Palmitic is a saturated fatty acid that contributes a long shelf life, a hard bar, and stable creamy lather. Oils with a high profile in palmitic fatty acid add this to increase stability in the bar. The lather from the palmitic oils create a dense slick lather, or minimal lather with tiny smooth bubbles. Popular soap making oils with a palmitic profile are, of course palm shortening, palm oils, and palm kernel oil, but there are many others as well. Animal fats are high in a palmitic profile, such as lard and the family of tallow. In plant based oils palmitic profiles include Cocoa butter (an alternative to palm oil). The average percentage of palmitic acid in the favorite soap recipes of soap makers polled rounds in at 15%,. Most recipes measure at 10% to 20% palmitic acid. This is not a hard rule. Some of my favorite recipe include 35%.
Making piped decorations high in palmitic type oils helps to contribute to solid shapes for flowers and designs. The consequence of too much palmitic oil is that the trace can thicken quickly so piped designs have to be timed quickly to keep the recipe from setting up too fast.