Additive OF Ester Borchers Moisture scavenger Polyurethane Additive OF is a stabilizer for polyurethane coatings. Additive OF is a water-clear liquid with an ester-like odor which is used to bind moisture in polyurethane coatings. Additive OF is compatible with Desmodur® and Desmophen® products. However, storage stability is not assured in all combinations. Additive OF is used to bind moisture in two-component systems. Its suitability for individual applications must be tested carefully. It is used in polyurethane coatings. Water-clear liquid with an ester-like odor. Used to bind moisture in polyurethane coatings.