I've had my share of chippy edges recently and while what everyone thus far has said is true, there is more beyond that as well. Assuming that pitting is not an issue or the very useful comment made by Euclid is not your issue, it could be simply that the steel in question is not the finest. I've stated in other threads that my Hart Steel is a very chippy razor straight from the source. It performs much like you describe in that it doesn't seem to be as sharp as other razors coming off of the same stone. The bevel is set, you move on. But the next couple stones don't seem to improve the edge or its keenness much. So you stick with it until it falls apart. With a microscope you can watch the edge deteriorate. A layer or two of tape on teh spine (maybe three) will help to some degree. What I've found to be the best solution is to use tape to give it some strength, watch closely under the microscope at every grit level to ensure that the very edge is clean and straight (if not move back a grit to get it there), and stop before it starts to fall apart. Then keep moving up in grit to slowly nudge it forward. I would finish it on a either a higher grit stone than your 12K or a pasted strop. But if its like my Hart, don't expect it to hold that edge too long. All things being equal, it probably comes down to the quality of the steel. If this is a problem with all of your razors, then it probably something you are doing. If not, its probably the razor. You can grind away all day with it but you might not be able to get a decent edge on it. If my Hart wasn't a gift from my wife I would have put it up on eBay months ago.