If you write it, I will read.
Alrighty then! It's in the middle of the night again and english is my second language, so this might not turn out as understandable as I hope, but if anything is unclear, just go ahead and ask.
As I said, I have got my hands of a number of old fabric shears, or something along those lines - hard to know exactly what they were made for 50+ years after the company that made them went out of business. Just love quality tools of any kind, and if you really know how to sharpen scissors those neglected and abused $2 items might be brought back to life so they match the performance of new $20-200 ones - yes, fabric shears can easily be that expensive. But if they have the wrong kind of damage in the wrong place they may only be good for cutting paper, or sometimes they're not usable at all. Damage such as pitting from rust on the inside edge, the side that slides against the other blade is hard to correct, and bent blades (other than the normal curve that keeps the blades pressed against each other) is hard to straighten.
Quality scissors almost always has a screw as pivot, making the blade tension adjustable and making it possible to take them apart. Just getting them apart can be a challenge, but if you can't turn the screw you can't adjust tension, and it'll probably not cut well - it might be worth spending quite a bit of work getting it loose. Sometimes you have to destroy it, if you can find another screw (and preferably nut) with the same thread you can replace it, you'll probably need to regrind the head so it fits well and you might want to grind the nut fairly thin.
Cheap scissors are usually riveted together. If you need more tension it may be tightened by hammering the rivet, but be careful - there's no easy way to back it of if you go too far.
Here's a pic of one of my screw jobs.
Old screw on the right, one new screw with reground head and a nut ground to half thickness on the left and one new installed. I was in luck, swedish made scissor with standard M6 thread. Already had everything I needed.
Moving on to some actual sharpening. If the scissors are in resonable shape, you should only need to regrind the "outside edge". Match the original angle if you've still got it, you know the steel can handle it and it should cut whatever the scissor was meant for well.
If you're sharpening freehand you can rock the scissor back and forth to feel when it lies flat on the existing edge. I have made a jig to hold the scissor - just made out of scrap metal and it's far from perfect, but it is a great help when I have to grind alot - old nicked and rusty blades tend to require that.
I use a fairly coarse stone, the medium side of a coarse/medium combo - something like what I start with on a knife, so it may seem strange for knife people. The idea is that the coarse grinding marks act as teeth, grabbing on to what you're cutting, with a too fine finish it might just slide away instead.
Do remember, I'm talking about fabric and general purpose scissors here, I understand scissors for hair is usually ground quite a bit finer than this. I have never sharpened hair scissors, but I view them as a separate type of tool completely. They are very specialized to work well with hair, and as anything very specialized they probably wouldn't work very well for anything else.
The inside of the blade... Now, that's a f***ing nightmare, if that's in bad condition. On anything but possibly the cheapest scissors it is hollow ground, while it might appear flat at a quick glance it is actually concave. This ensures only the edge slides against the other blade, reducing friction and reducing problems with items (debris) getting between the blades forcing them apart so it can't cut.
If this is in good shape, all you do after sharpening the outside edge is to get rid of the wire edge. This may be done by laying a fine stone flat across the inside of the blade and drawing it across once or twice, while some people like simply forcing the blades apart so they don't touch when they close the scissor, and then knock the wire edge off when they open the scissor. I prefer using a small washita stone I have.
If the inside of the blade isn't in acceptable condition it may still be fixable, but very much more sensitive than grinding the outside edge. You
need a ride line (the line along the edge that the other blade rides against) without damage, that means no nicks or pits from rust. No matter how nice you grind the outside edge, if the ride line is uneven it will never cut well - not in hard to cut material anyway, for paper there are childrens scissors made of plastic so that shouldn't be a problem.
If you don't have to have the peak performance you may simply say f**k it and use relatively fine stones to flatten the inside of the blade a bit. You get a wider ride line, and hopefully you get rid of the damage relatively quickly. For this the scissor has to come apart, as you need to grind evenly along the blades length, including the pivot area you couldn't access if the other blade is still there. Be careful to keep the blade laying flat on the stone, if you round off the cutting edge inside it's scrap metal.
If you want the best performance you can get and have plenty of patience, a curved stone can freshen up the hollow ground side. I use a scythe stone, clamped in a bench vise. Again you need to be careful not to round of the edge, keep it laying "flat".
In this picture I only demonstrate how I do this, I would always take the scissor apart for this. The offset weight of the other blade makes it too hard to keep the blade flat on the stone otherwise. Also, narrow blades (as near the tip on pointy blades) is hard to keep flat.
The scythe stone usually has a bigger radius than the original grind, making the stone just touch the edges of the blade. It may not be ideal, but it usually gives me a damage free edge while retaining the hollow grind, and I'm happy with that for now.
Here's a picture of a blade that has had some light work with the scythe hone, and finished off quickly with a fine stone, probably the washita, to give it a very narrow kind of polished ride line for minimum friction and no unneccesary wear due to coarseness. You can still se lots of pitting (black) some distance from the edge, but where it counts there's nice, even metal with a great edge.
There may also be alot to say about the tension of the blades, the curve of the blades pushing them against each other, and many other things, but this is what I've got for now. And what I have written here is what I think and how I do things with the tools I've got. It works well for me, I can't guarantee you get the same results. I've gone down a long road of trial and error, this might help you get to the same results faster but don't expect to get there without a few errors of your own. You often learn more from messing up, than from doing things right.
