This study investigates how cleaning-agent selection influences the detectability of surface discontinuities in welded joints during Type II dye penetrant testing. An exploratory single-factor test compared four cleaners, one commercial reference, and three alternatives. Weld coupons containing both simulated and real defects were inspected to evaluate test sensitivity and indication sharpness. Results show that the chosen cleaner significantly affects the visibility of cracks and porosity by controlling both excess-penetrant removal and liquid retention within flaws. Eco-friendly, low volatility formulations proved feasible without compromising inspection reliability or ASTM E165/E165M-23 compliance. Recommendations for industrial practice highlight the need for qualification trials and operator training when replacing traditional solvents with safer, more sustainable alternatives. Adopting the optimal cleaner can enhance nondestructive weld testing while promoting environmental protection and occupational health.