Promoters and Accelerators In The Composite Materials Industry: What They Are, What They Do, And Why They Matter To You And Your Business
Monday, May 05, 2025
Why Promoters and Accelerators Matter In Composite Manufacturing
In composite manufacturing, speed, consistency, and quality are everything. Whether you're building boats, bridges, or automotive parts, curing control is what separates a smooth, efficient operation from one full of rework, waste, and production headaches.
While initiators (or catalysts) kick off the polymerization process, promoters and accelerators are the real tools that give you control—control over cure speed, exotherm, gel time, and ultimately the physical performance of your product. They are the fine-tuners of the curing process, allowing you to dial in exactly the kind of behavior you want from your resin system.
When you understand how to use these additives correctly—and which ones are right for your specific application—you can improve throughput, reduce defects, lower costs, and make your entire operation more predictable and efficient.
In this article, we’ll take a deep dive into what promoters and accelerators are, how they work with initiators like MEKP, CHP, and BPO, and how Orca Composites can help you optimize every step of the process.
Understanding Promoters and Accelerators: The Key To Cure Control
Initiators are like the ignition switch in your resin system—they start the reaction. But once that reaction is underway, promoters and accelerators act like the throttle and steering wheel, determining how fast you get to full cure, how much heat is generated, and what kind of performance characteristics your final part will exhibit.
These additives work by modifying the rate at which the initiator breaks down into free radicals. The more efficient that breakdown, the faster (or slower) your cure. And with that control comes opportunity—faster cycles, longer working times, safer processing, and better cosmetic outcomes.
Let’s break it down further.
Common Promoters and Accelerators Used in Composites—and When To Use Them
Cobalt Naphthenate (CoNAP):
- What It Is: A cobalt-based metal salt, typically provided as a 6% or 12% active solution in an organic carrier solvent.
- Primary Role: Acts as a promoter that enhances the decomposition of organic peroxides like MEKP and CHP.
- Where It Shines: Room-temperature curing of polyester and vinyl ester systems.
- Why It Matters: CoNAP shortens gel time and speeds up cure by boosting free radical formation. Without it, most standard MEKP systems wouldn't fully cure under ambient conditions.
- Pro Tip: Using too much CoNAP can lead to color issues (cobalt is purple) or overly aggressive cure behavior. Proper balance with initiator and accelerator is key.
N,N-Dimethylaniline (DMA):
- What It Is: An aromatic amine used as an accelerator, typically 100% active but also available in 10% diluted versions.
- Primary Role: Works alongside CoNAP to speed up cure when using MEKP or CHP. Also effective as a standalone accelerator with BPO.
- Best For: Fast, efficient room-temp curing systems where short gel times are desired.
- Why It Matters: DMA allows for rapid processing in production environments, making it ideal for putties, laminates, and fast-turnaround parts.
- Pro Tip: DMA can oxidize and darken over time—keep it sealed, out of sunlight, and in cool conditions for maximum shelf life.
N,N-Diethylaniline (DEA):
- What It Is: A cousin of DMA with two ethyl groups instead of methyl groups—providing a slower reaction profile.
- Primary Role: Same as DMA, but used when you want to extend gel time and/or reduce exotherm in highly reactive systems.
- Best For: Large pours, thick laminates, or parts where excessive heat during cure is a concern.
- Why It Matters: DEA slows things down just enough to control runaway exotherm and gives a more controlled, cosmetic cure—without compromising final properties.
- Pro Tip: DEA is marginally safer to work with than DMA, which may be important for operations focused on long-term health and safety.
Best Practices For Using Promoters and Accelerators
Getting the cure dialed in isn’t just about using the right ingredients—it’s about using them correctly. These additives can be incredibly powerful tools, but if mixed improperly or added in the wrong sequence, they can backfire—causing gel coat discoloration, incomplete cure, or worse, dangerous reactions.
Here’s how to use them right:
Accurate Measurement and Mixing:
- Always measure your additives by weight or volume with calibrated tools.
- Add accelerators like DMA or DEA slowly while mixing to avoid hotspots.
- NEVER pre-mix promoters (like CoNAP) directly with initiators or accelerators—that's a serious fire and explosion risk.
Maintain a Controlled Environment:
- Curing performance can shift dramatically with temperature and humidity.
- Keep your shop between 65–80°F with stable humidity for predictable results.
- Avoid curing under direct sunlight or near cold drafts—both can lead to uneven curing and cosmetic issues.
Follow Proper Storage Guidelines:
- Keep DMA and DEA in sealed containers, in a dark, cool place.
- CoNAP should be stored away from initiators, heat, and strong oxidizers.
- Label everything clearly and store according to SDS guidance.
How Orca Composites Helps You Get Curing Just Right
At Orca Composites, we don’t just manufacture composites—we help you build better processes, better products, and better businesses.
Here’s how we support your operation when it comes to promoters and accelerators:
- Product Selection Made Easy: We carry multiple options to suit your exact needs. Need a slower reaction for large parts? We’ve got you. Want lightning-fast cures for high-volume production? No problem.
- Technical Support That Actually Helps: Our team understands the chemistry and the real-world challenges of production. We’ll help you balance initiator/promoter/accelerator ratios for optimal gel time, cure window, and part performance.
- Emphasis On Safety & Compliance: We provide detailed SDSs, storage recommendations, and staff training materials to help your team handle all additives safely and legally.
Key Takeaways & Next Steps: How To Gain More Control Over Your Cure Process
Promoters and accelerators give you the power to fine-tune your curing behavior, from pot life to exotherm to final strength. They’re critical tools for any composites operation that values consistency, speed, and safety.
Key Takeaways:
- Promoters (like CoNAP) help initiators work at room temperature—critical for curing polyester and vinyl ester systems.
- Accelerators (like DMA and DEA) give you control over how fast or slow the cure progresses.
- Proper ratios, mixing, and storage are essential for safe and effective use.
- Partner with Orca Composites for expert guidance, premium materials, and real-world solutions that boost performance, profit and help you to realize your company’s objectives in a more efficient and expedited manner.
In our next article, we’ll dig into Inhibitors—how to delay or slow down cure times for better working windows, shelf stability, and specialty applications.
Need help dialing in your cure system? Contact Orca Composites today at sales@orcacomposites.com to get started. Let’s make your next batch your best batch.
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