Not Good for Stamping
No matter how many times you stamp something, the edges of the letters don't come out crisp. If you're buying these for tracing, these might be okay, because it will stamp the general idea, and then you trace over it. But for general stamping, I wouldn't recommend. I tried using Distress ink and Versamark (for embossing), so I'm fairly certain it's not the ink that causing the problem.