Hi guys, I'm chiming in a few days late, but Hopefully can contribute... I've doped hundreds of cones... yes hundreds.
Refc's concerns are correct, but not necessarily an issue for a light coat... (more of a problem on ported boxes than sealed)Sealed box woofers handle doping better, so for much mass, your driver needs to have enough Xmas and sensitivity to blend.
Doping adds mass, which lower FS, raises your final QTS and will in some way cut sensitivity.
I have always used doping as a tool trying to achieve a final outcome...
Also, different dampening materials have different effects.. Glue will stiffen a cone and could cause frequency extension (crossover should handle that).. Latex is a soft material and tends to smooth out peaks...
With that said, I would recommend a thin coat of latex on these old cones... The mass is insignificant to change spec of the driver to an audible change, but I have always found the smoothing of the peaks in these old cones audible.
If you have an old gallon of paint sitting around, open it carefully without shaking, you will find that the latex has separated from the pigment. Use a single coat and take a listen. This is very minor and will not effect your drivers overall spec. If needed, you can even add a second thin coat, but, I would stop there.
