Although bleaching of polyester is typically not necessary, it may be desired to create a very clean “base” white for tinting or brightening with an optical whitener. First, the goods must be properly scoured.
- Enter goods into a bath containing:
- 0.2 oz/gal(1.5 g/L) sodium chlorite*
- 0.2 oz/gal(1.5 g/L) sodium nitrate
- 0.3 oz/gal(1.5 g/L) acetic acid 56%
- Run goods at 200°F(93°C) for 45 minutes. 2 oz/gal(1.5 g/L) of Oxalic acid may be used in place of acetic acid when rust spots are present. After 45 minutes, drop bath and rinse well.
- In a fresh bath add 0.27 oz/gal(2.0 g/L) sodium bisulfite and .067 oz/gal(0.5 g/L) Orconol CHSA Conc™. Run at 140°F(60°C) for 20 minutes. Drop bath and rinse well.
Refer to the technical bulletins on Orco Synthrowite RBP™ or Orco Synthrowite RRP™ optical brighteners for exhaust and padding applications for increased “whiteness.” For efficiency, an “all-in-one” procedure incorporating scouring, caustic treatment, and application of optical whitener can produce a nice clean white for minimal cost. Call your nearest ORCO representative for a detailed procedure for your application and requirements.