SEM 42003 Black High Build Primer – 16 oz Aerosol | Elastomeric Primer for Steel, Aluminum, Plastic & Fiberglass

Overview

SEM 42003 Black High Build Primer is an elastomeric acrylic primer designed to prime automotive metal, aluminum, urethane, and plastics. This high-build coating creates a thick, smooth base that helps even out surface variations and provides a solid foundation for color coats. The film remains flexible, which can help accommodate substrate movement and support a durable topcoat finish over time.

Key specs at a glance

• Applications: Steel, Aluminum, Plastic, SMC, Fiberglass
• Packaging: 16 oz aerosol can
• Coverage: 11 sq ft at 2 mil DFT
• Coats: 2-3 medium wet
• Dry time: approx 1 hour; flash time between coats: 5-10 minutes

How to use for best results

• Shake well before use and apply in smooth, even passes to build up to 2-3 coats
• Allow about 1 hour of dry time between coats for proper film formation
• Maintain proper ventilation and follow safety guidelines during application
• Prepare the surface thoroughly and follow with compatible topcoats after curing

Real-life scenarios

Whether refreshing automotive panels, treating repainted metal frames, or prepping new plastic or fiberglass parts, SEM 42003 offers a dependable base layer. The elastomeric film provides a flexible foundation that can help create a uniform surface for subsequent coatings, reducing the likelihood of visible imperfections as the project progresses.

Why choose SEM 42003

As a trusted name in surface preparation, SEM’s high-build primer offers a versatile option for diverse substrates. While results depend on proper surface prep and compatible topcoats, this primer balances build, adhesion, and a manageable dry cycle to keep projects moving forward.