Author Topic: Aluminum mud - descaler dissolving boiler?  (Read 1752 times)

Offline AndyPanda

  • GUG Regular
  • ****
  • Posts: 69
    • OWC, Classic, Carezza, Coffee, Baby
    • Mazzer Major, Fiorenzato T80, Sunbeam conical
Aluminum mud - descaler dissolving boiler?
« on: June 27, 2017, 12:11:47 PM »
Are there any chemists in the forums?    I have owned (and do own) quite a number of very used Gaggia machines and I am very handy at getting them working well again.   But I have noticed on many of them that when I split the boiler apart I find the insides of the aluminum half of the boiler are covered in a soft grey sludge.  I scrape it off and it has the consistency of peanut butter.   And when you hit it with a high pressure water spray it turns the water a disgusting grey.

My theory, but I have no way to confirm it, is that previous owners have left descaling solution in there too long and dissolved the aluminum.

The water where I live is naturally fairly soft and it tastes good too (I'm very lucky there) so I don't get a lot of buildup, but I do need to remove the scale about once a year.  So once I get the boiler completely clean inside, from then on I never use descaling solution.   I just open up the boiler and the calcium deposits brush right out with a soft toothbrush.  It's usually difficult to open the boiler the first time on a very old one (sometimes a bolt will snap off) but once you get it open and clean, it is then really easy and simple to open up to clean the next time.

I know that for many people, opening up the boiler might sound like a lot of work.  But it really is much easier and quicker to clean it that way than to run descaler through and then pump several tanks of fresh water thru trying to flush out all the descaler.   

Has anyone else encountered the soft, grey sludge inside their aluminum boilers?

Oh... and on the boilers I've got that did have the sludge when I first cleaned them... once I get them clean (right down to solid aluminum) they do not continue to rot.  The aluminum quickly gets a layer of aluminum oxide and stays nice and hard.  I don't try to scrape off the aluminum oxide - I think that is a protective layer and a good thing to have - I just clean the scale off by brushing with a toothbrush and it comes off easily when you don't let it build up for 20 years :).   Here's a picture of the bottom half of an OWC when I open it for the yearly cleaning.  All that white deposit was inside but was just loosely lying there and washed right off easily.
 
« Last Edit: July 19, 2017, 01:04:11 PM by AndyPanda »

Offline AndyPanda

  • GUG Regular
  • ****
  • Posts: 69
    • OWC, Classic, Carezza, Coffee, Baby
    • Mazzer Major, Fiorenzato T80, Sunbeam conical
Re: Aluminum mud - dissolving boiler
« Reply #1 on: June 27, 2017, 12:16:32 PM »
I forgot to mention, I don't even take the boiler out of the machine, I just disconnect the wires that go to the upper half and then use a 1/4" ratchet with extention and allen wrench socket to remove the four bolts and lift the top off.  It makes it really quick and easy.

Here's the same OWC bottom half after brushing out the scale.   
« Last Edit: June 29, 2017, 03:51:34 AM by AndyPanda »

Offline AndyPanda

  • GUG Regular
  • ****
  • Posts: 69
    • OWC, Classic, Carezza, Coffee, Baby
    • Mazzer Major, Fiorenzato T80, Sunbeam conical
Re: Aluminum mud - dissolving boiler
« Reply #2 on: July 19, 2017, 01:03:41 PM »
well I was hoping to get some responses to this topic but so far there have been none.

I did some research and found a test done at UCSC that showed acidic foods (for example with vinegar in them) wrapped in aluminum foil will show presence of dissolved aluminum in the food.  They found that higher temps (they only tested as high as 50C) greatly increases how fast the aluminum dissolves.

For most espresso machines, the common practice is to heat the boiler with the descaler in it.  And even if you aren't deliberately heating the boiler, if you are pumping the descaler through the boiler then you are heating it unless you disconnect the heater wires before powering on the machine to pump.

RO water is also acidic (when exposed to air, like in the machine's reservoir, RO drops to about 5.0ph) and I suspect maybe the dissolved aluminum boilers I've encountered could have been used with RO water.  Over a period of time with the heat accelerating the reaction, perhaps that is it.    Or maybe the boilers I've encountered had vinegar or citric acid descaler left in long enough to cause the grey sludge.

In any event --- I'm still thinking that descaling is best done by opening the boiler and not using acidic solutions.
« Last Edit: July 19, 2017, 01:06:27 PM by AndyPanda »

Offline D4F

  • Global Moderator
  • Grizzled GUG Veteran
  • *****
  • Posts: 1734
    • Gaggia Classic w PID
    • Baratza Forte-AP
Re: Aluminum mud - descaler dissolving boiler?
« Reply #3 on: July 19, 2017, 02:27:12 PM »
If distilled or RO water is used a pinch of baking soda may be used to adjust the ph.  CO2 is absorbed from the air making those waters acidic.  Many say not to use those with aluminum boilers, others say to add the bicarb. Of course you can add the bicarb and then ph test.

I also looked into this a bit in conjunction with "grit" and descale solutions.

http://www.gaggiausersgroup.com/index.php/topic,565.msg4879.html#msg4879

Offline AndyPanda

  • GUG Regular
  • ****
  • Posts: 69
    • OWC, Classic, Carezza, Coffee, Baby
    • Mazzer Major, Fiorenzato T80, Sunbeam conical
Re: Aluminum mud - descaler dissolving boiler?
« Reply #4 on: July 19, 2017, 04:05:14 PM »
I put a small piece of aluminum foil into a glass of white vinegar.  I heated it first but it cooled down quickly.  It's been sitting there for hours and I cannot see any indication the foil has dissolved at all.  No color change, nothing.

Offline D4F

  • Global Moderator
  • Grizzled GUG Veteran
  • *****
  • Posts: 1734
    • Gaggia Classic w PID
    • Baratza Forte-AP
Re: Aluminum mud - descaler dissolving boiler?
« Reply #5 on: July 19, 2017, 05:19:48 PM »
Visible destruction vs ions of aluminum...   There is a lot of information about using aluminum for food and drink.  I think that the soft aluminum coated with oxide might be different than shiny foil.  All that said, long term exposure of aluminum to acid, even relatively mild acid of CO2 dissolved in water should be avoided.  I am still convinced that you can descale with acid, then a good rinse out, and then avoid acidic water.  Some of the CG users claimed in the range of 20 years with a Gaggia, with descales, and no ruined boilers.  Of course the aluminum may have leached out of the boilers and destroyed their memories :)

Offline AndyPanda

  • GUG Regular
  • ****
  • Posts: 69
    • OWC, Classic, Carezza, Coffee, Baby
    • Mazzer Major, Fiorenzato T80, Sunbeam conical
Re: Aluminum mud - descaler dissolving boiler?
« Reply #6 on: July 19, 2017, 08:08:53 PM »
So I'm still puzzled about what caused the aluminum boilers I've seen where the surface layer of aluminum inside the boiler was soft like peanut butter  :-\  Maybe I knew once and those memories have been erased  :'(

 

LIBRARIES

Reference Library

Owners Manuals, Parts Diagrams, Wiring Diagrams, and How-To-Do-Stuff Articles.

 

+-Recent Topics

The Forum is Shutting Down, closing as of Jan 1, 2018 by SusanJoM
December 31, 2017, 08:39:24 PM

Coffee Deluxe by SusanJoM
December 31, 2017, 11:47:12 AM

(Questions) - Homemade pressure gauge for adjusting pressure by SusanJoM
December 29, 2017, 03:19:19 PM

Nice OWC restoration at HB by D4F
December 27, 2017, 04:27:49 PM

Pump leaking from plastic by wjm
December 24, 2017, 05:37:39 PM

Using Thermoblock as preheater by jerryseabridge
December 24, 2017, 11:00:25 AM

Use OWC OEM portafilter for DIY pressure and/or temp gauge? by rcfitz86
December 22, 2017, 03:02:00 PM

Classic, solenoid or pump issue - help needed! by DG Classic
December 15, 2017, 11:32:58 AM

Gaggia Classic Solenoid Spring Question by SusanJoM
December 15, 2017, 10:59:51 AM

Dosing on Gaggia Classic Stainless Steel boiler by benm
December 13, 2017, 06:15:59 AM

Powered by EzPortal