From J. Charles Holt
Your article on diffraction gratings as a method for colouring materials is interesting (28 February, p 24), but I have to question its practicality. Mool Gupta reportedly suggests that the ability to embed colour into a material would eliminate the need for “expensive” painting.
What the article fails to mention is that any material which gets scratched would lose its colour just as a painted object would. What’s more, you would not be able to correct the problem by slapping on a coat of paint. Instead, you would have to replace the entire surface – a far costlier proposition.
Louisville, Colorado, US
