Evaluated Alternative Sciessent Curb® Fluorine-Free Durable Water Repellent Sciessent Curb® is a fluorine free durable water repellent for textiles that is made without perfluorinated chemicals or fluorinated silicones. It is certified by Oeko-Tex, bluesign and GOTS and its water repellent performance and durability is equivalent to C6 PFC technology. In addition, Curb is a highly biodegradable chemical. Curb® was tested using the OECD 301B method. The results of this testing showed that Curb® is 79.1% biodegradable. This is very close to the maximum of 79.8%, and is considered rapidly biodegradable.