Abstract: The present disclosure relates to writing instruments which are charged with a water-based ink composition comprising trimethylolpropane. The present disclosure also relates to a solid ink composition which may be used to refill the rechargeable writing instrument. The solid ink composition itself is a concentrate of the water-based ink composition and can be diluted by the user with e.g. water to produce the aforementioned water-based ink composition. The present disclosure further relates to methods of producing the solid ink composition and the water-based ink composition as well as to various uses thereof.