What causes hairiness in threads?

Check working condition and parts of sewing machines (i.e. hook, bobbin case, throat plate, needle tip, sharp thread guide) plus thread quality and material thickness.

I have untwisted thread, why is this and how can I prevent it?

How do I reduce back staining problems?

Back staining is a common issue in denim manufacturing. It is specially visible when light contrast thread shades are used. Indigo dyestuff from fabric contaminates the surface of the thread resulting in back staining. Ensure correct wash process is used.