Abstract: A method for producing a modified gum by direct fluorination of a polymer gum. The polymer gum must be substantially uncross-linked prior to fluorination. The degree of fluorination is controlled to provide fluorinated gums having different degrees of fluorine uptake and available cross-linking sites. The resulting modified gum can be cured alone or in combination with one or more supplemental polymers to form a wide variety of elastomeric articles. Additives, such as fillers, lubricants and plasticizers may also be combined with the modified gum and added polymers during compounding and final curing.