I sowed some spandex around this mask and its stitching is really good, but I'm a perfectionist and seeing little strings every now and then drives me crazy. Is there something I could put on it to make the stitching sealed? Like superglue or something?

I'm scared superglue will melt the cloth.

Try clear nailpolish

Go to a craft store and look for GS Hypo Cement. It's a liquid that dries clear. I use it for reinforcing knots when beading. I just checked the box and it doesn't say anything about not using it on fabric.

Thank you both!