the question has been raised.
Reels are loaded with gunk and corrosion - usually 70 to 80 years' worth by the time I get them. They're made out of aluminum, brass and steel, painted, anodized, or bare. Lubricants oxidize, releasing acids (or caustic in the case of lithium) form tars and waxes and eventually turn into polymers. Limestone residues from chalk streams are corrosive to aluminum.
Reels have it tough. I've never taken before photos, and I've had some nasty ones, but most of you have seen some of my after photos. Here's what I do. (credit to Richard Thomann who gave me this procedure 10 year ago, though, I've added my caveats, touches and insight from my experience working with it)
1) Take the reel down as far as you feel comfortable.
2) Wipe everything down with paper towels or q-tips and whatever you can to remove the loose debris and old lubricant.
3) Vinegar-water bath. This is generally four parts warm water to one part vinegar. Temperature, time and vinegar content can all go up (up to 3 hours) if you reel is all brass. (NOT painted brass - use only soapy water rinses and brushes on painted brass, because the hydrogen generated in any immersion solution will blow the paint right off.)
some basic guidelines - 30 to 45 minutes for painted reels, or rubber side plates and handles (bakelite is impervious)
wouldn't go past 1 hour for lead finished alloy fly reels
2 hours for plated brass
3 hours for bare brass or German silver
Generally, we're looking at finger-warm solution for about an hour or less. On a painted aluminum reel or lead finished reel, you might want to keep it down to a half-hour. Although, lead finish is usually more tolerant than paint, so you can push to the full hour if it needs it. And take it out when its visibly clean. Take a soft tooth brush to the debris every 10-15 minutes. This solution should do the bulk of your cleaning. If you have tenacious crud, rusted steel, dealloyed brass (looks pink) you may want to push it a little longer, but balance it against the visible effects on your finish. Rub out the insides of bushings with q-tips or twisted up paper towel.
Rinse well in lukewarm water.
4) dilute soap bath - very dilute. Alkalis cause corrosion of aluminum. Ammonia causes cracking of brass. Not to alarm you, but you're simply using this bath to wet and remove the tar remnants that were broken up by the vinegar, and to neutralize residual vinegar. Again use the soft toothbrush to break up any residues.
5) Final rinse - very thorough cold-water rinse here. Be careful of the sink rinsing off your tiny parts.
6) Air dry - overnight is good.
7) Rub with a wax or silicone guncloth. This is also a good time to put on a coating of Butcher's Bowling Alley Wax if you want to do that kind of thing.
8 ) Lube and reassemble - use Zebco Quantum Hot Sauce - the good stuff.
Hot Sauce Grease on drag gears, and on worn and wobbly spindles. Hot Sauce Lube (light oil) on spindles/bushings, handle spindles, pawl stanchions, bearings, drag blocks and threads.
Magnesium reels - Marryat, Battenkill MkIII - exposed magnesium appears to react vigorously with vinegar, so it's probably wisest to bypass soaking in solutions and use Boeshield for cleaning.
Solvents - acetone is for removing paint and plastic handles - be very careful. Yes, it removes tars also. Be very careful.
One application for denatured alcohol is removing old line varnish from inside a spool. It will usually come out with a good swipe, but try to avoid drips, keep it away from handles, follow quickly with a dry swab and even limit exposure to the paint.
oxidizers/colorants/patinating agents with their steps and rinses would fit between steps 6 and 7 above, but this is real art that I'm going to dodge here.
I'm going to mostly stay away from this, because I usually quit at wax.
But OK, I keep Pol metal polish around, and always have "Miracle" lemon-oil polishing cloths.
I lightly and quickly rub down my rods with Miracle polishing cloths to keep the calcium buildup down, and chase that with a chamois.
They are also very useful for rubbing out rust on steel - there you go Cameron.
more discussion can be found on this ORCA pageorca-online.org/reel-talk/viewforum.php?f=6
Hope this helps,
p.s. here's the goal