So you want to buy a photograph. Here's question 4 in the series of 5 blog posts on what to ask before buying a photograph.
Question 4. What was the print process?
Introduced in 1885, the sliver gelatin process remains the most common black and white process - light sensitive silver is bound to paper with a gelatin adhesive. Prints that use platinum, however, can have more value for their greater tonal range and rarity. Giclee prints, or archival pigment prints, are digital prints made using an inkjet printer, and should be avoided if made in large editions.