Sciencemadness Discussion Board

Copper plating stainless steel...

evil_lurker - 24-6-2008 at 15:48

I'd like to copper plate the inside of my 304ss moonshine err.. ethanol still with copper to see if it would give some better flavor err... higher proof to the distillate. :D

Did a yahoo search and it didn't turn up much of anything useful... if anyone could give me some pointers on where to look it would be great.

Klute - 24-6-2008 at 16:17

Couldn't the coppe rin some way promote dehydrogeantion to acetaldehdye, and further polymerisations/condensations?

I have a relative distilling his own eau-de-vie, an dhe told me he often got problems with green copper compounds passing in the first fractions, and sometimes contaminating the best fractions (which were obviously re-distilled).

But i guess theses issues can't be that bad as copper still shave been used since eternity, no?

What is supposed to the avanteg of using copper as the still?

Twospoons - 24-6-2008 at 18:53

Copper is supposed to destroy sulphur compounds resulting from fermentation, which produce 'off' flavours in the distillate. The sulphur source is usually residual metabisulphite from sterilizing.

Plating is going to be a lot harder than simply using copper column packing, and possibly less effective. Personally I use knitted copper mesh as the column packing, and I have to say it works extremely well, both as scrubber and packing.

I've even dug out the place I bought it from

http://www.amphora-society.com/equip_1.html

Aren't I nice? :D

[Edited on 25-6-2008 by Twospoons]

smuv - 26-6-2008 at 14:17

I played around with copper plating stainless for simular purposes.

I cleaned the SS piece with IPA and water, then cleaned it electrolytically in a dilute sulfuric acid bath. After cleaning the piece was removed and 2 copper electrodes put in; current was passed through for about a half hour until Cu concentration seemed to come to a steady state (judged by color). Then one of the copper electrodes was removed and the SS piece was connected as the cathode and 5v was passed through (cant think of the current density but it was pretty high). A strike was plated, and then removed by reversing the polarity (to further clean metal surface), then polarity is reversed again to start plating the piece again. The polarity is reversed from time to time for short periods to keep the surface of the piece smoother. The piece is plated in this fashion until you are happy with the thickness.

I dont have in depth notes for this because it worked the first time and many times without any real measurements. You could play around with the sulfuric acid concentration to stop the build up of copper gunk on the SS piece (which probably inhibits the smoothness and current efficiency). In my experience the luster of the peice is crappy, but the Cu certainly adheres well to the piece.

zed - 11-9-2008 at 09:58

The important step is anodizing the stainless steel to activate it. Once activated, plating isn't hard. I remember performing this routine on chromium. It worked well.

I simply used a solution of copper sulfate.

This handy technique, makes it easy to solder to stainless steel or chromium. Normally, it is difficult to solder to stainless steel, and soldering to chromium may prove impossible.

kclo4 - 11-9-2008 at 16:59

That sounds tricky to electroplate iron with copper.
The moment the copper sulfate solution hits the iron wouldn't it precipitate the copper on to the iron and turn the iron into sulfate?

Contrabasso - 12-9-2008 at 12:06

The proof limit is the result of the EtOH/water azeotrope you cannot distill past that.

Plating onto stainless is not easy! Nothing really sticks well.

watson.fawkes - 12-9-2008 at 12:50

Caswell sells a stainless steel activator, which I assume is a nickel salt, since it asks for a nickel electrode. After this strike plate, you'd put on whatever other coating you want.

smuv - 12-9-2008 at 12:54

Very true. You can coat it; and the coating will be fairly scratch resistant, but if you solder to it the joint will be weak. I am sure there is a way of plating a more adherent strike with copper sulfate; but I havn't figured it out (although I havn't searched much patent literature).

Copper onto iron is dead easy...making it shiny is harder, but for the purposes of protecting from oxidation, you can just put the piece into a copper sulfate solution and have the piece be the ANODE, turn on the power for a minute to remove the oxide coating and then let the peice sit; it will have a nice coating of copper in about 30 seconds (I suppose this isnt electroplating really).

watson.fawkes - 12-9-2008 at 13:27

P.S. I saw some reference on the Caswell forums to "Wood's Process". In one old reference, this was a mixture for plating brass with cyanides of copper, zinc, and potassium. In a patent reference, it was apparently nickel chloride. There was another Wood's process involving steel-making, which isn't relevant.

The Caswell solution says you supply your muriatic acid. So I'm guessing their product is just nickel chloride. It works better (again I'm assuming) because the excess chloride ion complexes the nickel.

Contrabasso - 12-9-2008 at 23:17

Onto steel, my old firm used to plate a nickel flash which was very thin, then a copper from a pyrophosphate. This solution plates a leveling copper layer - which tends to fill in small scratches naturally. We then put three separate nickels over that then a chrome.

To get a bright finish the chrome had to have brighteners added these were always odd chemicals that survived for a while in the hot chromic acid but needed regular analysis and top-up.

Ragnarok - 13-9-2008 at 07:10

Quote:
Originally posted by Klute
I have a relative distilling his own eau-de-vie, an dhe told me he often got problems with green copper compounds passing in the first fractions, and sometimes contaminating the best fractions (which were obviously re-distilled).

But i guess theses issues can't be that bad as copper still shave been used since eternity, no?
What is supposed to the avanteg of using copper as the still?

To get rid of the blue coloring, me and my dad used to wash the condenser (made of brass, but it's the same thing) with vinegar (actually a 1:1 mixture of vinegar and water, 'cause we're cheap bastards). You have to do this before each season. Like if you distill 10 batches in a few days, wash it once on day one, rinse and use. If you take long breaks between batches, you have to wash it before each session.

The best way we found is to plug one end of the condenser, put in a liter of washing mixture, plug the other end and rotate it from time to time, empty, rinse and distill.

Another good thing is to add a cup of calcium hydroxide solution to the batch before you distill it, to trap any acids before they can get into your product. The acid problem usually occurs when our plums stay for too long in the barrels we use as fermenters. (details on the technology on YIM, for those interested)

And to keep on topic, copper is the only material used traditionally in such endeavors, and almost every household in the countryside has a still.

zed - 23-10-2008 at 17:33

If you were to read the "Foxfire" books, you might find some tips on distilling beverage alcohol. I say might, because I'm not sure that I actually read about it there.

Seems to me they suggested copper, copper, copper. No solder. All joints sealed by wheat paste.

ElectroWin - 23-7-2013 at 10:41

btw, my understanding of the reason why you want copper is, that some mashes have pectins in them, which the yeast metabolize to methanol; and copper catalyzes the transformation of methanol to formaldehyde, which is easier to separate from the ethanol.

i was able to apply a thin plate of copper to mild steel electrolessly, but my test did not adhere well.

i quote a finishing.com source:
"Plating of stainless steel starts with a Wood's Nickel Strike. The thing is, you can't successfully plate onto tarnish or a passive skin, you must plate on fresh, active metal -- but stainless steel passivates almost instantly. The nickel strike simultaneously dissolves the tarnish while it deposits a fresh layer of nickel plating." -- http://www.finishing.com/153/52.shtml

[Edited on 2013-7-23 by ElectroWin]