Does this look like a loose strand of string?

It's a good start, but I see a few tweaks you could make that could really put some life in it. I hope you don't mind that I did a few edits -- it was confusing to try and explain it clearly without a visual. 9w9;

But to sum it up:

• Thinning out some corner pixels, especially inside curves, can improve the rounded effect. Basically, having a consistent width in terms of pixel count actually makes a bent line look bulkier in places, because the square pixels don't translate well to the real-life geometry of curved shapes. :B
• Having the light come from a constant angle makes a huge difference! Notice that the shine isn't a continuous line; it can be broken up, especially around curves, to create the effect that it's following the shape of the string. You can see this on the top left of pictures 3-5; the shine breaks in a couple of places, but it isn't really noticeable.
• The last one's largely a matter of taste, but I feel like a more muted blue might look "stringier" (since rough/soft surfaces tend to have a dull appearance). Of course it also depends on exactly what type of string it is.

My tweaks: https://drive.google.com/file/d/1Ya5T7AhKlyy0Bdjltd6Vi49zKczUo_jc/view?…