History
The oil and whiting method used in the railroad industry in the early 1900s was the first recognized use of the principles of penetrants to detect cracks. The oil and whiting method used an oil solvent for cleaning followed by the application of a whiting or chalk coating, which absorbed oil from the cracks revealing their locations. Soon a dye was added to the liquid. By the 1940s, fluorescent or visible dye was added to the oil used to penetrate test objects.
Experience showed that temperature and soak time were important. This started the practice of written instructions to provide standard, uniform results. The use of written procedures has evolved, giving the ability for design engineers and manufacturers to get the high standard results from any properly trained and certified liquid penetrant testing technician.
Read more about this topic: Dye Penetrant Inspection
Famous quotes containing the word history:
“As I am, so shall I associate, and so shall I act; Caesar’s history will paint out Caesar.”
—Ralph Waldo Emerson (1803–1882)
“If you look at the 150 years of modern China’s history since the Opium Wars, then you can’t avoid the conclusion that the last 15 years are the best 15 years in China’s modern history.”
—J. Stapleton Roy (b. 1935)
“A poet’s object is not to tell what actually happened but what could or would happen either probably or inevitably.... For this reason poetry is something more scientific and serious than history, because poetry tends to give general truths while history gives particular facts.”
—Aristotle (384–323 B.C.)