#126Oil Slick Iridescence

A film of oil creeping over dark wet water. The thickness is a base level plus a domain-warped fBm, so the surface pools and swirls the way a real slick does, dragging the sheen with it. Each thickness drives genuine thin-film interference — three wavelengths sampled with a cosine reflectance sweep the whole Newton series — and the resulting hue is rebuilt on the Oklab ring, so silvery orders desaturate on their own and the wettest-thin patches let the near-black substrate show through. Press to swell the film under the pointer.