The art world colour-hogging feud between artists Anish Kapoor and Stuart Semple has added another notch to its belt. It all began when Kapoor secured the rights to exclusively use Vantablack – the world’s blackest black capable of absorbing 99.96 per cent of light – last year. Other artists felt left out, so Stuart Semple retaliated by creating the world’s pinkest pink, available to everyone but Kapoor. It sparked a campaign called #sharetheblack, where the artist called out Kapoor for monopolizing Vantablack.

Kapoor somehow got his hands on Semple’s pinkest pink, and posted a picture on Instagram of his middle finger luxuriously coated in a light dusting of the pinkest pink. The latest entry into this seemingly never-ending saga is Semple’s latest invention: colour-changing rainbow paints. The paints, called “Shift” and “Phaze”, are banned from being purchased by Kapoor. The reason why he’s barred from acquiring them, however, has changed.

Whereas before it was down to his hoarding of Vantablack, now Semple is taking up the cause for residents in Camberwell, who are neighbours of Anish Kapoor’s studio. Kapoor has plans to expand his studio another floor, which will block the light, according to a Change.org petition by local residents. “Recently Anish Kapoor has put in a plan to Southwark Council to build another floor on top of his studio that will block the light and view from the back of the properties. This is the peaceful side of the houses, where you can appreciate the sun when it shines and have a view of the sky over South London. A welcome respite from the busyness of the main road. If you live & work in a city it’s the small thing that is so precious.”

In order to air their frustrations in a public way, residents enlisted the help of Semple, who responded by releasing the two rainbow paints. Both use Chiral Nematic liquid crystal, which Semple’s studio explains is a living substance that is “more expensive than gold”. Phaze shifts from “purple haze to the pinkest pink” when exposed to temperatures of 24ºC to 28ºC; Shift changes from black to a spectrum of vibrant colours.

Watch clips of the rainbow colour-changing paints below. Your move, Kapoor.