Working Tip: Work neutral to oxidizing for best results. A reducing flame will cause red streaking.
 
Artist Description by Mike Shelbo:
"Tonic is a transparent blue, the color of an aquamarine gem. The color becomes more vibrant and its higher refractive index shows when used with itself in applications that allow the Tonic layer to be as thick as possible.
When used as tubing, applied on clear or as coiled color, if the Tonic will be exposed to a lot of different working flames and long times in and out of the kiln, I advise a thin clear coat to protect the surface from overworking. Too much propane in your flame can result in a copper reduction leaving you with red streaks or patches on the surface of the un-encased Tonic. Too much over oxidizing can leave you with a surface haze or scuzz that must be swiped to remove.
I often recommend a thin layer of clear frit over Tonic or evenly coated clear rod over your entire prep. I have used Tonic without encasement many times on solid sculpture and had good results, but I have seen a warming or flashing flame haze up a section.  Working Tonic in as close to a neutral flame and away from the face of your torch is wise and will get you the best results with the color.
If you have worked Raindrop in the past, this color is very similar in working properties. My favorite application is to gather up rods into 18mm or thicker sections and sculpt them into figurines. This next generation transparent is definitely a must have to fill out the rainbow palette. It can be layered over other colors like white for a nice pastel, but will be a faint tint unless applied as a 5-7mm thick layer. The first impression Tonic made on me was the thought that it was the color of window glass or old soda bottles, both aqua blue colors that I have always been fond of.” – Mike Shelbo