I would give some hatian cotton shampoo a try if you happen to have that lying around. I'm assuming you have a cotton fringe. The reducers would defanlty help with the browning. Also if you have any oxidizer, you could try mixing up a solution of a rug shampoo of choice and a couple of ounces of a powdered oxidizer or Hydrogen peroxide. Spray liberally and extract with water. Dry quickly. Maybe shawn can confirm this but the reason I believe they use potassium carbonate in rx vs. sodium carbonate is the reactivity available. Potassium is more reactive and thus works a bit quicker in the oxidation process. Thus the oxygen for the oxidation is avaible quicker and thus less dwell time is needed to complete the reaction.