Few issues in plastics processing are as sneaky or costly as carbon contamination. One day, your operation runs clean—but after a shutdown or changeover, you start seeing black specks, streaks, or gels that derail production. What causes this? And more importantly, how can you prevent it?
The Hidden Sources of Carbon Contamination
Carbon contamination often begins quietly. Excessive barrel heat, long resin residence times, or improperly controlled screw speed can cause resins—or additives—to degrade. Over time, these residues settle in hard-to-reach spots like vent areas, breaker plates, or around the trailing edges of screw flights.
Sometimes the contamination shows up right at start-up—leftover degraded resin from the previous run may have carbonized overnight. Once that happens, it’s more than mere scrap; you’re eating into profits, extending downtime, and risking missed delivery windows.
Why Traditional Cleaning Falls Short
Many processors default to running virgin resin or manual cleaning when they spot black or brown spots. But production resins aren’t cleaners—residue layers can continue to plate onto metal surfaces and appear later as stubborn black specks. Manual methods like wire brushes or torches can further damage equipment and pose safety risks.
The Smarter Alternative: Purging Compounds
Enter Asaclean® purging compounds—engineered specifically for breaking down and removing carbon build-up across the machine interior.
For active contamination, grades like EX deliver aggressive scrubbing power. EX is glass-filled and lifts carbon deposits efficiently—even in tough areas—allowing you to resume production cleanly and safely.
For difficult hot runners, extrusion dies, or hard-to-reach spots, chemical purging compounds shine. They rely on heat and controlled expansion to penetrate areas that mechanical purging compounds can’t reach, such as wide dies or accumulator heads.
Prevention Is the Best Medicine
Even with powerful cleaners on hand, the best defense against carbon contamination is routine preventive purging. Right after finishing a run—or before a shutdown—use an unfilled purge grade (like U Grade) to seal the system. This prevents oxygen from entering and stops degradation before it starts.
Establishing a purge schedule between color/material changes, at shift ends, or in extended runs creates a healthier processing rhythm. You'll avoid bulk contamination, reduce scrap, and keep changeovers smooth.
Real Impact: Cleaner Machines, Lower Costs
On average, Asaclean® customers report a 64% reduction in scrap caused by carbon contamination. Dirty machines don’t just create defects—they drive up maintenance costs, extend labor hours, and degrade part quality. Switching to a strategic purge approach flips the script: cleaner runs, safer equipment, and production that stays on schedule.
Final Thoughts
Carbon contamination is a serious challenge, but it doesn’t need to be paralyzing. By diagnosing root causes (heat, residence time, shutdowns) and applying the right purge strategy—EX Grade for reactive cleaning, chemical compounds for thorough penetration, and preventive sealing during downtime—you turn chewing on problems into chopping them off at the root.
Ready to see the difference Asaclean® can make in your production? Request a free sample today and experience how our purging compounds can enhance your color change efficiency, reduce waste, and improve your manufacturing process. Our team of experts is here to guide you through the process and help you achieve the best results. Contact us now to get started!
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