@erik_squires - when used as an insulation Cotton performs better (i.e. improved clarity) due to its lower value of dielectric constant (Dk).
- Vacuum is 1.0
- Air is 1.1
- Cotton/silk is 1.3
- Foamed Teflon (e.g. Airlok) is 1.4
- Teflon is 2.2
- PVC and rubber variant are much higher
The insulation charges and discharges with the change in polarity, which impedes the transfer of the signal.
The lower the value of DK results in a more accurate signal transfer
For more details on cable design take look at...
https://www.psaudio.com/copper/article/cables-time-is-of-the-essence-part-1/
https://www.psaudio.com/article/cables-time-is-of-the-essence-part-2/
https://www.psaudio.com/article/cables-time-is-of-the-essence-part-3/
I have tried all of the insulation mentioned above and the very best to date is inserting bare wire into a teflon tube with a larger diameter bore. The teflon tube does not collapse like cotton or silk, which results in a layer of air between the wire and the teflon tube - this is about as close as you will get to an air insulation.
Using this technique to insulate wires in cables produces exceptional details and clarity.
I use it in all my DIY cables.
Hope that helps - Steve