This process of manufacture is why we see that papyri have fibers running horizontally on one side, and vertically on the other side. As a general rule, a papyrus scroll was rolled with the vertical fibers on the outside, which gave it the most strength. This also meant that the writing on the interior side ran parallel to the horizontal fibers, which gave the scribe a convenient guideline for writing straight lines of text.
In papyrology, the inside of a roll is generally referred to as the recto, while the outside is called the verso. Sometimes it is impossible to tell which side of a fragment of papyrus was the inside of the roll and which was the outside, but the terms recto and verso are always used to distinguish one side of a papyrus from the other.
As we have seen, a roll of papyrus was made from many individual sheets joined together. Where two sheets of papyrus were joined together is known as a kollesis. Kolleses can tell a papyrologist important information about how the roll was made and how big the original sheets were. Below is an example of a papyrus with a kollesis. Look at the large images and try to see the orientation of the fibers in the papyrus. Can you see the kollesis? There are several clues to the location of a kollesis including difference in color and damage to the papyrus, but these can also be misleading at times. In this case, both the discoloration and the crack in the papyrus reveal the location of the kollesis. Also, note that the position of the kollesis is different on the different sides of the papyrus. This is because the sheets overlapped each other by a few centimeters. The overlap was essential to forming a strong bond between sheets.
Seeing a well-made kollesis is often difficult without a microscope or magnifying lens. One of the best ways to see a kollesis is to follow a prominent horizontal fiber until it disappears. On the other hand, if you see a continuous fiber, that is proof that you are not looking at a kollesis. Although these digital images are very good, they still do not offer the level of detail visible in the original.