How to create Treated Silk Fibres
Treated Silk Fibres are used in making the Blessed Fishing Rod recipe with Fishing. You can either use that rod for actually fishing (not recommended as it breaks easily) or in the Luclin Earring of Solstice Quest. In order to make this item you'll first need to make Dragon Egg Oil with Brewing. It's a simple combine but takes an item which you need to forage from Western Wastes or Temple of Veeshan, Dragon Egg.
Aside from the Dragon Egg Oil you'll also need a Silk Cord which is made from Spiderling Silk.
Treated Silk Fibres (Trivial 150)
Once you have all of the required ingredients, combine them together in a Loom or Sewing Kit.