In powder coating shops, precision, cleanliness, and control of every step in the process are essential. From surface pretreatment to powder application and curing, every detail impacts the final surface quality. One often underestimated yet highly disruptive factor is silicone.
What is silicone, and why is it problematic?
Despite ongoing discussions and research, silicone contamination remains a persistent issue in production environments.
Silicones are synthetic polymers known for their water-repellent properties and resistance to high temperatures. Their unique properties make silicones extensively used across industries and everyday life, from cosmetics and lubricants to sealants. However, their invisible but effective film, which easily adheres to surfaces, reduces surface tension locally and poses a significant issue in coating environments.
Even minimal silicone contamination can lead to defects such as craters or fisheyes in coatings, reduced adhesion to the substrate, lower corrosion protection, and coating failure. Additionally, uneven textures in coatings are visually unappealing, as shown in Figure 1.
Figure 1: Fisheyes in the coating caused by silicone contamination
Sources of Silicone Contamination
Silicone can enter the coating environment from various sources:
1. Industrial lubricants and sealants: Silicones from lubricants and sealants can stick to parts or equipment.
2. Contaminated tools or packaging: Residual silicones on tools, packaging, or protective films can spread contamination.
3. Work environment: Dust containing silicone may originate from handling sealants or silicone-containing products.
4. Cosmetics and personal care products: Hair sprays, perfumes, gels, and creams (e.g. disinfectant creams) often contain silicones, which easily spread through the air and settle on surfaces.
Figure 2: Disinfectant cream containing silicone oils
How to Detect Silicone?
Silicone contamination is often invisible to the naked eye, making it challenging to identify before applying coatings. Solutions include:
- Testing methods: Specialized tests, such as FTIR (Fourier-transform infrared spectroscopy), XPS (X-ray photoelectron spectroscopy), or surface wettability measurements, can detect silicone residues.
- Preventive measures: Strict control of potential contamination sources, maintaining a clean working environment, and allowing access to the coating area only to authorized personnel.
How to Prevent Contamination?
1. Eliminating silicone products: Limit the use of cosmetics, lubricants, and other silicone-containing products in the coating environment.
2. Thorough cleaning: Regularly clean work surfaces and equipment.
3. Implementing strict rules: Train employees on the risks of silicone contamination and enforce policies like banning silicone-based hand creams in the coating area.
4. Air filtration: High-quality filtration systems can capture aerosols and dust containing silicone.
Silicone contamination is a hidden adversary that can significantly impact the quality of the final finish. Although complete elimination can be challenging, combining preventive measures, employee training, and thorough control can greatly reduce the risk. A clean work environment is fundamental to the success of any powder coating shop.
It is essential to note that not all silicones pose a threat in coating shops. Some silicones, such as special sealants for ovens, masking caps, and specific silicone lubricants, are safe for use. The key is caution – if a silicone-containing product is not confirmed to be 100 % safe, it’s better to avoid using it.
At SQI, we believe that every detail matters. For consultation or solutions to address challenges in powder coating, don’t hesitate to reach out to us. We’re here to help you achieve a flawless finish without compromise.
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