As we all know watch cleaning fluids and rinses are expensive. I was contemplating a way to extend the life of the fluids I use and I think I hit upon a good idea.
When your fluids start to get old and dirty try straining them through a new paper coffee filter.
I placed a coffee filter in side of a glass jar such as a ball caning jar and poured the fluids through it. Next clean the jar that you use in the machine, ammona worked great for me. Wash and dry the jar, ( a little hint here, don't use your wife's good dish towel to dry with) Place another clean filter into the jar used with the cleaning machine and pour the fluid back into the clean jar. What a difference. The fluids do not break down like car oil so I should be able to get a few more miles out of it.
What do you think!

It's a good idea and Zenith solutions even mentions to do it on their page for Formula 67: Zenith Solutions.
"After several cleanings the floating debris can be filtered through a strainer and the cleaner can be used again with no change in cleaning power."

I'm not sure about filtering the rinse because of dilution or contamination with the cleaner.
Mike

I use an large ultrasonic (It was free for me, so bear with me on why I use such a large one) and it takes almost a gallon to fill the beast up enough to submerge parts in, so I will have to try the filtering method. I might try it this week as it is getting dirty enough that I can't see the parts anymore and I was able to see the bottom for quite a long time when I first filled it. I use very minimal rinse (small container) and would agree with Mike that I can afford to just change it out every so many watches (about 20-30 watches). I will say that I do let the rinse solution sit for a couple days and skim the clear, good part off the top. I do this about halfway thru its lifespan to help keep the matter that happens to make it to the rinse cycle off future watches running thru it.

In a large ultrasonic, if you have a basket that can suspend items off the bottom, you can fill the cleaner with water and use beakers immersed in it for your cleaning solutions and rinse. The ultrasonic energy will transfer through and you can save on the amount of fluids used.
Ultrasonic cleaners, especially those with heaters, should not be run below the recommended fluid level which is usually an inch or so below the top. Also, they shouldn't have anything placed directly on the bottom. I think this is to prevent the ultrasonic energy from being reflected back and overheat or damage the transducer.
Mike

I have a heated ultrasonic and just use hot tap water, vinegar and a drop or two of Dawn Dish detergent. It does a great job. I have added chemicals made for ultrasonic cleaning but have not found a difference in the end result except for $$$$ spent on the chemical. I am on a well and the water is soft. When I change out the fluid the only cost is the vinegar and it's cheap. I put a black silver Mercury dime in and it came out like new after two trips through. Watches act the same way only I just use a 20 min cycle. (1.75 liters of water, 2 teaspoons of vinegar and three drops of Dawn) It's a two liter machine.
Patrick 1616

When I first transferred over to Zenith cleaning fluids I read about the filtering using coffee filters etc and experimented with it. I use a fully automatic 4 jar system each jar is filled approx half full about a quart of fluid, 2 clean and 2 rinse (1 gallon per fluid change), filtering does visually clean the fluid and remove the larger visual solids that are suspended in the fluid. There are several problems as Michael says is the first rinse is contaminated with cleaning fluid, filters shed tiny hairs from filters that get onto the parts and the cleaning quality of the parts finish is lessened, including droplets appear on the parts from fluid breakdown. Doing this professionally is different from home hobby use, I need to make sure I 100% replace the fluids before they start to fail and do the best job I can each time, for the number of watches you can clean the cost is very low if you consider the cost of any other hobby, ( I shoot as a hobby and can quickly use the equivalent of several gallons of cleaning fluid in a short morning) of course the clean and rinse are just part of a whole series of cleaning operations that go into the service, preparation and pre cleaning will extend the life of the fluids greatly. I keep my old fluids they are great for cleaning all kind parts in the garage and when completely dirty I light the garden fires!. I will also plan my work cycle around fluid changes.

Chris, thanks for the tip on the small fibers that come off the filters. Something I did not think about.
Now I am wondering what is in my morning coffee! Than again fiber is good for you!

Maybe the cheap filters I used or the chemicals breaking it down, even if you used a better filter method the fluid has done its work and weekend in its ability to clean and retain the dirt, oils etc. Each jar is cross contaminated again for home use you can use it way beyond if you don’t mind re cleaning and lessor results.

Like you, I preclean the larger parts of a watch before running them through my cleaner, and you are right, that helps extend my cleaning solutions life. I do not clean anywhere's near the amount of watches you do, so I guess I shouldn't complain about buying expensive cleaning solutions when needed.
My wife does buy the cheap coffee filters, maybe the Melitta filters will work better.
I just read an article about how to make good coffee and the article said not to use the cheap filters for making coffee. Maybe the same applies to cleaning solutions!

The pre cleaning I will mob up all the pools of oil you often find, then using a alcohol and peg wood remove all dirt and grease as possible, if the spring is good draw it through watch tissues soaked in alcohol several times you find a lot of grease and dirt etc, sometimes I will immerse plates in a bath of alcohol and brush the worst off the good thing is while you are doing all this you are inspecting the parts in detail and will often find other problems in doing so.

How do you use alcohol with the peg wood, wet the tip of the pegwood?

I keep a new razor blade and sharpen to a fine point the peg wood, and when dirty remove dirty points, then quickly dip in the alcohol it normally will bring enough across to work with I often will do this several time until you can see the clean jewel face.

Not too repeat What has already been said, but i think Chris is right The cost of the cleaner is not that much so always use name brand cleaner either L&R or zenith and when it starts too get dirty cahnge too clean product.

I get several watches each month that are so oily they leave the top of the bench wet with oil,,when i change cleaning soultion it is still good enough that a lot of folks would still be using it,,so i save some of the used cleaner and rinse for these very oily watches and do a pre-clean in a old tank style ultrasonic before i put tham in my Tempo cleaning machine.

Earlier in this post I stated that I use water, vinegar, and Dawn dishwasher soap in My ultrasonic cleaner. I just got back to a unit I did several weeks ago to try to finish it and found a white dry scum on all the gears. Apparently the water evaporated as well as the vinegar but the Dawn left it's residue (Soap Scum) on the parts. So I am now shopping for an affordable fluid to use in the Ultrasonic machines. I have a 2 liter unit so I would like to keep the price down. I am beginning to think the chemical ways of old are the best. Any suggestions? What about drying parts in sawdust to keep them from spotting? I have also been told "Just boil it for three minutes and let it cool naturally so it don't warp and thats good enough. I have an air compressor so blowing and drying are not a problem.
Patrick 1616