My beautiful obsession

Okay, okay, I realize I have been a little relentless about my pursuit of the "elusive periwinkle".

Here are my latest results. I promise to drop the whole thing now. But I am by no means satisfied, and I'm wondering if those of you with more experience with dyeing might have some insight into this.

The cloth with the splotches was my experiment, mixing up various proportions of boysenberry and turquoise and applying it to white cotton with a paintbrush. The ratio I settled on, the column of splotches in the centre of the photo, was 1 part boysenberry to 3 parts turquoise. You can see how the turquoise migrated away from the boysenberry.

The nicely pressed and folded results are nowhere near as blue as they should have been. In fact they pretty much look like pure boysenberry. Is this because I didn't use extra hot water (125 degrees), which is recommended for turquoise? It looked quite blue until I added the soda ash. I am chagrined.