The animators' drawings are traced or photocopied onto transparent acetate sheets called cels, which are filled in with paints in assigned colors or tones on the side opposite the line drawings.
ðɪ ˈænɪmˌeɪɾɚz dɹˈɔːɪŋz ɑːɹ tɹˈeɪst ɔːɹ fˈoʊɾəkˌɑːpid ˌɑːntʊ tɹænspˈæɹənt ˈæsɪtˌeɪt ʃˈiːts kˈɔːld sˈɛlz, wˌɪtʃ ɑːɹ fˈɪld ɪn wɪð pˈeɪnts ɪn ɐsˈaɪnd kˈʌlɚz ɔːɹ tˈoʊnz ɔnðə sˈaɪd ˈɑːpəzˌɪt ðə lˈaɪn dɹˈɔːɪŋz.