Stuart Semple hates Anish Kapoor. He hates him so much that he requires those who purchase his paints to sign that they are not Anish Kapoor, are not buying them for Anish Kapoor, and will do everything they can to make sure they do not end up in the possession of Anish Kapoor.
Semple is metal as fuck. He made the Pinkest Pink after Kapoor bought exclusive artistic rights to Vantablack, then after Kapoor taunted Semple with a picture of his middle finger dipped in Pink, Semple made Diamond Dust, which is glitter made out of literal glass shards. He also made Black 2.0 and later on Black 3.0 because fuck Anish Kapoor.
It's not just Anish Kapoor he's against; he's against the whole monopolization of art materials and colours. He made TIFF Blue (versus Tiffany Blue), Easy Klein (versus International Klein Blue), and even Freetone (versus Adobe and Pantone).