So I build myself a fractionning column from junk copper I found here and there and try to get it super clean.
The copper I scored was dirty ... super dirty, oxydized.
I scrub and scrub again with citric acid and salt to get it looks ok, but is ok, OK?
I did 2 run with 6L vinegar 5%, the vinegar was soooo dirty blueish grey and the coppre was full of dirty dripping traces. I scratched and rubbed with a scrubber and then the copper looked super clean again.
Yesterday I run sucessfully 6L of cheap wine. Sucess! 400ml of 94% came out clear and ok smell
but the inside of the still looked so dirty again (see picture)... some black traces...Here are my concern:
- when cleaning the bottom of the column after removing the packing, the towel was copper color!
- above the waterline in the copper heater, there are some traces / dripping that are black. Under the water line copper looks like new
- some of my dirty dirty silver-welding look still weird, blackish
Here are my the possible cause:
- I'm too carefull (the ethanol comes out perfectly transparent) and a copper still can oxydize a bit > just move on
- the copper was too dirty > extra cleaning run
- the copper was to dirty and needed to be cleaned better before assembly.... what's next??
- i welded like... a beginner... too much flux, too much welding... resulting in a lot of stuff to be cleaned > extra cleaning run
- the cork seal between the column and the boiler is creating this weird black traces...
- other idea?
Is it normal? Am i trying to be too clean?
How does the inside of your copper still looks like?