I use a small sharpening stone I got at a local knife maker/sharpener that is commonly used for fish hooks and the like. It is about the size of a pen, retracts into a plastic case and cost no more than a few dollars...it is also great for taking the burrs out of pins after I sew over them (though I really try NOT to do that!) and smooths away tiny chips on the edges of crystal and glassware. I think the seam rippers I have were given to me in 6th grade! I am well beyond that now, having just turned 49, so I think this method works!