The use of bitumen as a glaze to set in shadow or mixed with other colors to render a darker tone resulted in the eventual deterioration of many paintings, for instance those of Delacroix.
ðə jˈuːs ʌv bɪtˈuːmɛn æz ɐ ɡlˈeɪz tə sˈɛt ɪn ʃˈædoʊ ɔːɹ mˈɪkst wɪð ˈʌðɚ kˈʌlɚz tə ɹˈɛndɚɹ ɐ dˈɑːɹkɚ tˈoʊn ɹɪzˈʌltᵻd ɪnðɪ ᵻvˈɛntʃuːəl dɪtˌiəɹɪɹˈeɪʃən ʌv mˈɛni pˈeɪntɪŋz, fɔːɹ ˈɪnstəns ðoʊz ʌv dᵻlˈækrwɑː.