This is what I was taught to use to removed stitches when I worked at an alteration shop tearing out hems and prepping the clothing for the seamstresses.

A few years ago I found blades in a dollar store, but haven't been able to find any more since. Anyone recognize these and know what they are called or where to purchase them?

Razor blades. You can get them at Lowes or a hardware store. Probably can get them from a drug store too.

Single edge razor blades. Usually near shaving supplies and also in hardware/ painting supplies.

It's a single edge blade. You should be able to get them at a hardware store, Amazon.com has them also. Google single edge razor blade and you can find them.
They are what I used when growing up also!

Yep, that's what they are.
Edited to say that my quilt class teacher uses an electric razor, like for sideburns.

Walmart carries them too... look in any hardware section :D:D:D

If all you can find for a while are the double edged ones, you can do as I did and put a piece of tubeing on one side and tape it down. Or just put the tape on it and be careful about the sharp blade cutting through it.
But in the long run, the single edged ones are the type to get.

Ask some one married to an older man where to get one/some.

They are sold in the painting supplies as paint scrappers. I use them in the holder to scrape my smoothtop range. The surgical blade seam rippers are thinner and sharper and work the same as the razor blades and cost less.

Single edge blades....any hardware store will carry them.

Harbor freight in the painting supply.