AbstractMotivated by recent theoretical arguments that expanding strings can be regarded as having a temperature that is inversely proportional to the proper time, $$\tau $$ τ , we investigate the consequences of adding a term $$\propto 1/\tau $$ ∝ 1 / τ to the string tension in the Lund string-hadronization model. The lattice value for the tension, $$\kappa _0 \sim 0.18\,{\mathrm {GeV}}^2\sim 0.9\,{\mathrm {GeV}}/{\mathrm {fm}}$$ κ 0 ∼ 0.18 GeV 2 ∼ 0.9 GeV / fm , is then interpreted as the late-time/equilibrium limit. A generic prediction of this type of model is that early string breaks should be associated with higher strangeness (and baryon) fractions and higher fragmentation $$\langle p_\perp \rangle $$ ⟨ p ⊥ ⟩ values. It should be possible to use archival ee data sets to provide model-independent constraints on this type of scenario, and we propose a few simple key measurements to do so.