An aqueous binder system including a mixture of urea-formaldehyde resin and water-dispersible polyester resin. A combination of the binder system applied to fiber insulation, a composite glass mat, glass/polyester mat, polyester mat, or substrate of a coated abrasive product. Fiber insulation, a composite glass mat, glass/polyester mat, polyester mat, or coated abrasive product with the binder system including urea-formaldehyde resin and water-dispersible polyester.