PPG - Sigma Etch/ T Wash is a phosphoric acid based etching solution for treating new unweathered galvanised surfaces prior to painting.

Features

• For pretreatment of new galvanized steel where blasting or abrasion is not possible.
• May be overcoated with a wide rang of protective coating systems.
• May be used to give adhesion of high-temperature coatings to new galvanized steel.
• Changes color on application from blueto black to indicate the effectiveness of primary pretreatment.
• Meets the requirements of British Rail's 'T-wash' Solution
• Not recommended for immersed conditions.

Instructions For Use

• Mix thoroughly before application
  
• Over-application will produce a dense black powdery layer which is unsuitable for the application of top coats.
• Such areas will require either abrading or washing to remove powdery deposits otherwise the adhesion of topcoats will be adversely affected.

Surface Preparation

• Galvanized surfaces are variable and the preferred method of treatment is to lightly sweep blast followed by degreasing and cleaning.
  
• Remove all rust, dirt, moisture, grease or other contaminants from the surface.
• Any traces of soluble zinc salts should be removed by abrading and washing.
• Washed with fresh water to remove emulsified residues, dirt and other contaminants.
• Surfaces which following application do not uniformly blacken, indicate insufficent primary surface preparation and these should be re-prepared by abrading.

Application Method

Brush recommended, apply at 15.0m²/l (611ft²/US gal)

Roller is suitable

Recommended thinner

•     No extra thinner is necessary

Note:

    If however application results in a black powdery surface then Sigma Etch can be diluted with tap water