What to wash the wool with when felting?

[dex_millie]

I was going to felt the wool, but I read somewhere I shouldn't use regular detergent, so then what do I use to wash it? Also when it is a finish product do I still not use regular detergent (like dreft) is there something special I need to get to wash it with?

[mamapixie]

I used regular detergent when I felted my sweaters, in part to strip them of all the other stuff on them from the previous owners.

When it is a finished product, I use wool wash(like from Northern Essence), that way the wool is continually getting lanolized.