Now You See It, Now You Don't

I bought this cheater panel (I hear they're called "convenience panels" nowadays) at a yard sale more than a year ago to practice machine quilting on my HQ16. I loaded the machine like I normally would with a "real" quilt and doodled with regular thread on top and water-soluble thread in the bobbin. Recently, I decided to see if my plan for the water-soluble thread would work...

I spritzed the back of the quilt with a spray bottle filled with water and voila, the bobbin thread disappeared and I could easily pull the top thread off. Now I can start all over and quilt this panel again.

There are several companies that make water-soluble thread, including Superior Threads. They recommend using it for trapunto, basting, etc, but warn against using it on swimwear...