I need to quit switching colors to be sure. That green one was a whole lot brighter than the others. I think the warm water probably had the biggest effect. It will be room temp after work and I'll do another green to see.
The green ones do seem the brightest. I'm going to do a test too, as we are saving jugs and planning on a luminary pathway out to the haunt. I wonder if you put aluminum foil on the back side or bottom of the jug, what that would do? Just brainstorming.
This is glycerin at room temp. not as bright as the warm water green but brighter than the original blue. I think the glycerin helps but warm water seems to be the biggest factor. Being in NE Ohio, I don't think I can keep them warm so I will go with the glycerin and maybe a couple of drops of dish soap for what it's worth. I would be interested if foil helps.
Left hand is the original. Right hand is blue with the glycerin added. not much difference.
This is glycerin added plus about 3/4 L of tonic water. This was a suggestion from my 7 year old grandson and it didn't help much. I think the color is the biggest factor and we may be going with tap water. We will still be way cooler than the neighbors.