Thread: 6.5L Ultrasonic cleaner REVIEW

Here's another chemical that can get improved results in an US cleaner.

I have been taking apart a non-operating 90cc Chainsaw powered concrete cutting saw and most of the 6mm hex screws holding it together were greasy, rusty and/or crudded up with cement. Some of the hex screw sockets were full of cement and to get these out I ground a fine chisel end onto an old chainsaw file and that enabled me to chip out enough of the cement to insert a hex key, but now I faced with how to clean them up.

Here is a close up of what some of the screws looked like.
This is the batch that got US with CLR.



All of the standard concrete/cement cleaners involve some form of acid but as some of the screws still had a zinc coatings and I wanted to lose as little of this as possible. Then I remembered CLR gets calcium, lime and rust stains off various things and when I looked this up I see it contains 30% Lactic (a weak) acid and a wetting agent, so I thought his cleaner might not remove too much of the Zn provided I did not expose the screws for too long.

The instructions on the CLR container call for use from "neat", to an 8:1 dilution with water, for 2 minutes before washing it off

This is what a selection of the bolts looked like before the test.

I divided the screws into 4 groups of ~7 stews and the plan was to subject these to various cleaning by
water (soak only), water in the US unit, CLR (soak only) and CLR in the US

I ran the test for 3 x 2 minute intervals (total of 6 minutes) until at least one of the batches were clean


Of course I didn't expect a water soak would do much which it didn't.
Using Water in the US did nearly as good a job as the CLR soak.
The long screw in the CLR&US batch was very greasy and rusty and could be improved on.
It's likely I could have got the good results with a much longer CLR soak but I did not want to lose any more zinc.
A longer water & US might have removed more of the cement but is unlikely to remove much more of the rust

I have no idea how much zinc was removed by the CLR but it looks like most of it is still there - I will now leave them for a few days and see how much they rust.

A similar chemical that might be worth a try for such a circumstance is very dilute vinegar.

Originally Posted by BobL

Here's another chemical that can get improved results in an US cleaner.

I have been taking apart a non-operating 90cc Chainsaw powered concrete cutting saw and most of the 6mm hex screws holding it together were greasy, rusty and/or crudded up with cement. Some of the hex screw sockets were full of cement and to get these out I ground a fine chisel end onto an old chainsaw file and that enabled me to chip out enough of the cement to insert a hex key, but now I faced with how to clean them up.

Here is a close up of what some of the screws looked like.
This is the batch that got US with CLR.



All of the standard concrete/cement cleaners involve some form of acid but as some of the screws still had a zinc coatings and I wanted to lose as little of this as possible. Then I remembered CLR gets calcium, lime and rust stains off various things and when I looked this up I see it contains 30% Lactic (a weak) acid and a wetting agent, so I thought his cleaner might not remove too much of the Zn provided I did not expose the screws for too long.

The instructions on the CLR container call for use from "neat", to an 8:1 dilution with water, for 2 minutes before washing it off

This is what a selection of the bolts looked like before the test.

I divided the screws into 4 groups of ~7 stews and the plan was to subject these to various cleaning by
water (soak only), water in the US unit, CLR (soak only) and CLR in the US

I ran the test for 3 x 2 minute intervals (total of 6 minutes) until at least one of the batches were clean


Of course I didn't expect a water soak would do much which it didn't.
Using Water in the US did nearly as good a job as the CLR soak.
The long screw in the CLR&US batch was very greasy and rusty and could be improved on.
It's likely I could have got the good results with a much longer CLR soak but I did not want to lose any more zinc.
A longer water & US might have removed more of the cement but is unlikely to remove much more of the rust

I have no idea how much zinc was removed by the CLR but it looks like most of it is still there - I will now leave them for a few days and see how much they rust.

A similar chemical that might be worth a try for such a circumstance is very dilute vinegar.

Thanks for the info and pictures Bob. This thread has generated more info than I expected. Cheers, Simon