolour after two or three days, and corrosion will set in after a few more days. I'm suggesting a weak solution for less than an hour in total.
Do you have any actual experience of weak citric acid actually corroding ally ?? . Have you done any testing to confirm your opinions ??.

QUOTE " After physically scraping most of the scale off I soaked it in cafetto, and saw the plate fizz (hydrogen) while forming a dark gray layer which scrubbed off after. Not cool! " QUOTE
Where in my post did I suggest descaling with Cafetto, or even mention it ??. Cafetto is not citric acid, it's not any kind of acid, it is a mix of sodium carbonate and sodium percarbonate so how is it relevant to this discussion?!.

[burr]

I just thought people backflushing their gaggias with cafetto might want to be informed, there was no suggestion you were telling people to descale with it.

There's no need to get so upset, I said a small amount of citric acid might be OK. I just don't think statements such as the following are wise to put on a public forum.

I have no hesitation descaling with lemon juice, or citric acid and recommending it to anyone.

I have not personally performed any experiments with aluminium but the first result of a google search finds the article "The corrosion of aluminium and aluminium alloys by citric acid and citric acid-salt solutions". I couldn't be bothered to read all of it, a quick browse shows 0.1M citric acid (21g/~4 teaspoons per litre) caused corrosion when heated. The citric acid concentration in your 50% lemon juice would be similar.

[Marg1e]

I cannot lay hands on Gaggia's own product: can you advise me where to obtain it from, please ?

[shortblackman]

Sure I've seen it in Harvey Norman. But I've always bought something else that lists Gaggia as one of the list of brands it works on. Naïve? Seems to work.

[sprezzatura]

It's chiefly a law of diminishing returns: citric acid in a too strong solution will pit aluminium. The pitting will facilitate scale build up. This being said, I use citric acid and it works fine. I use hydrochloric acid and it works great for stubborn scale on stainless steel boilers. The prohibitive cost is really tech time. I charge a different rate for bench time as opposed to call out repairs insitu. I think most techs would do this - especially if you find a Gaggia enthusiast-tech.

[MrJack]

I have not personally performed any experiments with aluminium but the first result of a google search finds the article "The corrosion of aluminium and aluminium alloys by citric acid and citric acid-salt solutions". I couldn't be bothered to read all of it, a quick browse shows 0.1M citric acid (21g/~4 teaspoons per litre) caused corrosion when heated. The citric acid concentration in your 50% lemon juice would be similar.

I saw the same article but don't have a current subscription to wiley to see the details. The author did mention a 10°C increase in temp roughly doubled the corrosion rate. The rate itself wasn't given.

It is worth noting that the article was written from the perspective of using aluminium for vessels containing citric acid in an industrial context. This is long term exposure, and unless we are talking very high rates, it is possibly not relevant for occasional exposure from descaling.
The only issue I can see would be the potential to remove the oxide layer, which if done frequently could be a problem.

Edit: The NACE Corrosion Survey database has corrosion rate data for an aluminium alloy (3003/5154): 20-50 metres per year for a concentration of 5-60%.
This is absolutely huge in an industrial setting where you typically look at < 0.5 mm / yr, and a design life of > 10 yrs.

That said, its only 0.1 mm/hr at 107°C.

The rate for acetic acid was much lower @ < 20 m / yr.

Caveat - your alloy may vary

[JojoS]

Marg1e - there is a Gaggia Users Group forum that you can check out for maintaining your Gaggia Classic. I use 2 tbs. of Citric acid dissolved in 1 liter of tepid water to descale my Gaggia classic. I've been using it bimonthly for a couple of years now and have not encountered any problems. I also backflush with espresso cleaner every fortnight. Both maintenance procedures are done with shower screen and plate holder removed.

[Dimal]

Why not just contact the good people at Cafetto?

They are a very helpful bunch and should be able to direct you to the correct cleaning/descaling agent to use...

Mal.

[TC]

Clean Machine Triple Action Domestic Descale Liquid is marketed as safe for Gaggia