Lately I'm noticing clothing labels that say "Do Not Use Fabric Softener in the Rinse". The last thing I want is another category of Laundry that demands special treatment since I usually use FS. What's the science behind these fabrics?
You're not supposed to use fabric softener on flame retardant clothing, but I thought that was mainly used in children's clothing. Are you possibly a very small fireman, LOL?
Perhaps more useful: Softeners are also not to be used on fabrics which are designed to be moisture-wicking, such as clothing from the currently-very-popular Under Armour brand. This ban includes dryer sheets. Both powdered detergents and softener are strictly verboten for Gore-Tex items.
I don't know about what products are around in the US but here there are two basic types of liquid softener - over-perfumed waxy gunk that leaves a film over the clothes (and the inside of the washing machine), and thin liquids whose main purpose seems to be just to neutralize any detergent that didn't rinse away. Guess which type I now use?
I used to be a strict "no softener" person till my skin became really sensitive and I had real problems with detergent residue. I now use a gentle detergent (Abode or Earthwise) and Enviroclean Fabric conditioner. No more skin rashes. I believe the conditioner helps neutralize any traces of detergent. It leaves no detectable residue on clothes of the machine, and no smell.