Abstract: The invention provides a process which makes it possible to regulate the degree of oxidation-reduction of a glass during its production.According to the invention, which relates to glasses intended to be transformed into continuous or staple fibers containing at most about 1% by weight of Fe.sub.2 O.sub.3, the degree of oxidation of the glass is obtained by incorporating in the mixture of vitrifiable products at least two oxidizing agents, one of them being an inorganic nitrate, the other being, according to preference, an oxidized compound of manganese in which the oxidation state of the manganese is greater than 2, potassium dichromate and/or ceric oxide.The invention particularly favors the recycling of waste from products with a glass fiber base in the vitrifiable mixture.