First, what is PET and PBT?
- PET is cheaper and widely usage in paint brush industries.
- PBT is cheaper to replace nylon bristle. More soft than PET. Noramlly used in paint brushes/makeup brushes/toothbrushes ect.
When painting, longer taper can absorbtion more paint. That's why need tapered filament.
When doing the chemical taper, need around 15-30% PBT to proceed, this is called PET taper. More stiff but with elastic for wall painting.
And more PBT will creat more soft and longer taper.