The monks at Tarbat burned seaweed to create an alkaline solution in which they soaked calf skins to remove the hair and clean the hides for making parchment. Seaweed lye is not as strong as lime, which most parchment makers would have used, so the monks allowed bacteria to grow in the solution to help process the skins more efficiently–making the Tarbat technique as good if not better than the work from other monasteries at the time. Because of the bacteria, parchment produced at Tarbat would often have little pock marks in it where skins had been slightly overdone, which allowed bacteria to eat holes in them. A similar effect can be seen on many of the pages in the Book of Kells.