This is a UP0741 Aero Acid #8 1K Etch Primer. U-Pol Acid #8 1K Etch Primer. Get your paint to stick to difficult substrates. Is a ready-to-use aerosol etch primer. It is used for priming bare metal surfaces, this promotes adhesion of paint & prevents steel from rusting. Acid # 8 is chromate-free. Typical applications are over-rub through areas prior to painting, or new bare metal panels or over bare seams before sealant is applied fast drying.