Kiwi Stillers cleaning run tutorial.

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Kiwi Stillers cleaning run tutorial.

Postby MacStill » Fri Sep 07, 2012 10:31 am

How do I clean my new still?
This one has been cropping up quite often recently. When you build a still, it will generally result in some rather dirty metal. There will be a lot of oxidised crap all over it, as well as flux, etc. To deal with this and make it safe, we perform a 'cleaning run' (or sometimes two). There is no 'right' way to make sure a still is clean, this is just one option that I've written up to clear up some confusion. I'll only talk about the inside of the still, and I'll leave Olddog to tell you how to make the outside shine if you're so inclined (optional extra, but damn his stills look good). This guide will attempt to err WAY on the side of caution, and detail a very thorough cleaning process. Obviously, it's going to be a little on the vague side, considering the differences in stills you could build.

1 - Soak and Scrub
A really good way to start is to soak any parts small enough in a weak acid solution - I'd use dilute vinegar, which we can reuse for the next step. soak it for a good few hours, or overnight. This is really an optional step, but is a nice idea for things like coils. You can augment it by giving the insides a bit of a scrub as well with a kitchen scourer (don't use your packing for this ). Keep the vinegar solution.

2 - Vinegar Cleaning Run
Next, chuck the 50/50 water & vinegar solution into your boiler, attach the still head, and fire it up. I personally like the idea of blasting the still and condenser with acidic steam - the problem if you don't run steam through it is that some areas (like the top of a liebig condenser) may be untouched in normal, condenser-on operation. Of course, as we're only boiling a vinegar and water charge, there is no fire danger - but there is still vapour being generated, so this is a good time to double check that your still is always open at some point to the atmosphere. Of course, normal caution is needed with hot steam, don't scald yourself. If your column has packing, it isn't necessary to have it in at this stage.

Special consideration for VM: you might struggle to get steam out the takeoff. If this is the case, check your valve is open, then roughly cap your still, check again that your valve is open, then check a third time - this is because we're breaking the cardinal rule here, if the valve was shut, the still could build pressure. When I had to roughly cap my VM (for this purpose), I got an offcut of 4x2, and made a circle of dough paste, and sat it on top - this was enough, it doesn't need to be perfect.

After steaming it for 20 minutes or so, turn on the condenser(s), pour water into the worm bucket, whatever it is that will return your still to normal condensing operation. Check that the condenser is knocking down vapour. A reflux condenser may struggle to knock down this vapour, don't worry about that at this stage, it's a lot easier to condense ethanol / water mix. Run with the condenser(s) on for 20 minutes or so. This is a really good time to get a (glass!) mirror, and check for vapour leaks in any seals and solder joins, brazing, etc... The mirror will fog up if held up to a leak.

Shut down and ditch your vinegar.

Give everything a comprehensive rinse out with water. Most of your still should be pretty shiny on the inside by now. If there are visual patches of flux and crap still in there, go back and do some more soaking and scrubbing before you continue.

3 - Ethanol Cleaning Run
To be completely thorough, we should do an alcohol cleaning run as well. Use any old wash, pretty much whatever you can make the cheapest and easiest. Alternatively, you could chuck in some cheap box wine or something (avoid beer - hard to get the hop oils out afterwards), pretty much any source of ethanol you like. DO NOT use denatured alcohol for this (never put that through your still).

This second cleaning run can double as a practice of still operation. If it's a reflux head, you can put the packing in for this one. Do not repeat the steaming step we did with the vinegar run, as the ethanol vapour is of course flammable, and heavy. Just run the wash in the normal fashion for your design, and have a play around with heat / cooling to get the hang of it. See how the ABV changes. If it's a reflux, play around with the reflux management, see how things respond to your actions. You get the idea.

Don't treat this as drinkable, but do keep it, clearly labeled as cleaning run alcohol - you can use this for your next build. Trust me, there'll be others

Right, that's it, the three step process to ensure you have a safely clean still to begin your hobby with
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