Ultrasonic Cleaning Solutions- Opinions

We are using Aqua-2000 in our ultrasonics to clean pieces that are sterling silver, 10K Golds, 14K Golds. Aside from the phenomenal expense of the Aqua-2000, we have problems where sometimes the flat polished areas start to look hazy or cloudy. Examination with a loupe shows a kind of micro-etching across the surface. The brushed surface on the back of pieces doesn’t show any issues. Golds are not affected at all, nor is brass. It’s only on the sterling silver. Our metal pieces are manufactured for us by a couple different companies. We laser engrave fingerprints and inscriptions, then polish and plate (if needed).

I’m looking at other cleaners to test, both for economy and eliminate the pitting problem. We have several Elma ultrasonics going and process 400 or more pieces per day (across the machines). The machines are emptied and cleaned every shift. I’d like to know what other jewelers think about various solutions out there. It has to be non-ammoniated and environmentally friendly (most that I look at are).

Some cleaners I’m considering are:

  • Magic Green
  • BCR and/or BCR+
  • Stuller Supersonic
  • Luxor Clean
  • Sharper Tek
  • Ultra-CR

Thank you,

Ruthanne Robertson
R&D Bench Jeweler, Legacytouch Inc.

Hi Ruthanne,

Omg, I had this same dilemma awhile back, in addition to pits and subsurface inclusions…

question…are your the hazy cloudy areas around the edges…?

Long painful story short, I found two different solutions to this problem…that in itself is bizarre, but such was my life…

1a) in my case, I was ultrasonic cleaning only 20-50 pieces per day…as I moved thru the polishing process, progressively more abrasive compounds get washed off (and not even that much because I remove most before I get to the ultrasonic)…, and subsequently remain suspended in the ultrasonic solution, which in conjunction with the cavitation action of the ultrasonic…microscopically abrades the mirror finish…

because this sounded like the most obvious cause, my solution to this was to have two (2) ultrasonics…one for pre-polish compounds, and one for final polish compounds, to keep the grits separated, and to change the solution when I could no longer see thru it, or daily, which ever came first.

1b) I also replaced both of my ultrasonics, in the event that they were not cavitating properly, possibly too aggressively…

1c) I also tried many different ultrasonic solution…my friend who also did mirror polish on flat sterling silver suggested BCR, and I found that I liked it the best…

  1. weirdly, I (also? still kind of a traumatic mystery) I believe that my finger oils played a part in this white haze/ cloudiness…after polishing the front of the charm, I would hit the back of the charm real quick to remove the compound built up from my leather finger cots,(not all of my fingers were in leather finger cots)…(I also used a piece of leather thong thru the jumpring to help hold the piece)…

anyway, one of the many jewelry supplier metals departments that I called speculated that it might be due to the oils on my fingers…and suggested that I get cotton gloves, cut the tips off, and use them as quick release finger cots…this worked…

Good luck and please please let me/ us know what you discover!

Julie

I just bought a new ultrasonic that I have yet to use, so I can’t pass on much about it. It is a Best Built from Otto Frei. Regarding holding small objects like charms, earrings and pendants that may have a small jump ring or open area. I screw a small hook into the end of a piece of dowel and pass the hook through the jump ring or whatever I can to hold and control the piece when I am polishing. I also use woven cotton gloves that I buy in small bulk packages. They aren’t left or right, so you can turn them around when you wear a hole in them. There is the whole discussion about wearing gloves when you polish. If I didn’t, I would constantly be experiencing very painful burns. I have equipped my polisher with a dead man switch that kills power to the motor as soon as I step off of it should I experience some sort of glove related or other mishap while polishing. Polishing is hard work and the first chore that my father set me to when he agreed to teach me how to make jewelry…Rob

Hey Rob,

Since we polish heavily and all day long, finger protection is imperative. We use variations, depending on jeweler polishing style and preference. The base for everyone is a pair of thin nitrile gloves. The components of the polishing compounds can cause dermatitis problems, especially if you polish all day. Most of us use combinations of alligator tape and cotton finger cots and a tough knit glove that is partially coated in rubber. The nitrile gloves and tough gloves are required PPE, the other is personal preference.

To hold most pieces, we use a long hook (3" total length) made from 12g copper wire. The hook end is deep (about an inch) so pieces don’t fall off while working. The remainder is bent into a sort of handle that fits well in the palm and fingers. Since we polish so hard, sturdy hooks are needed.

We polish very fast and only use one compound (Picasso Blue). It takes about 3-5 minutes for a ring (no stones), 45 seconds for a 1/2" charm and about 1.5 minutes for a 1" pendant. I had to “relearn” how to polish when I started even though I was teaching Jewelry and Metals at a College. It’s unconventional, but so much faster and easier. It’s changed how I polish whether it’s one or dozens of items.

As far as the cleaning issues go, the haze or cloudiness we see is not so much discoloration as the finish looks cloudy. I describe the pieces as having a mottled look. At an angle, the surface appears to be intact (naked eye). But if you look with a 10X loupe or better, the tiny pits are apparent. We have had milky discoloration on pieces. This is almost always when I piece is removed from the ultrasonic, but not rinsed and steamed immediately. Usually the basket holding pieces has been removed and the pieces are sitting in the open air. I know the issue isn’t from particulate in dirty solution hitting pieces because it can also happen with fresh solution. It happens at different concentrations also.

Since we only use one compound (most of the time), there are no coarser particles slamming around in the solution. If we changed solution when you can’t see through it, we would be dumping and remixing after about an hour or two. It’s just not feasible to do that in a production environment. We do change solution every day and clean the tanks.

We also do a quick hit on the front at the end of polishing to make sure there aren’t streaks of compound. Leathers are particularly problematic because the compound gets embedded in crevices and is really hard to remove. About the only time anyone wears leather is when polishing trays of display rings (12 per tray). If streaks of compound remain on the surface, the finish will be dull in those areas after cleaning. Since there is a significant build up of compound on the finger cots, alligator tape and gloves, we try to release pieces off the hook without touching the surface too much.

I am going to test Magic Green, which I am ordering. We also have some Rio Jewelry Cleaner Concentrate and some Rio Rapid Cleaner in the chemicals cabinet. I’ll try those as well. I’ll be testing time in the solutions, since that may be a factor. The other thing I have to test is whether any of these cleaners leave a residue that will complicate plating. I do believe some of the issues I am solving are due to the composition OR manufacturing of the metal sheet our supplier uses. Some of the problems don’t appear on other pieces, so that may also factor in. However, that would be a big fix and take months to resolve. If I can find the right cleaner, we can save that effort for later.

Metal- always mysteries to unravel. Always new things to learn.

Ruthanne Robertson

R&D Bench Jeweler, Legacytouch Inc.

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Ruthanne…Thanks for your reply. There is a lot to digest. I am just a one man show working at a hobby business. I don’t have to worry about what and when I get it done. That being said, part of the hobby has always been to set my shop up to be a production shop should the need arise. Mercifully it never did and I was able to stay well employed while I made jewelry in my spare time. Now, having been retired for 13 years, I just putter. I have been able to explore new mediums, try new tools and create new designs. I guess that I am an R&D shop. I have always wanted to tour production shops and manufacturing jewelers to see how they go about making jewelry. Living in the sticks, there is little opportunity to do this. I do visit all the local jewelry stores to see what they sell and how they operate. I am struck by how many don’t have a bench jeweler on site or if they do, it is just for show. I did visit a small independent shop yesterday where I could tell by the work and condition of the shop that a lot of what was for sale was made locally in the shop by the owner. I have had fun making and occasionally selling my jewelry for nearly 50 years. I am, however, very happy that I never had to make a living doing it. Thanks…Rob

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Hi ruthanne,

Thanks for the tip on the hook holder and leather finger cots!

One other thing that was related to my sterling silver, mirror finish, surface trauma, was subsurface pits and inclusions the were near the surface of the metal, due to what happens when sterling silver ingots solidifies, I have discovered from the Brehpol book!..

I was hard headed and did not clearly understand when quite a few orchid members told me that “they just sand the surface first”…I was like " I am" (as I cried in frustration!)

(i was just not sanding enough, as the surface of the clean stamped discs was rather…“nice”…)

My long over-due epiphany came when talking to someone in a production department at…I forget which company…where she said “ok, let me tell you exactly what we do, from start to finish, for flat discs…” (she was amazing!)…they had flat disc jigs made, sort of like the coin slots for old-fashioned bubblegum machines…where they put the disc in the custom fit depression, and hit the pieces on sanding wheels, to take off that initial surface layer where I believe the oxides, etc, congregate on the the disc…flip the disc and repeat…etc…

her help, along with finding the paragraph in the Brehpol book about how metal solidifies, made my brain work properly…“I gotta sand that crud layer off first!” I was told that older metal fabrication processes included planing the surface of the metal before rolling, which I do believe probably removed the crud, and reduced the subsurface pitting and inclusions that plagued (me at least)…now I just buy thicker sheet to allow for the surface sanding…

(I apologize in advance for the the above expressed in my brief layman’s terms)

Julie

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Hi Julie,

It is true that if an ingot is not worked sufficiently through some type of impact (hammer) or milling (rolling), the structure of the metal will be poor. I’ve noticed that silver sheet I’ve purchased in more recent years is not of the same quality as what I used to get years ago. It may be some refiners are cutting corners by not milling the sheets as much. It’s the process of annealing and work hardening repeatedly that consolidates the structure of the metal.

The oxides on silver are of copper origin. The silver isn’t going to oxidize at all, but the copper in the alloy migrates to the surface either over time or when exposed to oxygen and heat. Usually there is a layer of black copper oxide on the surface, which the pickle removes. Below that we often find a layer of pure silver, if that stays intact, the surface won’t oxidize. But beneath that layer is something jewelers call “fire scale”, which is another copper oxide (it tends to look purple). The annoying thing about fire scale is the layers can go pretty deep. Repeated heating (soldering for example) with inadequate protection from oxygen produces this oxide. Of course it makes itself known in the final stages of finishing. Sanding exposes these layers and sometimes you have to sand pretty deep to remove it.

There are 2 solutions used to disguise it. The traditional method, always avaliable, is called “Depletion Gilding”. The piece is heated to just at annealing temperature and pickled repeatedly. Eventually all that is visible is fine white silver. The process is repeated a number of times to make a thicker layer and then the piece can be burnished with a fine brass brush and soapy water. It could also be tumbled with steel shot. The other way, which is quicker, is to plate the piece with either Rhodium, Palladium or Platinum. This has the added advantage of preventing future oxidizing because Palladium or Platinum provide a barrier layer the copper can’t migrate through.

When it comes to sanding, the trick is to not start with a grit coarser than necessary. With experience you can determine if you need to start with 180 or 240, etc. Then, making sure to remove all marks with the first grit, the next grit is sanded across at an angle or perpendicular. This way you can always tell if you’ve removed the previous grit. Some people go to 800 before a final polish, I’m comfortable with 400. If you’re doing some sort of brushed finish, all the sanding can be parallel to each other and won’t show.

My students never believed they needed to sand well before a final polish and would try to cut corners. Of course I could always tell where steps got skipped. Your eye/brain get trained and after awhile you can see the tiniest flaws that the average person won’t. A lot of it is being alert to slight changes in value on the surface. I’ve had cataract surgery which leaves me frustrated at times, but I find that I can still recognize flaws on surfaces fairly easily. This is the brain doing it’s work to decipher the marks.

Good Luck with your adventures. Brehpol is a great book. Another must-have is Oppi Untrecht’s “Jewelry, Concepts and Technology”. This is like a jeweler’s encyclopedia. Tim McCreight’s “Complete Metalsmith” is also a staple. Those 3 books have always been my go to or starting point for information. Of course there are loads of others, especially specific techniques and I can’t seem to bypass a good jewelry or metals book.

Ruthanne

Hi Ruthannie
As a hobbyist I witnessed your problem with Sterling and also Alpaca, I re-polished the piece and end of the story. Back in the 70s I witnessed first hand a hospital cleaning surgery tools to find the new ultrasonic cleaner peeling off the plating of certain items, this fact is disclosed by manufacturers of ultrasonic cleaning machines. For many years I worked close to a high precision stamping operation, parts were first degreased chemically and then in small batches ultrasonically cleaned for a few minutes. In other words the ultrasonic may not be a replacement for degreasing first. My gut feeling is that parts should not touch each other during cleaning, hanging like plating racks and also not staying very long in the same place of the tank to avoid high power zones for too long.

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Are these pieces cast or struck? I ask because in cast items, even after achieving a gloss finish, a run through the ultrasonic can cause some micro porosity in the otherwise beautifully cast metal to become suddenly visible. Not every piece, just some. Stuck item have a much tighter grain structure. This is, usually fixed with a quick gloss and a VERY short dip in the ultra sonic.

In general, duration in the 'sonic is crucial to watch. Here, there are 2 cleaning cycles. the first is after cut down - and you can live that in the 'sonic forever, if you wish. The second, after glossing, is a brief dunking to clean the minor amount of compound remaining.

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