Had to stop working on my sewing room organization today to get my block done for class Saturday and had a "Why didn't I think of this sooner?" moment. I knew my blade in my rotary cutter probably needed to be changed but couldn't remember, is it new?, have I already turned it over?, is it one of those Titanium blades that's supposed to last longer? And then it hit me! I changed the blade to the new Titanium blade and with a Sharpie fine point pen, wrote a "T" and 8/9 directly on the blade. It dried in seconds and hasn't rubbed off on my fabric. Now no more guessing!