I'm having the hobby to draw paintings with the tea I drink trough the day. Usually I pour a tablespoon of the hot tea away, wait until it dries and gets more concentrated, so the colour is more intense.
Most of the colours are dark greens or variants of brown. Mostly due to the oxidation.
To get blue and red I now drink tea of herbs and flowers with such colours, and have to pour the sip away early to preserve the brighter tones. Unfortunately after some time more than 80% of the dried tea becomes brownish.
I added some cold water to slow down the oxidation, but not much success, all I got was a small blue ring around a brown area. Next to my office is a small laboratory where I asked what to use, but no idea from that side.
As I'm not a chemist I just did a simple calculation: The opposite of oxidation is reduction, so I need some Reducing agent. Used Ascorbic acid with not huge success. Against rust and other effects of oxidation I can use industrial alcohol, so tomorrow I'll get a bottle of that. But as said, I'm just guessing here.
What can I actually use to hold or slow down the oxidation-process until the tea is dry?