What year was the oil and whiting LPI method used?

• A. the late 19th century until about 1940
• B. the 1950s to 1960s
• C. the 1800s to 1850s
• D. the 1920s to 1930s

Answer: (A)

Oil-and-whiting is an early form of liquid penetrant inspection that dates back to the late 1800s and remained in use through roughly 1940. It uses a penetrating oil to enter surface flaws and a white powder (whiting) as the developer to reveal these traces when examined visually. This approach was simple, inexpensive, and didn’t require specialized equipment, which is why it persisted for many decades. By around the 1940s, newer penetrants—such as dye penetrants and later fluorescent penetrants—offered greater sensitivity and easier interpretation, leading to the decline of the oil-and-whiting method.