In this article, we look at the evolution of the comb industry in Portugal from 1880 to 1970 with the aim of understanding the technological, economic and social impact of celluloid in the national context. Based on historical and statistical sources and the chemical analysis of historically significant Portuguese combs from the collections of the Martins Sarmento Society and the Guimarães House of Memory, we explain that the introduction of celluloid by the Guimarães comb industry in 1895 revolutionised the industrial context of Guimarães, transforming it into a centre for the production of (semi)synthetic plastics from 1950 onwards. Celluloid had an impact on the market for imitation tortoiseshell, sought after by the social classes with low purchasing power, and coexisted industrially and commercially with horn, the traditional material used to make combs.