Stains in Carpet

One of the main ingredients in Childrens Advil Blue Raspberry just above water and below Ibuprofen is Blue Dye #1.  Carpet is dyed at the mill either after or before becoming a solution.  Last week my son spilled this in a big blob over my showroom carpet.  My first concern was my son to see if he had ingested any of the Advil to see if we had to go to the emergency room or not to have his stomach pumped.  After realizing that most of the Advil was either on his shirt or on my floor I decided to give him water and crackers to absorb anything he had ingested and proceeded to clean my carpet.  Of course this isnt a how to raise a child site and it isnt easy cleaning up a mess with a 20 month old trying to help you.  But the stain came right out with water and white towels.  There was still a blue haze on the carpet the next day but I put a wet white towel down on it and repeated and the haze was gone.  Why did this work? The carpet was a solution dyed polyester some of the best carpet when fighting stains.