a process for preparing a water soluble phenol - formaldehyde resole resin having improved storage stability employs a calcium compound to catalyze the condensation reaction which occurs under basic conditions . sulfamic acid is used to neutralize the resole solution , yielding a soluble calcium salt which will not settle out of the solution or clog transfer lines or spray nozzles as may a calcium salt precipitated during the neutralization . glass fiber insulation produced using a binder prepared with the aqueous resole solution shows enhanced thickness recovery and lower odor potential .