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During the run, I noticed weird discoloration in my sight glass, I stop the run and I looked. Top of my sight glass was dark brawn like someone painted whole ss. Then I noticed the same thing on my copper ferrule, it is just like someone painted small dark brown ring on the bottom of my ferrule. I don't know what it could be. It can not be puke, because the bottom of my sight glass doesn't have this brown stuff but instead weird blue discoloration. For me the only reason can be melting of ptfe tape, which I have put it around silicone gasket inside the sight glass. I had this weird blue discoloration in previous runs but not the brown stuff. The only different thing I have done in this run is that I heated my boiler very very slowly (maybe to slowly) and this part above boiler, where I have sight glass, was hot for a long time before vapors reached the top of the column, maybe 1h... This stuff is not getting easy of ss and it you must scraped it off. It is possible that ptfe melts inside during run? What to do now?

No, the melting temperature if PTFE is 327C so that's not possible in still operation. Based on the colors you mentioned (blue) it sounds more like you pulled some oxidation from the copper ferrule. Else it's not pfte, in which case clean and replace.

What were you running? Did you add anything to the boiler for the run?

I know that PTFE has that melting point, but I really don't have another explanation for painted like residue on the top of my sight glass and the bottom of my ferrule. I had this blue discoloration in one previous run and I don't think that this two things have the same reason. The only thing I changed from previous runs, that before I had just ptfe tape around glass to make a seal and now I put in the original silicon gasket and wrap it with ptfe tape.

I was running all grain wash + faints from one stripping run and run it like spirit run (1.5 method)...

Have you done a cleaning run with vinegar it citric acid recent?

I cleaned it around 6 stripping runs back... I out all copper parts into citric bath for few minutes.

gover wrote: ↑Wed May 13, 2020 6:59 am I out all copper parts into citric bath for few minutes.

Did you neutralize the copper with baking soda after the citric bath..

Copper needs to be neutralize whenever citric acid is used to clean the copper with..

Mars

No I didn't... But I don't know how could not neutralizing copper could play a role here. So what is this brown stuff? It is just around 3 inch in length and it is not all across the pipe. So I don't thing that cleaning or not cleaning properly is the reason...

Not neutralizing the acidity will lead to blue corrosion and blue distillate. Not sure about the brown though. Unless the distillate made it's way through the gaps in the ptfe tape and into that silicone gasket and degraded it.

Distillate was normal until I stopped the run. And I talking about blue discoloration of ss in sight glass, like when you heat a metal and you see blue and red spots... Silicone gasket was not degraded and I had 2 layers of ptfe around it and first layer was clean and in perfect condition. It is really strange thing what happened...

gover wrote: ↑Wed May 13, 2020 10:55 am Distillate was normal until I stopped the run. And I talking about blue discoloration of ss in sight glass, like when you heat a metal and you see blue and red spots...

That's a description of fusel oils.

Ok, but my main question was, what is the brawn stuff on my sight glass and ferrule. This worry me, because I don't know what it is.

Smell it, taste it.

Just sounds like freed copper patina to me.

I don't know why patina would left almost perfect 1/4" black ring on my ferrule. I would understand some random discoloration, but this...

Any chance you could take a picture?

All three parts were clean before this run.

fusel oils

So this is normal and why I wasn't seeing this before?

Depends on lots of things... ferment, the final PH of the boiler charge and the running conditions; I typically see them accompanying tails, so run length. I personally just clean it and go, or don't, it's mostly cosmetic in my opinion. Up to you.

Agree with Expat.. I've experience the same.. just clean it and move on..

What was the run on.. long runs of stripping wine will do it for me..

Mars

It is strange, because I was just getting harts and abv was above 50% when I saw this...