Does PVC need primer or just glue?

For a strong bonding on PVC plastic, two things are key: prepare the surface well and use the right primer. A primer is the common, reliable choice for spraying, even though some adhesives（like Molibon no-primer PVC structural adhesive） can bond paint directly.

Why is a primer usually needed?

A primer is typically necessary because PVC materials contain plasticizers, fillers, and various modifying additives. These features result in low surface energy and high chemical resistance. Without proper surface treatment, most coatings and many adhesives cannot bond reliably to the material.

The main functions of a primer are as following:

1. Surface activation: Makes the PVC surface more active and easier to wet, creating good conditions for strong adhesion.

2. Enhanced Adhesion:  Acts as a secure middle layer, bonding PVC to the topcoat through both physical and chemical connections.

3. Ensures reliability: Prevents “false adhesion” (the bond initially seems strong but later fails), ensuring long-term durability.

How to properly paint a PVC surface?

1. Surface Cleaning: Use alcohol or a cleaner to wipe the PVC surface to remove all grease, dust and residue.

2. Roughen the surface: Gently sand the PVC surface with fine sandpaper (600–800 grit) to make it slightly textured for better adhesion.

3.Proper application: Apply a thin, even coat to completely cover the surface. Please strictly follow the recommended drying time.

(Pro tip: For optimal performance, apply primer within a temperature range of 15–30°C and relative humidity of 40–60%. Avoid application in very humid, very cold, or dusty conditions.)

For bonding rather than painting, we recommend using Molibon PVC adhesive. The PVC bonding adhesive offers fast curing, high toughness, and strong aging resistance, providing reliable bonding between a wide range of metals and engineering plastics without requiring primer.For the best results, ensure all surfaces are properly cleaned and apply the adhesive in a controlled, moderate amount.