1. Water is for all intense purposes classified as nonionic; ASTM D1193, Standard Specification for Reagent Water, Type 4 achieved by distilled water (condensation of steam) has a resistivity >200K ohms and a total dissolved solids <2.5 ppm.
2. In general, surfactants can be:
-nonionic (if you measure with TDS - there will no change),
-anionic ionize in aqueous solutions so that the hydrophilic head has a negative (-) charge. Anionic surfactants are the backbone of all general detergents.
-cationic ionize in aqueous solutions so that the hydrophilic head has a positive (+) charge. Cationic surfactants are not very good detergents but they can kill viruses so are very common in disinfectants and if a residue is left behind can acts as anti-static because they absorb water from the air making the record electrically dissipative to static, but this capacity decreases below 35% humidity.
-amphoteric can ionize in aqueous solutions so that the hydrophilic head, depending mostly on the solution pH, is either anionic (-) or cationic (+).
3. Ionizing the fluid in a general wash - such as laundry soap - helps to remove particulate from clothing by charge repulsion. However, particulate adhesion is governed by a number of factors. The paper Adhesion and Removal of Fine Particles on Surfaces, Aerosol Science and Technology, M. B. Ranade, 1987 shows for aluminum oxide particles, the force (acceleration) required to remove a 10-micron particle is 4.5 x 10^4 g’s, a 1-micron particle is 4.5 x 10^6 g’s and a 0.1-micron particle is 4.5 x 10^8 g’s. A simple brush or wipe is not going to get the smallest particles/debris that can ‘hide’ in the valleys between the groove side wall ridges. As fluid flows past a hard surface, such as a record, a boundary layer is developed and depending on its thickness (upwards of 5 microns) it will essentially shield any particles within it. So, agitation is critical in reducing the boundary layer to expose the surface with its particles to the cleaning fluid and the fluid velocity (shear force) that can remove them.
4. The lower the ultrasonic frequency, the larger the cavitation bubble that is created. A 35-40 kHz UCM will produce bubbles about 75 microns diameter. These are not going to get into the record groove. A 120 kHz UCM will produce bubbles about 20 microns and these can get into the groove. But the larger bubble 'can' produce more energy when it collapses/implodes (cavitation) so there is fluid agitation around the collapsing event that can provide cleaning. How violently the bubble collapse is determined by the amount of power provided by the ultrasonic transducers but only up to point above which more power has no benefit.
5. Further complicating the effectiveness of ultrasonics is the fluid boundary layer. The fluid flow at the record (or any) surface develops a static layer that is separate from the bulk fluid that is moving. The boundary layer thickness is dependent on the ultrasonic frequency (high kHz = thinner boundary layer), acoustic energy, and fluid properties (viscosity & density). To get the most effective cleaning, the cleaning process has to penetrate the boundary layer to remove the soil and particles that are contained within it. At 35-40-kHz, the boundary layer can be as thick as 5 microns, while at 120-kHz, the boundary layer can be as thick as 2 microns.
6. There are other variables, but depending on the initial cleanliness level of record, an ultrasonic tank with just a small amount of a high performance nonionic surfactant (such as Tergitol 15-S-9) can effectively remove light soils (finger prints, etc) and particles. However, for heavily soiled records (i.e. flea market), a pre-clean step using more aggressive cleaning agents (such as Alconox Liquinox which is a combination of nonionic & anionic surfactants) or a wide range enzyme (soak) cleaner is generally necessary.
7. As far as mold-release, the following is sourced from the RCA patent
US3960790A - Disc record and method of compounding disc record composition - Google Patents
for vinyl records which is probably the best knowledge we have for vinyl record composition: Lubricant: 0.4% of an esterified montan wax. The wax also acts as a mold release. When the record is removed from the press without the lubricating effect of the montan wax ester in the compound, the grooves of the record are sometimes fractured, torn, and deformed by the removal. These faults in the groove produce noise on playback. Montan wax ester at the stated percentage is compatible with the resins and is "homogenized" into the surface of the record at the normal pressing temperature. If more than the stated amount of the montan wax ester is used, the excess amount is not absorbed into the surface of the record. Its presence results in non-uniformity in the surface of the record, particularly as related to the friction between the stylus and the groove. This non-uniformity produces noise when the record is played. Overall, a good record should not have any mold release to remove. Otherwise, the discussions on removing mold release may actually be associated with excess lubricant which should not be common.
8. Big problem with old records is the buildup of residue from any number of sources be it detergent residue, hard water scale, tar from smoke, and who knows what. In these cases, as previously addressed, a range of different chemistries with different methods for pre-cleaning is generally required, let just say they may need a lot of love.