Some tow, I have discovered, is treated with a fire retardant. However, many of the vendors don't know if their tow has been treated or not.
I bought some tow from Smiling Fox a number of years ago, specifically to try as tinder with a new flint and steel. I couldn't get a fire going with it to save my life, but starting a fire with the same flint and steel, and char from the same batch, was no problem with some of the other tinders I used. I finally tried just lighting that tow with a match, to see what would happen. I found it would smolder and disintegrate, but would not flame. I researched it some, and discovered the issue of fire retardant.
You could ask the vendor if his/her tow has been treated, but chances are they won't know. I think your best advice, if you want to use tow, would be to follow the excellent recommendations provided by Brokennock and Carbon 6, even if your tow has been treated with a fire retardant. That little bit of extra lube will probably help keep your fouling soft. I might also suggest you look up the thread on wads started recently by Smokey Plainsman. I had no idea that bore-sized cut wads had been in use for so long... Since the mid 18th century! Spence 10 provided documentation of this. Also, the "Bevel Brothers" wrote an article about testing various wad materials in the June 2020 issue of Muzzle Blasts. I don't know how round balls would be affected, but with shot loads, they found there was a jaw-dropping loss of velocity and pattern density when shooting wadding of grass fiber as compared to card wads. I would expect similar results with tow, authenticity notwithstanding.
It's always good to experiment, provided you keep safety foremost.
Best regards,
Notchy Bob