How do you know when your guides are not too sharp/not too blunt?

Is there a rule of thumb, like dragging a hook across your fingernail to test for sharpness?

After test casting a rod, I found that the guides had been scratching up the blank. I have since purchased the 3m 2" sanding disks and used the polishing grit to soften up the edges, but they still seem awfully sharp.

Any tips?

Thanks

There was a very, very in-depth article on the why and how or guide foot prep in the volume 4 #3 issue of RodMaker.

One of the best ways to tell if your guide will harm the blank is to keep a scrap piece of blank on hand, perferably one that has a painted finish, and lighty set each prepped guide on it and slide back and forth. If it scratches the blank you need to do a bit more work. Guides also need to sit perfectly flat - think about the difference in having someone in high heels step on your hand versus the same person in flat sneakers do the same thing. You don't want all the wrapping tension concentrated on one point or area.

It's okay for the feet edges to be "sharp". You want a very shallow angle both for ease of wrapping and foot flexibility, but you don't want burrs or sharp edges along the underside that dig or cut into the blank.

The Unified Wheel, which some of the sponsors now carry, is the very best thing I have yet found for removing burrs from the guide feet. Takes 2 or 3 seconds per foot for a perfect polish.

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My rule of thumb is it can cut your finger nail it well cut your blank. I just run the edge of the guide feet over a lap stone, the type used in sharping knives. This well deburr and take the knife edge off the foot.
Bob