floepie Senior Member Joined: 16 Sep 2009 Posts: 9 Location: NY Expertise: I love coffee
Espresso: Gaggia Classic Grinder: Gaggia MDF
Posted Mon Oct 21, 2013, 2:21pm Subject: To backflush a Gaggia Classic or not to backflush?
So today I inquired about blind filter availability via email with a trusted espresso machine dealer. They came back with advice not to backflush with this particular machine because of the internals made with aluminum. Apparently, the cleaning agent typically used with the backflushing can wear away aluminum. It sounds like sound advice, but to what extent are we talking about here, given the exposure to said solution is so relatively short? Is this something to be genuinely concerned about? I've also learned that Gaggia themselves say to avoid this cleansing maneuver. Yet, I see many backflush tutorials and vids specifically using the Classic.
SJM Senior Member Joined: 17 Nov 2004 Posts: 1,706 Location: CA Expertise: I love coffee
Espresso: SAMA, Gaggia Classic Grinder: K-10PB, Rancilio MD-50 Vac Pot: no like Drip: no like Roaster: HotTop
Posted Mon Oct 21, 2013, 2:43pm Subject: Re: To backflush a Gaggia Classic or not to backflush?
Let's start with the fact that the solution you will backflush with is a detergent (Cafiza is a good one) and would have no negative impact whatsoever on aluminum. Actually since that was the only reason they gave for you NOT to backflush, you can just ignore them and do it. Or, of course, you can continue drinking dirty coffee.....:-))))
Here is an article on the WLL site that talks about backflush and noted the manufacturer recommends against backflush. I have seen it written on other sites about Gaggia. I am only noting how the concept got started and keeps getting spread. I backflush.
VanHlebar Senior Member Joined: 20 Aug 2005 Posts: 23 Location: Cincinnati, OH Expertise: I love coffee
Espresso: Gaggia Classic Grinder: Brataza Vario Roaster: Bohemor 1600
Posted Wed Oct 23, 2013, 10:04am Subject: Re: To backflush a Gaggia Classic or not to backflush?
So then I have maybe a really "dumb" question. Sorry...but just how does one backflush the classic then? Do I need to purchase something as since the manufacturer suggests NOT to do it, I am guessing I don't have the required equipment to perform it?
steamer Senior Member Joined: 11 Feb 2005 Posts: 893 Location: socal Expertise: I live coffee
Espresso: Expobar Brewtus IV R Grinder: Mazzer Mini-B Baratza... Vac Pot: Krubs Moka Brew, vacPot Drip: TechV, and many more Roaster: Hottop
Posted Wed Oct 23, 2013, 12:10pm Subject: Re: To backflush a Gaggia Classic or not to backflush?
Not that I am a guru and only having my classic a short time, whats the difference of doing a backflush and the OPV operation of during a backflush or even pulling a shot. I think once the pump hits a dead end the opv pops open and drains off. This could happen on both pulling a shot and a blind basket. Does anything beside water go thru the OPV?
Posted Thu Oct 24, 2013, 5:10pm Subject: Re: To backflush a Gaggia Classic or not to backflush?
Whoever is giving you such information regarding the aluminum corrosion is severely mistaken. They are mixing up what occurs with, and what chemicals are used, during backflushing and descaling.
When you backflush, you use a detergent. Modern detergents are much like the soaps of old made with lye and fats. The same rules apply, these chemicals remove oily residues. When you backflush, NO CHEMICALS HIT THE BOILER. Think about it, when that solenoid valve opens up the point is to relieve the pressure in the PF by allowing it to vent down a tube into another reservoir (like a drip tray). If the fluid found its way back into the boiler....well that wouldn't be good at all because the following shots would be affected. To put the story all together, the Gaggia boiler is what's aluminum. So, even if the detergent did harm aluminum (and it doesn't), it wouldn't matter anyway.
The dealer giving you that advice is mixing up backflushing with descaling. Descaling chemicals are acids (usually citric acid or tartaric acid). These chemicals are mixed with water, put into the water reservoir, and run through the entire machine (boiler and all). Acids do harm aluminum so you'll want to do some research on the proper way to descale a Gaggia machine (I employ a weaker acid solution for shorter periods of time) to avoid such problems.
As others have mentioned, Gaggia recommends against backflushing. We aren't too sure why this is. The most believable reason I can think of is that Gaggia is worried about hot liquid splashing around and leading to injury...who knows. The weirdest thing is that Gaggia actually makes an acid-based descaler that can, indeed, harm the machine if not used properly.
I backflush once a week and descale every 2 months but it depends on how many shots you make and how hard your water is, respectively.
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