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Of course I followed common practice that all soldered parts should go through intensive cleaning and last step is acid bath. I diluted my vinegar (to 2,5%) and left my parts over night. Next morning, around soldered joints it was black stuff. Then I read here on forums, that it is common thing, just too strong acid reaction. Just more cleaning to remove this... But now, I am asking myself it is even smart to be using soft solder, if with contact with acid react badly. So after vinegar cleaning run, my still will be more dirty than before? And I will have to scrub all joints back again. But what the most concern me, what will happen during operating run? Alcohol vapors are acidic and moreover if I have a puke, my joints will be in contact with hot acid and this worry me... Please help.

Hey gover, how did you clean before your soak? Flux is hard to remove and it may just be that the flux reacted with the vinegar. Someone on here will hopefully correct me if I'm wrong, but it's standard practice to use soft solder here. Also just to be certain, you used lead-free plumbing solder, correct? Not leaded or electrical solder?

I am 99,9% that this is not flux and just acid reaction with soft solder. I used lead free Sn-96 Ag-4 silver solder, with water soluble flux intended for hot water plumbing. I have sanded down around joints, soak and wash several times with soap and rinsed. It should not be flux present. I would understand, if it emerge on tight places, where I couldn't wash properly, but it appears everywhere and even on the outside where I spend couple of hours of good scrubbing. Several guys here have reported that to much vinegar on joints, creates black residue.

Soft solder is fine for still construction. Both silver bearing and 95/5 will clean fine. After a vinegar cleaning run, the still will be clean. If not you will need to do it again. Water soluble flux I have never used but paste flux is acid and cleans fine with the acid run. Perhaps post a picture and we can see what this black is. Too much heat can cause this also.

viewtopic.php?f=15&t=44438
This is close to what I saw. And his conclusion was "After some thoughts I decided that this black deposit was a reaction of the tin to the hot glacial acetic acid. Maybe I put too much of the acid for the first run" - PuffingBilly

viewtopic.php?f=2&t=8764&start=15 Here HookLine cleary says: "BTW, soft tin based solders do not seem to like vinegar soaks, leaves a black coating on and around the joins. Only recommend it for cleaning up hard braze joints."

Now I don't have picture to show you. But just from this two threads I am very worried. How can we use something which doesn't "like" acid in still construction. Guy from first link says, that he just cleaned it and start using for moonshine. Here I would ask, is he still producing this black residue, but alcohol vapors are constantly cleaning this stuff from seeing, and cleaning it into jars? If vinegar run leaves black coating, my suspicion is that also alcohol vapors can, but mostly acidic wash could start this effect during runs.

"last step is acid bath"

No, the last step would be a sacrificial run specifically to avoid " alcohol vapors are constantly cleaning this stuff from seeing, and cleaning it into jars"

Something different is going on because I know I've personally done this and not had the same reaction. If I have the chance I can solder a piece of scrap copper tonight and soak it in vinegar overnight to see what I see.

"last step is acid bath"

No, the last step would be a sacrificial run specifically to avoid " alcohol vapors are constantly cleaning this stuff from seeing, and cleaning it into jars"

Yes, of course I know this. I had in my mind, that it is the last cleaning step before putting still together and running vinegar and sacrificial run. This in know fact and I agree with steps. My problem is, that if vinegar or vinegar run produce black coating and from others is known, that acid react with tin, that it could happen or is always happening during normal runs on perfectly cleaned sill (acidic vapors or hot acid puke). And it will be bad, if it is then "cleaned away" in our jar and alcohol vapors are actually erasing evidence of tin residue being created over and over... I am just worried

gover wrote: ↑Wed Nov 20, 2019 9:08 am I diluted my vinegar (to 2,5%) and left my parts over night. Next morning, around soldered joints it was black stuff.

That is the standard reaction for soldered joints soaked in vinegar..

You don't need to soak a soldered joint in vinegar after is has been soldered.. you just need to clean / wash the joint(s) with warn water and soap and a brush as best as can be done.. the rest will clean itself when the vinegar (1 part)/ water (2 parts) run is done.. and then on to a sacrificial run..

Mars

Why did you soak it in vinegar? I have never soaked a soldered joint in acid, be it vinegar, citric acid or anything else.

Step 1 Mechanically clean the joining copper surfaces back to new metal.
Step 2 Apply flux.
Step 3 Assemble the joint.
Step 4 Apply heat and solder.
Step 5 Allow to cool and solidify or quench with a wet rag.
Step 6 Wash in water and mechanically clean again if necessary. (Remove excess solder if it concerns you aesthetically)
Step 7 Vinegar run distillation followed by rinse in running water.
Step 8 Sacrificial ethanol run followed by rinse in running water.

No soaking involved. No black stuff ever encountered. The black you are seeing is most likely the result of a galvanic chemical reaction between the silver and the copper in an acidic bath. Most silver has a small amount of copper impurity and is known to be a cause of tarnishing, exacerbated by acidic environment including human perspiration.

I soak to get rid of any flux and to clean copper. It seams that this was my mistake...

CuWhistle wrote: ↑Wed Nov 20, 2019 1:34 pm
The black you are seeing is most likely the result of a galvanic chemical reaction between the silver and the copper in an acidic bath. Most silver has a small amount of copper impurity and is known to be a cause of tarnishing, exacerbated by acidic environment including human perspiration.

So this reaction is not happening during run, even if it pukes and hot acid is all over the joint? I am just worrying about this

StillerBoy wrote: ↑Wed Nov 20, 2019 1:17 pm the rest will clean itself when the vinegar (1 part)/ water (2 parts) run is done.. and then on to a sacrificial run..

Mars

Could you tell me how strong is your vinegar, because I don't think we have the same and just this dilution by parts isn't enough for me. My is 9%

gover wrote: ↑Wed Nov 20, 2019 1:55 pm Could you tell me how strong is your vinegar, because I don't think we have the same and just this dilution by parts isn't enough for me. My is 9%

It doesn't matter if the vinegar is 5% or 9%, it's vinegar.. and went it diluted to the ratio stated, it will do it's job .. just use it the way it was stated to be diluted, and all will be fine..

Mars

Here is an update to my problem. I followed all recommendations and steps ( soldered, cleaned with water, soap and a lot of scrubbing ) and here is the result on my condenser after vinegar cleaning run (20min of steaming and 10min of condenser on). Before vinegar run it was perfectly shining.
What is this and what is wrong, that others don't get this black stuff deposited around soldered joints?

I cann't see what black stuff you are talking about.. it all looks good to me..

Very nice soldering work done by the way.. I do my cleaning after soldering with hand soap first, then I do a citric acid cleaning.. and many time I don't do the vinegar run, cause it cleaned out well, then on to the sacrificial run..

Mars

Yup , looks perfectly normal .
I’m with Mars regarding cleaning .If I can physically clean it , I skip the vinegar acid run .

BTW , I never soak anything in Vinegar . I use Dilute Sulfuric . 10 minates and its done . I have a bucket I have been using for a few years and its quite blue as it contains a bit of copper sulfate now . Sulfuric acid will deposit this copper onto brass or Solder so when you remove it , it all looks kinda copper plated . You can polish it and it looks like shiny copper but if you use a SS scrubber you can easily remove it and reviel the shiny brass or solder under it ..... with no signs of black .You may prefer the look of that .

Unfortunately this thread in the new distiller reading lounge is a trap for newbies and I fell straight into it.
viewtopic.php?f=46&t=15489

Soaking in vinegar solution overnight was a mistake and I also saw black (probably from the tin) and white (salts from the flux) the next morning. Citric acid cleaned it up nicely, but I'll not repeat the same mistake.

Silver oxide from your solder, especially over heated, dont worry. It's common and normal

Tummydoc wrote: ↑Sat Dec 07, 2019 1:54 pm Silver oxide from your solder, especially over heated, dont worry. It's common and normal

Oh, that makes sense. Especially in my case.

In jewelry its called firescale and firestain. I'd just say it was kissed by a dragon!!

Tummydoc wrote: ↑Sat Dec 07, 2019 1:54 pm Silver oxide from your solder, especially over heated, dont worry. It's common and normal

Ok, I understand that it is normal...And what is correct procedure from here on? Clean this stuff with citric acid or just move to sacrificial run?

gover wrote: ↑Sat Dec 07, 2019 2:10 pm And what is correct procedure from here on? Clean this stuff with citric acid or just move to sacrificial run?

If it was me, I would move on the the sacrificial run.. if you are still in double, do a citric acid cleaning and skip the vinegar run.. as I see nothing wrong with what you have..

Mars