Abstract: The present invention relates to the use of glycerol as additive for formaldehyde-free aqueous sizes based on acrylic or acrylate polymers, which are intended for the manufacture of products based on mineral wool, in order to improve the aging resistance of the products based on mineral wool that are obtained after the size has been crosslinked. The products based on mineral wool bound with such a size, which is environmentally friendly, have the same quality as products conventionally bound with a phenolic resin. The thickness recovery and flexure of the products obtained are improved.