ZChek Solvent Removable Penetrant is a product used for non-destructive testing (NDT), specifically for liquid penetrant inspection (LPI). It is a visible red dye penetrant that is formulated to find surface-breaking flaws such as cracks, porosity, and lack of fusion in materials like welds, castings, and forgings. The product is non-halogenated, which makes it safe to use on all metals.