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Ultrasonic Cleaner

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Brian O'Connor09/07/2020 07:56:58
68 forum posts
16 photos

I have recently bought an ultrasonic cleaner to accomplish the following tasks:

Clean loco components such as injectors and clacks

Remove slight surface rust from small nuts and bolts

Clean airbrush after using oil-based enamel

Can someone please suggest what I should add to the water, and how much, to achieve each of the above. Thanks.


not done it yet09/07/2020 08:40:03
4739 forum posts
16 photos

I would likely put nothing in the water except a beaker holding the parts, along with any suitable solution for cleaning the items in hand.

roy entwistle09/07/2020 08:48:12
1189 forum posts

I usually put a squirt of washing up liquid in the water in the tank and vinegar in the beaker. depends what you are cleaning I suppose


JohnF09/07/2020 09:29:28
999 forum posts
142 photos

Brian, use the keyword search at the top, just put ultrasonic in and there are heaps of posts, the second one down is pertinent to your question.

I’m sure you are already aware there are many specialist cleaning additives available from one of “ours advertisers Machine DRO (no connection other than a happy customer)


Andrew Tinsley09/07/2020 10:32:40
1148 forum posts

Using an ultrasonic cleaner with just water isn't too smart. You will need a surfactant of some sort even if it is just washing up liquid.

There isn't just one correct surfactant, it depends on what you want to clean. There is plenty of information on the web to make the right choice.


Nigel Graham 209/07/2020 11:37:00
667 forum posts
15 photos

I would be surprised if an ultrasonic cleaner will remove slight surface rust, or lime-scale which I assume is what is in the injectors. They are really for removing grease and similar contaminants, and particles adhering to the grease. They might clear water-treatment residues (tannin) from boiler-fittings though.

I would advise cleaning the air-brush in the appropriate solvent first, not relying on just the ultrasonic bath. Use that for a last rinse.

The cleaner manufacturers will advise on what additives, but naturally will almost certainly recommend the ones they sell! However, as I recall from work, the normal additive is basically a detergent with a pH-adjuster making it slightly alkaline, so as Andrew suggests, ordinary washing-up liquid will probably work as well as any.

You may also see advertised, second-operation rinse-aids for these cleaning-tanks, but I doubt we'd need these for our processes. They are for very fine surface-preparation such as prior to using specialist adhesives.

I would not use vinegar for grease-removal. A mild alkali such as detergent or washing-soda is better for that. (Hence all that present advice about washing our hands with soap and water!) It is also a bit kinder to ferrous metals than an acid.

Acids will go for lime-scale, but be careful not to pickle the injector cones and valve-seating themselves.

Some of these cleaners also heat the water, making the action more efficient.

I would not put the items in a solid-walled beaker either, unless by advice or suggestion in the machine's own operating-manual. A thin-walled container made of plastic of similar density to the fluid might be OK, but otherwise any container not matched acoustically to the bath will simply reflect lot of the sound back off its outer surface, and heavily attenuate any that does manage to penetrate the wall. A beaker will only help handling the work-pieces, but hinder cleaning them.*

Use the work-basket supplied with the cleaner, suspend the work on thin wire or string, or just lay it on the tank floor - and never put your hands in the water when the tank is running.


*(This matching necessity explains the gel used in a medical ultrasound scan. It prevents an air-gap between transducers and skin, and helps the sound to pass with minimum attenuation across the boundary caused by contact between materials of different densities and sound-transmission speeds. The scan itself is detecting the echoes from similar acoustic boundaries within the body.)

pgk pgk09/07/2020 13:21:35
1846 forum posts
288 photos

The ultrasonic cleaner we used for surgical instruments had two trandsucers under the base and one could easily see the fluid waves produced from each one locating their position. I suspect that placing a flat bottomed glass beaker on the spot might not reduce efficiency much at all (subject to experimentation as to whether the visible waves are seen in beaker fluid)

Cleaner frequencies are around 40kHz and google tells me that lower frequencies 20-25kHz are used for large metal masses whereultranic erosion matters not.

Medical ultrasound 3MHz - 25MHz if mempry serves. We generally used 10MHz for cat-sized pets and 7.5-5MHz for medium to larger dogs. 25Mhz was specialist stuff I never got to play with..things like corneal tissue


Howard Lewis09/07/2020 17:07:37
3375 forum posts
2 photos

Based on my experience of cleanliness checking cast iron components, my advice would be "Don't over do it"

As soon as the part is as clean as you want it, switch off and take it out.

It did not matter how many times we cleaned the part, ferrous material still detached, to be picked up by the magnet.


JasonB09/07/2020 17:35:36
18305 forum posts
2024 photos
1 articles

If you have not been able to find them via Machine DRO then Allendale Ultrasonics do several fluids

Brian O'Connor10/07/2020 08:57:54
68 forum posts
16 photos

Thank you, gentlemen, for all your replies. I am now well set up for tackling the first two items on my list, but still have to find advice on how to clean oil-based paint from an airbrush. All the advice I can find on the web is for removing acrylic paint, so not much use. I shall just have to experiment by painting a bit of scrap metal and starting off with household detergent.


pgk pgk10/07/2020 10:04:06
1846 forum posts
288 photos

No experience with airbrushes but trying to clean ordinary oil based paint brushes with detergent has never gone well for me... white spirit or acetone until it looks clean then a final go over with shampoo before rinse, shaking dry(ish) and wrapping in kitchen paper to keep the brush shape and bristles soft is the method I follow.

Beaker of acetone sat in the water??


Barrie Lever10/07/2020 11:09:08
651 forum posts
75 photos


Absolutely the best way to clean parts of the airbrush is to jet squirt it with acetone whilst the oil based paint is still wet, then to final rinse the parts with what ever thinners you used with the paint, this final rinse can be the airbrush re-assembled and just spraying thinners.

I use the type of bottle shown below, you can buy these on Ebay.

If the paint is dry and gummed up then soaking in acetone is the way to go.

Getting the bulk (99.5%) of the paint off with acetone is by far the best way, acetone is quite environmentally friendly and not particularly dangerous despite it's properties. It is not a VOC.



Nigel Graham 210/07/2020 13:19:50
667 forum posts
15 photos

Oil-based paints are dissolved by white spirit.

Synthetic enamels need their own thinners such as xylene (or acetone?)

Cellulose paints are soluble in acetone - so are uncured synthetic resin and its two components (e.g. 'Araldite', car body-fillers).

I am not sure what attacks acrylic paints, but some paints are water-soluble, helped by washing-up liquid.

NB_ these while the paint or adhesive is still wet!

Once hardened, they can be dissolved only by appropriate strippers, and they might damage the painted or glued material. Solvents for cured resins do exist, but are nasty materials and might not be easily available to private purchasers.

Grindstone Cowboy10/07/2020 21:05:14
311 forum posts
27 photos

I use Seaclean2 which seems pretty good on most things, and will remove light rust - it does sometimes leave a kind of grey deposit that can be easily brushed off, it must depend on the alloy as it does not happen every time.. Don't think it will work on paints though.

I use the "solution in a container in water in the cleaner" method and have had no issues so far - an old Pot Noodle container works fine, but does tend to float a bit.

(Note - I found that link does not work with the latest version of Firefox unless you enable older security protocols)

Hope this helps.


Neil Wyatt11/07/2020 10:00:10
17970 forum posts
709 photos
77 articles

I'm a convert to the non-spirit brush cleaner for oil based paints. I found it works better and quicker!

I tried it after using an airbrush cleaning liquid with similar contents that works for enamels and acrylic.


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