Membrane Marking Pen Membrane marking pen The membrane marking pen is a highxylene, felttipped marker that permanently writes on nitrocellulose and nylon membranes used in standard transfer procedures. For marking nitrocellulose and nylon transfers. This indispensable tool ensures easy identification and orientation of gel transfers, colony and plaque lifts, and Western blots, even when the membrane is damp. It is compatible with hybridization and incubation buffers. An excellent marker for keeping records of transfers.