Context: Bitumen was used in early photographic technology. In 1826 or 1827, it was used by French scientist Joseph Nicéphore Niépce to make the oldest surviving photograph from nature. The bitumen was thinly coated onto a pewter plate which was then exposed in a camera. Exposure to light hardened the bitumen and made it insoluble, so that when it was subsequently rinsed with a solvent only the sufficiently light-struck areas remained. Many hours of exposure in the camera were required, making bitumen impractical for ordinary photography, but from the 1850s to the 1920s it was in common use as a photoresist in the production of printing plates for various photomechanical printing processes.[not in citation given]

Question: In what early technology was bitumen used?
Answer: photographic

Question: What photographer used bitumen to make the earliest extant nature picture?
Answer: Joseph Nicéphore Niépce

Question: What feature of bitumen use in photography made it impractical?
Answer: hours of exposure

Question: During what period was bitumen used in printing processes?
Answer: 1850s to the 1920s

Question: Exposure to what natural element was necessary for early photographic plates?
Answer: light

Question: What was used in early photomechanical technology?
Answer: Unanswerable

Question: What did spanish scientist Joseph Nicéphore Niépce use to make the oldest surviving photograph?
Answer: Unanswerable

Question: Exposure to darkness did what to the bitumen and also made it insoluble? 
Answer: Unanswerable

Question: What did exposure to light harden and make soluble?
Answer: Unanswerable

Question: When did the Spanish scientist use bitumen to make a photograph from nature?
Answer: Unanswerable