Jicafold

So I purchased an ultrasonic cleaner.. The Harbor Freight model. I put 1/2 Simple Green and 1/2 water in the basin. I used Simple Green as I have had a bad experience with Purple Power discoloring aluminum. After 2 cycles, this Suntour Cyclone derailleur came out like this? It had an ok finish before....just dirty. What am I doing wrong? Thank you.

sch

Looks like paint stripping and maybe etching has occurred. This correlates with my experience with SG when I had a leaking gallon
jug of SG and it stripped the paint off the shelf and a tool cabinet below. I would suggest switching to dish
detergent (classically Dawn, but others would work) instead in the future for degreasing and cleaning, at a
concentration more in the 2-8% detergent to water range. I use SG straight to clean chains and am happy
with the result using a Park type chain cleaner and 100% SG first pass, ~50% second pass and then water
rinse til clear.

FBinNY 

I suspect that you're seeing the effects of mixing metals in an ionic solution. Essentially, you made a battery and shorted it out, with the ultrasonic acting to speed things up.

I've used powerful industrial ultrasonic for years and make it a rule to avoid mixing metals, or if necessary, to use non-ionic solutions, ie. petroleum based solvents.

For safety and best results read up on the "double boiler" method for using various solvents in your ultrasonic cleaner. I usually use glass loaf pans (with or without covers) which rest on the top. Besides the freedom to use different solvents, it makes cleanup that much easier.

Jicafold

Ok. Chemistry was never my best subject. I preferred history. You always have good advice FB. So do not mix aluminum and steel? Do you feel that using the dish soap as the other respondent said would negate that problem?

Iride01 

Did this just happen in a short time? Or was it hours or even days? I usually see that kind of damage on parts that were left soaking for a time in a water based solution of various cleaners. Especially any that are ammonia based.

I'd use mineral spirits. If it can't be put in the ultra-sonic cleaner, then I'd toss the ultra-sonic cleaner and just use the mineral spirits. Empty the used mineral spirits into a jug and let it sit till you need it the next time and much of the crud will have settled to the bottom and you can then decant the clean stuff to reuse.

FBinNY 

Obviously, a milder solution will do less damage, but may not clean well either. It's been asked, and is a valid point--- How long were the parts in that bath? Typically ultrasonic times are minutes, with 30minutes being on the long side. Keep in min, that problems like this are about time and chemistry with the ultrasonic speeding things up. What might take 24 hours in a bath happens in minutes with the mechanical action of an ultrasonic.

One last point. My earlier post assumed bare or anodized parts. If they were painted, then you shouldn't be surprised that your solution acted like a paint stripper. I've often had to clean painted machine parts, and even those with industrial paint and intended for use in tough conditions suffered paint damage from blistering to complete stripping.

Bill Kapaun

I'll put the cleaning solution in an old "tall enough" plastic drinking glass or a thin plastic sandwich meat tub, depending on the part(s) and place/float in the tub filled to the appropriate height of tap water. It keeps the tub clean.
I DON'T use any flammable types of cleaners. Just not a good idea to heat/vaporize flammable stuff indoors.
Screw lid containers could be used for reused cleaners.

maddog34

the ultrasonic cleaner machine had nothing to do with that ugly mess.

simple green even dulls baked on factory gloss paint jobs... i quit using that crap after it dulled up several brand new mid-mowers....

try using dawn dish soap next time.

so.. how long did you leave that der. in the bath, anyway?
did you try a rag, a brush, and some penetrating oil before you ruined your derailleur?
not only would it work faster, it would be lubed at the same time.

i left a brand new ultrasonic cleaner under the workbench after wasting hours trying to get it to clean small carb parts.. it was bought by the manager for that purpose because a salesman said they worked great... it never got a single carb as clean as PB Blaster, a few squirts of Gumout carb cleaner, and plunging with a jet cleaner.
Manager: "leave it in overnight, see if that works!"... i had been following the owner manual suggestions prior to that.... it was a fancy "Industrial Sonic Cleaner".and we were using their solution....
i removed a dark gray carb with crusted fuel still clogging the fuel orifices, and several pits in it's surfaces.... that overpriced soap shaker is still under that same bench, last time i visited that shop. Loren paid over $500 for it.

next cleaning, grab a rag, some PB, and a brush or two... save time and cash!
a few blasts of high pressure air will clean the hidden crevices....

afm199

I use my cleaner for cleaning cassettes and chains, never derailleurs. If there's gunked up stuff on the derailleur, hit it with some brake cleaner, and promptly spray it down with WD40, wipe it off, and lube the pivots points. If your cassettes have anodized color, it will be ruined and stripped.

These days I only use paint thinner for a cleaning medium. Simple green and other "organic" cleaners all contain acids, in the instance of Simple Green, it's hydrochloric acid. Along with a bunch of acidic esters. If you're going to use simple green, don't soak anything in it, and always wash it in plenty of water.

Paint thinner is flammable and precautions should be taken. It's best to decant it into closed containers after use, it is volatile enough to create a hazardous situation if open containers are left around.

etherhuffer

I degrease with a solvent first, mineral spirits. Then go to Dawn dish soap. It's a pretty good soap for greasy stuff. Then spray down with a light lubricant at the end of the cleaning. As others noted, mixed metals are able to react with each other in the presence of a conductive solution. Chalk it up to learning and live happily with the thought that vintage parts are far far less than a new bike!

Jicafold

I had the parts in the bath for two 5 minute cycles. Another thing....I had aluminum brake calipers in there too, with steel springs. They were fine.

grumpus

Aluminium is a highly reactive metal, oxidising rapidly on contact with oxygen in the atmosphere. But that oxide forms a hard impermeable and unreactive layer which protects the aluminium from further oxidation. Aluminium also dissolves in water when stripped of its protective layer - it seems the combination of ultrasound and chemicals that you used has broken down the oxide layer allowing the underlying surface to dissolve. Fortunately it looks very superficial, so it should polish up nicely.

FBinNY 

You need to understand that the ultrasonic is not the issue. The chemical bath is what did the damage, with the ultrasonic only speeding things up. I'm not familiar with that RD, but a key factor is how it was finished, ie. polished bare metal, anodized, or painted. Also read the label on the solvent carefully for any warnings about metals, paints or otherwise. FWIW diluting it by half wouldn't have made any difference.

Hondo6

FWIW: based on pix posted, the OPs derailleur seems to be a Cyclone Mark II, probably the 3500 (cage looks too short to be the GT 3700). Disraeli Gears site owner Mike Sweatman indicates that Suntour RD was anodized but had printed branding.

Edited to add: also FWIW, Simple Green is somewhat alkaline (pH given as 8.5 to 9.5 in various sources). Not sure it's a particularly good choice for use on aluminum parts (anodized or otherwise) in an ultrasonic cleaner, even at 50/50 dilution.