Here is are some interesting articles on 'when soda ash is NOT soda ash', which talk about what looks like soda ash, is not always soda ash:
Kevin Dunn re: soda ash or not soda ash: http://cavemanchemistry.com/HsmgJojoba2011.pdf
I know this is coming a year later, but I found this info from Kevin Dunn very interesting, but I'm wondering if there is accompanying info about what is causing all those things that aren't soda ash? Maybe you just had to be at the presentation. I'd love any additional info about the other causes and possible cures.