Black material inside teflon tube of no-burn steam wand - Page 2

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
Mike-R (original poster)
Posts: 268
Joined: 14 years ago

#11: Post by Mike-R (original poster) »

Mike-R wrote:I just had another thought, I should probably inspect the inside of the copper tubing running from the boiler to the steam valve to see if there is any buildup there.
I just checked the copper tubing and it has the same black residue that pulls out with toothpick (see photo below). So I'm really starting to think that this material is copper corrosion. From what I've read, copper first corrodes to dark brown or black, then to green. So considering the age of my machine, it seems reasonable that I'm in the black stage of oxidation.

If anyone is interested, here are some references to show the color of copper (II) oxide.
https://en.wikipedia.org/wiki/Copper(II)_oxide
https://www.amazon.com/Copper-II-Oxide- ... B07VXR7QYW.

And here is the photo of the toothpick that I used to wipe the inside of my tubing.

Mike-R (original poster)
Posts: 268
Joined: 14 years ago

#12: Post by Mike-R (original poster) »

lagoon wrote:Ok that's a good test, rules out scale. I used to own the Profitec 700 which is essentially the same machine.

Another question, how frequently would you estimate you fully turnover the water in the steam boiler?

Eg: drawing off a full cup of hot water daily would refresh the boiler water every week, which is desirable.

Switch off machine and immediately take off the hot water tip and pull all of the hot water into a white bottomed container. See if there's anything visible.
Thanks for the help and the good advice. I do drain a good bit of water from my boiler every day... about 3/4 cup. I also checked my water in a white porcelain cup and it was clear. It tasted fine too.

BTW, I think I narrowed this down to corrosion in the copper tubing. See my reply #11 in this thread.

Shawn-
Posts: 55
Joined: 1 year ago

#13: Post by Shawn- »

I'm waiting to see if anyone else responds conclusively with the cause of the black buildup.

I recently had to deal with a similar problem.
viewtopic.php?p=957653#p957653

I was not able to determine what it was, but assumed it could have been any combination of minerals, corrosion, and possibly milk casein.
It was very difficult to get the boiler clean to bright copper.

Best of luck. I'm curious to find out what works for you

Mike-R (original poster)
Posts: 268
Joined: 14 years ago

#14: Post by Mike-R (original poster) replying to Shawn- »

Thanks. By process of elimination, I'm pretty convinced now that it's copper (II) oxide as a result of "normal" corrosion in the copper tubing.
  • Copper (II) oxide is a candidate since it is black in color and is one of the common oxides produced when copper corrodes.
  • Milk does not seem like a possible candidate since the black material was also in the copper tubing upstream of the steam valve and considering that my valve is always closed when the machine is cooling down.
  • Scale does not seem like a possible candidate since I use RPavlis water and considering that the material did not dissolve when I placed it in relatively strong citric acid.

Shawn-
Posts: 55
Joined: 1 year ago

#15: Post by Shawn- »

Okay

That sounds consistent with what I dealt with.
I used a pretty strong Phosphoric acid solution to clean my piping, boiler, and group.

I was trepidatious about this but received validation for the process from the local Cimbali dealer that he had used a similar product.

If you have access to the product then...

READ THE SDS SHEET!
USE PPE!
If you don't know what I mean then don't do it.

BTW. The Teflon tube in my La Cimbali HX came out spotless!

Mike-R (original poster)
Posts: 268
Joined: 14 years ago

#16: Post by Mike-R (original poster) »

Shawn- wrote:I used a pretty strong Phosphoric acid solution to clean my piping, boiler, and group.

I was trepidatious about this but received validation for the process from the local Cimbali dealer that he had used a similar product.

If you have access to the product then...

READ THE SDS SHEET!
USE PPE!
If you don't know what I mean then don't do it.

BTW. The Teflon tube in my La Cimbali HX came out spotless!
I'm glad it worked out for you.

Just curious, did you use generic phosphoric acid, or did you buy a pickling solution (i.e., a blend of phosphoric acid and other ingredients for the purpose of removing corrosion from copper/brass)?

Shawn-
Posts: 55
Joined: 1 year ago

#17: Post by Shawn- replying to Mike-R »

I have access to 80% industrial grade phosphoric acid through work.
We use it for producing descaling solutions for draft beer lines and breweries among other things.

I used no additives.
Diluted with tap water.
I wore full PPE while handling the raw material, and gloves and eye protection with the diluted solution.

Mike-R (original poster)
Posts: 268
Joined: 14 years ago

#18: Post by Mike-R (original poster) »

Thanks, Shawn.