Observed [s/Fe] and [hs/ls] ratios for solar metallicity C stars from Abia et al. (2001, 2002) alongside the evolution of ratios for the 3 M_⊙ models. The red squares are stars with ‘doubtful’ Tc detection. The blue inverted triangles are stars with bolometric magnitude lower than −5.5, which should correspond to the more massive among the sample, closer to our 3 M_⊙ simulations. The black triangles are stars with bolometric magnitude higher than −5.5 and Tc detection. The uncertainties are those given in Abia et al. (2001, 2002).