Fluorescent Penetrant MET-L-CHEK FBP-912 – Sensitivity 2 – Biodegradable penetrant used for the detection of fine cracks, porosity, and through leaks on metals, composites, synthetic materials, and some plastics. Low in sulfur and halogens, VOC free, and safe for use on all metal surfaces. It is bright yellow, smooth washing and non-gel forming, allowing a clean wash from rough surface.