为什么信笺纸是黄色的？

The legal pad got its start with Thomas Holley in 1888. Holley was 24 and working at a paper mill in Holyoke, Massachusetts. Every day, he and his co-workers threw out a lot of scrap pieces, called sortings, left over from cutting paper into the right sized sheets. He knew there had to be a use for them and eventually hit on the idea of cutting the sortings to the same size and binding them into small notepads. Since the paper was essentially trash to the mill, they could sell the pads at low prices.

The first few batches of pads sold so well that Holley quit his job at the mill and started his own company--Ampad, or the American Pad and Paper Company--to collect scraps from the local mills and manufacture and sell his pads. His company still exists, and they still manufacture notepads in a variety of sizes and shapes. And colors.

The pads that Holley made probably weren't yellow, and that isn't the only color they come in today. The only thing that technically sets the legal pad apart from every other notepad is the 1.25-inch, left-side "down lines," or margins. According to a historical deep-dive on legal pads in a 2005 issue of Legal Affairs magazine, Holley added these lines "in the early 1900s at the request of a local judge who was looking for space to comment on his own notes."

Still, when most people think legal pad, they think of the classic yellow paper and blue lines. The true origin of the yellow hue is actually a mystery. As far as we know, Holley's pads were white pads, and dyeing them yellow would have upped his cost and ruined his business plan.

There are a few competing hypotheses about how the pads came to be yellow later on, but none can be verified and no one seems to know when the pads first came out in color. One origin story suggests that yellow contrasted well against black ink without glare, making text easier to read. Or, that from a psychological perspective, "yellow is an excellent color for stimulating mental activity," so writing on yellow notepads could boost your creativity or clarity.

Another possibility is that Holley or his successors eventually decided to dye the paper to hide the fact that the pads were made from scraps of varying age and quality, and yellow was the cheapest or most readily available dye at the time.