What factor does not affect how a penetrant penetrates a surface flaw?

The penetration of a dye penetrant into surface flaws is influenced by various factors, including material temperature, surface roughness, and viscosity. Each of these factors plays a significant role in how effectively a penetrant can enter and reveal a flaw.

Material temperature is important because it can affect the viscosity of the penetrant; warmer materials may allow for better flow and penetration into cracks or voids. Surface roughness impacts the available pathways for the penetrant to enter flaws — smoother surfaces may hinder penetration compared to rougher ones that provide more entry points. Viscosity also determines how easily the penetrant can spread and flow into small cracks; a lower viscosity allows for easier penetration.

Material density, while it can influence certain characteristics of a material, does not directly affect the ability of a penetrant to enter into surface flaws. Density pertains more to the mass and volume of the material rather than how surface flaws interact with liquid penetrants. Therefore, this factor does not have a significant effect on the penetration process, unlike the other factors listed.