Hi, David. HAL-O JR and other Herbie's Audio Lab damping products are not frequency-specific. They diminish the whole spectrum of frequency vibrations. Specific frequency/dB ratios will vary somewhat from one vibrational environment to another and among different tonearms. You'll get varying degrees of diminished vibration, not so much a "shifting" of resonance frequency or linearity, resulting in a more faithful musical rendering. Typically, the greater a specific frequency's amplitude, the more it will be diminished.
HAL-O JR will reduce a tonearm's resonance frequency substantially, as well as the full gamut of micro-vibrations affecting the tonearm. A tonearm, like all solid materials in an audio system, does not vibrate only at a specific, dominant resonance frequency, but also suffers micro-vibrations throughout the audible spectrum and well beyond. Oftentimes, it's micro-vibrations of much higher frequency and much lower amplitude that cause some of the glare and grunge, and other anomalies, in music. For essential micro-vibration control, you need to address vibration with a whole-spectrum approach.
Among the materials mentioned in your post, each of the ideas is viable (cotton has perhaps the least potential, though). Plumber's Teflon tape, the kind you wrap around pipe threads, can be very effective at tonearm damping, wrapped several layers thick at a specific location or locations on the tonearm, or around its length. Experimentation/audition is about the only way to determine the most appropriate approach for a given application. What's appropriate for one tonearm/system will not necessarily apply to the next. Trying to pre-predict or pre-engineer a solution can be futile compared to actual trial-and-error auditioning by ear.
Acute micro-vibrations that cause loss of ambient vitality and "live" accuracy are often of such low amplitude that they are imbedded within the noise floor of electronic measuring equipment, so charting them can be illusive, measuring them impossible. Reduction or elimination of these vibrations is readily audible, however, to the discerning listener.
Herbie's Audio Lab