He has no colour of his own. What you are looking at is how thick he is.
film--nm
alive--s
reads--
Touch him and he goes.
One film, the whole palette
Solana does not have a palette, it has a set of hex codes that happen to be what a soap film looks like at five particular thicknesses. Measured here in dE*ab, against the CIE 1931 observer under D65.
03006009001200 nm
| Solana | hex | film at | reads | dE*ab |
|---|---|---|---|---|
| measuring | ||||
A soap film reflects at most 7.7 percent of the light that hits it, so this page runs the brightness up about 13 times. Turned down to the truth he would be almost invisible here.
The reading
Nothing on him is pigment
Light bounces off the front of the film and off the back of it, the two copies arrive out of step, and whichever wavelength cancels is the colour missing from what reaches you. Change the thickness and you change the colour. Nothing has been dyed.
He drains, so he moves down the strip
Gravity pulls the liquid to the bottom of the wall and the top thins by the second, so the colour never sits still and the order never changes. He opens on Solana purple, a film 417 nm thick, and works down from there: amber at 350, ocean blue at 266, violet at 210. Then he runs out of colours. White at 103 nm is as bright as a soap film is ever able to be, and under 30 nm there is nothing left to see. Blow a small one and he starts at 702 instead, which is Solana green, because the same liquid on a smaller wall lies thicker.
The last colour is the page
Under about 30 nm the two reflections cancel across the whole visible band and the film turns black. Hooke showed that black patch to the Royal Society on 28 March 1672. Newton put a number on the coloured film, around 107 nm, and both of them noticed the same thing: the black arrives, the thinning stops, and the film has minutes at best. He does not fade to white here. He fades to the background.
You have never seen a bubble pop
The hole opens and the rim runs away from it at the Taylor and Culick speed, the square root of twice the surface tension over density times thickness. For soapy water that is tens of metres per second, so the whole thing is over in a few thousandths of a second. Every burst bubble you can picture came off a high speed camera. This one is slowed down and the real duration is printed under it.
The record holder is not a bubble
Physicists in Lille kept one intact for 465 days and published it in Physical Review Fluids in 2021. They did it by loading the wall with plastic particles and glycerol, so the water could neither drain out of it nor evaporate off it. To make a bubble last, they had to stop it being a bubble.