Bubbles, poor mixing, yellowing, lack of adhesion: best practices for consistent results

When moving from artisanal creation to serial production, repeatability becomes a major challenge. Epoxy resin is a demanding material, highly sensitive to preparation conditions, humidity and temperature variations, and strict adherence to mixing ratios. For professionals producing at scale, a few recurring mistakes can lead to visible defects, material waste, or costly rework. Here is a technical guide to help secure your process and standardize the quality of your parts.

Controlling Bubbles: Prevent Them Rather Than Just Fixing Them

Common causes of bubbles:

• Mixing too fast or inaccurately

• Inclusion of damp materials (wood, insufficiently dried plant matter)

• Ambient temperature too high

• Poorly prepared or overly textured molds

Solutions:

• Slow mixing and vacuum degassing whenever volume justifies it

• Use of a pressure pot during curing

• Drying inclusions or applying surface treatments before embedding

Avoiding Curing Defects Caused by Poor Mixing

Risks:

• Sticky or soft areas

• Incompatibility during post-processing (sanding, bonding, varnishing)

• Loss of transparency or internal streaks

Best practices:

• Use a precision scale (avoid volume-based dosing)

• Strictly respect the exact ratio (e.g. 100:45, 2:1, etc.) specified in the technical data sheet or on the product label

• Always scrape the sides and bottom of the mixing container during mixing

Limiting Yellowing: Product Choice and Process Control

Common causes:

• Prolonged UV exposure

• Overheating during curing

• Inappropriate casting resin (non–UV-stable formulation)

• Poor choice of epoxy system

Recommendations:

• Choose a resin formulated with UV inhibitors and stabilized for serial production

• Avoid excessive thickness in a single pour

• Control ambient temperature and the heat released by the reaction

• Apply a protective varnish once the resin has fully cured

Ensuring Adhesion to Substrates: Systematic Surface Preparation

Frequent mistakes:

• Pouring onto greasy, dusty, or overly smooth surfaces

• Lack of sanding or adhesion primer

• Incompatibility between substrates (wood, metal, plastic, etc.) and the resin

Recommendations:

• Systematic sanding of substrates (grit 80 to 120 depending on the material)

• Dust removal and cleaning with isopropyl alcohol

• Use of a compatible adhesion primer if necessary

• Perform pull-off or adhesion tests before launching full production

In Summary: Quality in Serial Production Relies on Rigor

Producing epoxy resin parts in series requires industrial-level discipline, far beyond simple creativity. Every step—from selecting components to preparing molds—can impact the final result. The good news is that by controlling your working conditions and selecting a resin designed for professional production, quality variations can be drastically reduced.

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