Funny that I've never actually thought about the question. Nor have I ever looked it up. When I started reading sewing blogs, at some point someone mentioned what a seam ripper looked like. When I first needed to rip a seam, I grabbed the one that came with my sewing machine, proceeded to insert it into the seam, found out by trial and error that the blade wasn't the side of the pointy bit, but the area between the two points, and ripped the seam. After a while, I found out that there are other methods, that didn't produce as many shreds of thread. And at some point, I stumbled over the method I mostly use now (at least with stable fabrics, and ripping out a straight stitch), as it's delightfully fast and almost fun to use. It's actually more like unravelling than seam ripping. I'm going to describe it to you in a moment, and maybe you don't know it yet and it'll make seam-ripping more fun to you. :)
Ok, sorry for the rambling, I'm just a bit excited.
I'm not a big fan of unsewing, except maybe when I take apart an RTW garment for refashioning/fabric harvesting. That's fun for some reason. ;) I usually cut the seams off, especially in knit garments, because they are almost always overlocked, and who wants to deal with that many shreds of thread?? But hems are a different story. Sometimes you need the hem allowance because there's not enough fabric otherwise. And usually, it's a coverstitched hem.
So. I just found out that my usual method of seam ripping/unravelling works with coverstitched seams. For some reason this really makes me happy, because it took almost no time to open the hem of a dress and its sleeves. If you already know this method, feel free to giggle condescendingly at my exitement.
So this is how I do it:
So, did you know about this method of seam ripping? Do you know the "official" one (or at least the one with the most google results)? Which method do you use?