An aqueous concentrated borate solution comprises a quantity of boric trioxide, a borate, an aminoborate, an antifermenting agent and optionally a sequestrant or complexant additive. A highly concentrated borate solution comprises a quantity of borate, as 5-40 % of B2O3, a borate formed from a carbonate from sodium carbonate or bicarbonate, potassium carbonate or mixtures, an aminoborate formed from a borate compound an alkanolamine from ethanolamine, diethanolamine or mixtures, an anti-fermenting agent from a quaternary ammonium, isothiazolinone (optionally chlorinated) or a mixture, and optionally an additive with sequestrant or complexant properties for heavy metals or alkaline earth metals chosen from a polycarboxylic acid and/or ethylenediamine tetraacetic acid sodium salt or mixtures. An Independent claim is also included for the preparation of the borate solutions.
