The Exothermic Reaction Disaster
This is a classic example of how a minor mistake can lead to disastrous results.
An apprentice applicator had joined the company just two weeks earlier. Due to manpower shortage, the project coordinator had no choice but to send this green recruit to the site. His decision was reinforced by the fact that the application appeared very simple—a standard 100% non-volatile epoxy paint was to be applied on an already prepared surface.
The project coordinator took on the task of training (😀) the recruit. Using a demonstration kit of approximately 150 grams, he showed how the pre-measured quantities of resin and hardener should be mixed, then kept aside for a couple of minutes so that air bubbles entrapped during mixing could rise to the surface and escape into the atmosphere. He also demonstrated the application method—cross-brushing, first vertically and then horizontally—along with the finishing touch.
He asked the apprentice whether he had understood everything and if he felt confident to go to the site. Eager to prove his capability, the apprentice replied affirmatively and proceeded to the site.
At the site, epoxy paint was supplied to the customer in a 20 kg kit. The green recruit simply mixed the pre-measured quantities of resin and hardener, stirred them well, and kept the mixture aside for the entrapped air bubbles to rise and escape.
WHAT HE DID NOT KNOW—BECAUSE HIS INSTRUCTOR FORGOT TO TELL HIM—WAS THAT THE MIXING OF RESIN AND HARDENER IS AN EXOTHERMIC REACTION.
This reaction is hardly noticeable in small quantities, but the heat generated increases in geometric progression, not arithmetic, as the quantity increases.
Soon, bubbles started rising vigorously to the surface, which the applicator mistook for entrapped air bubbles. In reality, due to the large quantity being mixed, a significant amount of heat was generated, resulting in frothing of the product.
Within moments, the froth grew to almost three times the size of the container, overflowed, spilled onto the beautifully prepared surface on which the container was placed, and completely ruined it—solidifying right there. Due to the intense heat, it was impossible to go near the container, move it, or take any corrective action. The applicator stood there helplessly, horrified by the unfolding scenario.
To make matters worse, the incident occurred in an area with acid fumes. The heat intensified the acid vapours, causing everyone nearby to start coughing. Since this was a very large corporation with extremely strict safety norms, the issue escalated right up to the Chairman level, and our Chairman had to somehow manage the situation.
A SIMPLE OVERSIGHT BY THE TRAINER—FAILURE TO EMPHASIZE THE IMPORTANCE OF EXOTHERMIC REACTION IN RELATION TO MIX QUANTITY—RESULTED IN AN UNFORGETTABLE AND SHAMEFUL INCIDENT.
The Critical Lesson
Understanding Exothermic Reactions: When working with epoxy systems, the heat generated during the resin-hardener reaction increases exponentially with quantity, not linearly.
Mix Size Matters: What works safely in a 150g demonstration kit can become dangerous at 20kg scale without proper precautions.
Complete Training: Never assume that demonstrating a process is sufficient. Always explain the underlying chemistry and scale-related considerations.
This incident reinforced a crucial principle: training must go beyond demonstration. It must include understanding the science, recognizing potential hazards, and knowing how process parameters change with scale. A few extra minutes spent on comprehensive training could have prevented this embarrassing and costly disaster.
— Mr. Chandrashekhar Pathak
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