Hello.
A few hints and tips for all those using or thinking of using u/s cleaners, having spent more years than I care to remember in the silver and gold trade, u/s cleaners are a tool used every day. I have 2 u/s machines of commercial spec, 1 that is used daily that will accomodate a 4 mm loco, and 1 that is rarely used but could probably fit 5 or 6 7mm locos at once. (don't ask how much that one cost)!
Both are used heated, don't ask me what temperature but if you can just about bear to put your hand in it thats about right.
There are many u/s cleaning solutions on the market, but I have always used Fairy liquid (original) and ammonia, smells, but very effective, will work cold but the warmer the solution is the more effective it becomes. After cleaning a good rinse in clean tap water hot or cold will leave the surface clean enough for electroplating, so will also be clean enough to accept paint.
The plastic basket or tray assists you in removing parts but its main function is to protect the tank, metal parts coming into contact with the tank sides and bottom will cause damage to the machine.
U/S waves will travel through any material, when using for small parts a plastic sieve that floats on the surface works fine and will collect anything that decides to fall off.
Cellulose thinners and any other solvent can be used in a jam jar or similar placed into the u/s solution but not making contact with the tank itself, please be aware of the flashpoint of anything you use.
Always have an old toothbrush to hand to assist with stubborn deposits.
Prolonged exposure of u/s waves to your hands may cause damage to tissue but having used it as the best hand cleaner in the world for many years, nothing has fallen off......yet!
Hope this has been of some assistance.
Chris