Liquid Penetrant is one of the oldest and most reliable methods when seeking to detect discontinuities open to the surface on a wide array of materials. Hi-Tech Testing utilizes both visible (color-contrast) and fluorescent dyes as the application dictates and based upon other factors the penetrant may be either solvent removable or water washable. When performed in accordance with a properly prepared procedure, liquid penetrant is capable of detecting very fine surface discontinuities not visible to the naked eye.