No. While simple pen ink will likely not damage webbing directly, there is a safety risk that the ink contains a substance that could degrade the webbing and make it to lose strength. There are other factors to consider when marking webbing. Pen tips, brushes, or other writing devices may damage webbing if excess pressure is used, or may grind in dirt or corrosive substances into webbing. Ink or paint may also cover up damage to webbing, making it difficult to notice during equipment inspection. FALL SAFE®
provides customizable patches on harnesses that may be written on, but no webbing should ever be altered in any way.