Have you seen this info on Rusk Anti Curl:
All About Rusk AntiCurl
I have had anti curl many times over the yrs. I loved how it made my hair easier to manage, loosened the curl, less bulky hair and less frizz even in humidity and I think it made it softer. I haven't had one since almost 6 yrs but am going to be looking into get another soon.
In that article it says they leave it on 20 mins for normal hair I guess that means unprocessed and 15 for processed.
3a/b medium/coarse but mostly moderately coarse, dense, strong strands
Komaza analysis current: medium to thick/ strands(mostly coarse), very strong elasticity, low porosity(some is), healthy strong hair
Goosefootprints: moderately coarse with some medium; low porosity at roots, normal thru shaft, porous ends.