Russell, The aluminum foil blows out because it is so thin. Normal parts are fine. Basically, the sonicator speeds up how quickly cleaning solutions take effect. If you wouldn't let a part sit in a solvent for an hour, then don't use that solvent in a sonicator. For instance, I won't put painted or plastic parts in acetone.
Here are photos of cleaning an old baitcasting reel. I used the sonicator to solvent clean many of the parts.
The reel pre-cleaning and then disassembled. While a sonicator can remove dirt from assemblies, the cleaning works best the more the reel is taken down. Everything was first scrubbed with Dawn liquid and a toothbrush followed by a hot water rinse. The handle and pillars were sonicated in vinegar/water, then rinsed.
The handle knobs were still sticky after the vinegar/water. The knobs are riveted onto the handle, so cleaning as an assembly was the only option. The handle was placed in a small jar with 1/2 oz of mineral spirits. The jar was suspended in the ultrasound bath. The first photo was after about 5 seconds. The second photo after about 3 minutes. Flip the handle and repeat. The mineral spirits cleaned the goo from under the knobs.
Much better... While the mineral spirits look nasty, they can still clean. All the screws and end caps were sonicated in the mineral spirits to remove old oils and grease. The first image shows a screw before and after cleaning. Note, the clean screw shows missing plating. If the plating is loose, it will fall off. The second photo shows some parts in a larger jar of acetone. The acetone removes any dirt that the mineral spirits or Dawn liquid leave behind. The third and fourth photos show the parts after cleaning and the detritus. As usual, lots of dirty Q-tips and used pipe cleaners. While the solvents in the jars look nasty, they are still fine to use. When they get too dirty to see through, I will run them through a coffee filter to remove the particles.
The reassembled and lubricated reel. The spool had a balsa wood arbor to reduce the line capacity. A previous owner had drilled additional holes in the spool, presumably to balance the spool (visible in the photo of the cleaned parts).
Additional recommendations:
- Don't place anything on the bottom of the sonicator. Sonicators are designed to have the water bath cool the ultrasound transducer. Items on the bottom will interfere with the cooling and blow out the transducer.
- I like to put parts in a plastic container, such as a yogurt cup or butter tub for cleaning with vinegar/water or Evaporust. I put parts in a glass jar (with a lid!) for cleaning with organic solvents. Suspend the container with a basket or by holding with tweezers.
- Don't fill the cleaner bath with flammable solvents (did you really need me to tell you this?).
- Fill the cleaner bath with warm/hot water. Warm solvents work better.
- Don't sonicate painted parts. Don't sonicate plastics in strong solvents, such as acetone or lacquer thinner.
Tom