Dulux Autosolv Etch Primer grey Spraypak is a Chromate free 1K etch primer. It has excellent adhesion properties over a range of substrates. It is to be used as a primer for substrates such as mild steel and aluminium. Note: The aluminium surface requires suitable preparation. It is recommended that prior to proceeding, the adhesion over aluminium be checked. The grey etch primer may be top coated with most single and two pack topcoats. It is recommended that prior to proceeding, the top coat and primer be tested for adhesion.