Electronics > Repair
Ultrasonic cleaner size: 10L vs 6L
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SteveThackery:

--- Quote from: mendip_discovery on July 11, 2024, 07:54:26 pm ---
Go big or go home. You will find it easier to use than a small one.


--- End quote ---

Except in this case the bigger cleaner has a lower power-per-litre than the 6L one. I do agree that a larger tank is more useful though.
watchmaker:

--- Quote from: SteveThackery on July 13, 2024, 08:53:40 pm ---
--- Quote from: watchmaker on July 13, 2024, 10:43:19 am ---The brass on the balance becomes very friable and it's action is destroyed.

--- End quote ---

It's also worth pointing out that ammoniated cleaners are popular for (especially) clock repairs, but prolonged immersion of brass in ammonia destroys its integrity.  I've read that it dissolves the zinc from the brass, but I don't know if that bit is true or not.

--- End quote ---

Steve,

Two things about ammonia in cleaning solutions.  It is waste. Excess ammonia means the proportions for making the soap are wrong.  How do I know?  I hold the tradmark to "Historic TImekeepers Ultrasonic Cleaner" as sold by Timesavers and others for two decades.  It was a low ammonia alternative to L&R which forced them to reformulate.

Secondly, ammonia only degrades items like stamped brass.  It was uncovered as a result of brass cartridge failures in the imperial UK army.  The myth about it attacking brass clock parts was created by a guy back in the days of the Syracuse Clocks listserv (1994 to about 2002).  This guy said he had thousands of photomicrographs of SCC failures but when we started calculating man hours and dollars, we pinned him down and he had to admit it was all a thought experiment a al "Sir"Cyril Burt (nature vs nurture twin studies).

But when a lie is repeated often enough....

Look up research on Stress Corrosion Cracking.  Last I looked it all involved drawn or stamped brass in high pressure ammonia environments.

It is really like "personal magnetism" used to explain why a watch performs poorly.

Cavitation is the concern for timepieces.  In fact,for ancient items, I will use ivory soap in very hot water lathered up on a very soft brass bristle brush (feels like a dust brush almost). With this, I can remove fingerprint stains on chronometer plates without harming the spotting (decoration).  But if the prints are acid etched into the brass, that remains.

Gold gilding comes up like new.
SteveThackery:
Thanks, Dewey, that's all really interesting.

One of my British Horological Institute tutors said the same thing about the types of brass affected by ammonia. I have actually damaged one clock part in this way - I accidentally left it immersed in ammoniated clock cleaner for three whole days. The result was to give it a fine frosted look rather than its original shine. I don't know if there were any structural effects - no way of knowing.

As a rule I use aqueous ammoniated L&R on clocks; on watches I use petroleum ether followed by isopropanol - the two different solvents seem to clean up the old lube pretty well. Let me know if you think this is the wrong approach.  :)
jpanhalt:

--- Quote from: SteveThackery on July 14, 2024, 09:24:30 am ---As a rule I use aqueous ammoniated L&R on clocks; on watches I use petroleum ether followed by isopropanol - the two different solvents seem to clean up the old lube pretty well. Let me know if you think this is the wrong approach.  :)

--- End quote ---

I don't do clocks or watches anymore, but I still enjoy working with mechanical parts.  To me, petroleum ether means short chain, non-aromatic hydrocarbons, like hexane.  It is hard to get in the US.  Mineral spirits/paint thinner is similar but much higher boiling.  I use VM&P Naphtha, which is widely available, for fine cleaning in the house and Stoddard or similar for heavy grease in the barn shop (e.g., my parts washer).*   I like them as the increased aromatic content helps with grease and sticky labels.  I sometime wash with an alcohol, acetone, or MEK.   

I came across a reference that may help clear up all of the confusion about names for hydrocarbon solvents: https://cool.culturalheritage.org/waac/wn/wn29/wn29-2/wn29-204.pdf

John

*"Parts Washer" labeled solvents are expensive near me.  That is, compared to the days when when you could go to a a local Mobile station and pump it like gasoline.  Fortunately, there's a well  known dragstrip nearby (Norwalk Speedway).  It's supplier is quite cheap and is willing to sell to me in 5 to 10 gallon amounts.  It is basically Stoddard.   
coppercone2:
oh no not hexane petroleum ether is a very low boiling point solvent designed to boil at the same point as diethyl ether when colliqually refereed to in the USA by most places. It plumes. hexane is a good 30 degrees higher boiling point. I think mine was 30-35C boiling point from Sigma.

Petroleum ether is not known to be nearly as toxic as hexane. Some people might call it zippo fluid, but its available in very high purity as a lab reagent. Hexane has a bad rep. Heptane has a better reputation. Petroleum ether has a much lower point then benzene, which is the most harmful organic solvent in common use, so its safer in that regard since if it won't have benzene in it because of a very big boiling point difference.

The benefit over ether is that it does not absorb water, so it can be stored easier( PE is very non polar). ethyl ether is probobly biologically safer, but possibly more explosive and has strict storage requirements with moisture absorbers and also stabilizers to prevent peroxides from forming (which can explode), but its usually not a problem for cleaning, more like if you distill a bunch of ether out of something and are left with a big glob of ether peroxides in a flask for organic extractions.



Keep in mind though, plumey solvents can accumulate vapors in low spots. You gotta be well ventilated to work with that in large quantities. You could end up with a plume of vapor on the floor that can ignite easily because of its low flash point... i.e. a switch clicking on in a fridge.


Its hard to work with if you wanna wipe something down because it really evaporates fast


This is what I would expect in a USA lab
https://lab.honeywell.com/shop/petroleum-ether-77399
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