Does the Deva foam have polyquats? Could it be buildup? I know several people have problems with polyquats, 4, 7 and 10 being the main offenders. I'm just throwing yet another thing out there.
fine - normal porosity*?- medium density - normal elasticity. Hard water. SoCal.
*Used to be low-porosity, but I lightened my hair 1-2 shades, so I may be normal-porosity now.

New climate! Current favorites:
Low-poo: CJ Gentle Cleansing Shampoo, Giovanni SaS
RO: V05 Kiwi Lime
Styler: UFD CM (old formula), FSG + CNPF
PT: CJ Repair Me, IAgirl's gelatine

Experimenting with: JC Confident Coils, JC Rockin Ringlets, CJ CIAB, gelatin gel

iherb discount code: CFN646