Machine Resoration - Descale Question
Hey, guys.
I just started refurbishing a lemon of a 1997 Brasilia Portofino. I've take the boiler out and completely apart and given all the fittings, copper lines, and the boiler itself a few descale baths and have a question.
When I took everything apart, the insides looked like relics from the Titanic. Seriously, very scaled up. I used Urnex Dezcal (citric acid, aluminum salts, and sulfamic acid) in a five gallon bucket, sumberged the boiler and all the fittings, copper plumbing, etc. and left them in for 30 minutes for each bath (per instructions). The first bath went really well with tons of fizz and jets of sludge coming off. It took care of the vast majority of the scale, leaving only a layer of black hard scale on some portions of the inside of the boiler and heat exchangers and a lot of bright, shiny copper. The second bath accomplished nothing, leaving the same black layer. The same with the third bath.
Since the above method isn't doing it for me anymore, I'm ready to change angles of attack and use a prolonged straight citric acid soak. Here's where my question lies. I've dug through as many forums and sources as I can find and some people are raving about letting their boilers soak for a week while others swear that you can do serious damage to the copper after only a few hours. Right when the discussions seem to be heading in a direction of consensus everyone gives up their positions.
I know that it depends on the strength of the solution and amount of scale because as the acid dissolves scale it becomes more basic and eventually neutralized. I don't want to let it sit for a week in a neutralized solution that's not doing anything but I also don't want to walk away for a couple hours and return to a bucket full of loose copper where my boiler used to be.
Here's the question: Is there a general rule of thumb for the length of time scaled copper boilers can effectively soak in a reasonably strong citric acid bath without damaging it?
Thanks!
I just started refurbishing a lemon of a 1997 Brasilia Portofino. I've take the boiler out and completely apart and given all the fittings, copper lines, and the boiler itself a few descale baths and have a question.
When I took everything apart, the insides looked like relics from the Titanic. Seriously, very scaled up. I used Urnex Dezcal (citric acid, aluminum salts, and sulfamic acid) in a five gallon bucket, sumberged the boiler and all the fittings, copper plumbing, etc. and left them in for 30 minutes for each bath (per instructions). The first bath went really well with tons of fizz and jets of sludge coming off. It took care of the vast majority of the scale, leaving only a layer of black hard scale on some portions of the inside of the boiler and heat exchangers and a lot of bright, shiny copper. The second bath accomplished nothing, leaving the same black layer. The same with the third bath.
Since the above method isn't doing it for me anymore, I'm ready to change angles of attack and use a prolonged straight citric acid soak. Here's where my question lies. I've dug through as many forums and sources as I can find and some people are raving about letting their boilers soak for a week while others swear that you can do serious damage to the copper after only a few hours. Right when the discussions seem to be heading in a direction of consensus everyone gives up their positions.
I know that it depends on the strength of the solution and amount of scale because as the acid dissolves scale it becomes more basic and eventually neutralized. I don't want to let it sit for a week in a neutralized solution that's not doing anything but I also don't want to walk away for a couple hours and return to a bucket full of loose copper where my boiler used to be.
Here's the question: Is there a general rule of thumb for the length of time scaled copper boilers can effectively soak in a reasonably strong citric acid bath without damaging it?
Thanks!
Replies to This Discussion
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Permalink Reply by Mike Sabol on
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My experience is with CLR. And I do not use it straight, I typicaly dilute at about 7:1. I have seen the CLR do some damage to various copper items, espessially fittings and threaded joints, but have left the body of the boiler in a solution overnight with no ill effects. I've also been heating the solution to 200F. I think the heat helps.
In the second and third baths did you use new solution? I've often found that when the solution hits it's carrying capacity I have to start again with fresh stuff. You could very well have tapped out your descaler with that first active bath.
One question to ask yourself is if the leftover scale is really going to be an operational problem. You might just say good enough and proceed to rebuilding your machine.
If the remaining scale is actually a problem then I would recomend using a new batch of the same stuff you had success with before, and heat the whole thing up and then leave it for a while. Check it every hour or so and if the scale isn't budging leave it over night. I've had many a tank seem to be encased in scale only to be nearly clean when I came back in the morning.
I'm not sure there is a rule of thumb in these kinds of matters. It all depends on the chemistry, both of the scale and the solution.
I would also be very careful of a highly concentrated solution. The CLR I use makes the copper soft along the surface of contact and can gradually compromise the integrity of the metal. Because of the softening of the surface of the copper I have found that I have needed to flush an ungoddly amount of water through the boiler to get the CLR to rinse out. I have put together machines in the past without a good enough flush and end up getting CLR suds for two days. All I can say is rinse with A LOT of water before you put it back together. I know this isn't the rule of thumb you were looking for but I hope this helps. Good luck and have fun!!
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Permalink Reply by Brady on
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I'm interested in this too... about to start two restorations. I'd considered Dezcal, but that stuff is ridiculously expensive - as I recall it was at least $20 for enough to do one boiler? I'm considering other options... thanks for the CLR tip, Mike.
Ryan, would you mind sharing links to some of the more useful discussions you've found on this topic? I'd just planned to dive in and surf around for a while, and still will, but often you find a real gem of a discussion by pure dumb luck and I don't want to miss anything good.
Thanks!
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Permalink Reply by Ryan Soeder on
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Mike, to clarify, I used fresh solution and very hot water for each soak. I ran out of Dezcal after the third bath and am really not wanting to buy more since, as Brady pointed out, it's crazy expensive and mainly made up of citric acid anyway. Also, I'm sure that the level of scale left in the boiler would not be an operational problem but I started this project with the goal of being completely thorough and just feel like I'd be letting the scale beat me if I give up at this point - a problem I'm sure I'll seek therapy for in the future. ;)
Brady, here are some of the more helpful sources I've found. If you happen across anything further, I'd appreciate you sharing as well. Thanks!
Espresso Restorations
Coffee Geek E-61 Restoration
Insanely Long Water FAQ
Coffee Snobs Portofino Thread
Also, typing "commercial descale" into alt.coffee really gave me a lot of good discussions. I hope you have fun with your refurb work. This has been really rewarding work for me so far and it's been nice to put practical application into a lot of theoretical knowledge I had about machine mechanics. If I didn't love coffee and espresso so much, I could probably be persuaded to take up this work on a more full time basis. :)
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Permalink Reply by Chris on
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Some of the larger stalactites and stalagmites might be knocked off instead of dissolved, neutralizing your acids along the way. Use your own judgment, though...
On the other hand, Snow Drift Farms * will send you powdered citric acid fairly inexpensively. Five pounds for under ten bucks, and a pound takes care of about a year of my normal (not restoration) uses.
*scroll down past the salts, you'll see it...
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