Silicone contamination is a huge problem in many painting and bonding applications. It’s impossible to see, hard to remove, and it creeps in unseen like a ghost. Where the harm it can cause is recognized, businesses go to great lengths to clean surfaces and exclude potential sources of contamination, probably to the point of overspending. Elsewhere, though, silicone is not seen as the culprit until one of those “Eureka Moments” strikes.
Fortunately, help is at hand. Water contact angle measurements, which provide a numerical value for surface energy, can clearly indicate when silicone is most likely present. In a “silicone detection protocol,” water contact angle can detect environmental changes and warn when problems are likely present and when action is needed.
Why Establish a Silicon Detection Protocol?
Silicone is an invisible intruder. It comes in through the air, on workers' hands and clothing, and via some of the lubricants and release agents used in manufacturing. A silicone detection protocol provides a way to identify changes in the contaminants present in the work environment.
The protocol involves setting up test locations, installing contaminant detection apparatus, and instituting a schedule of checks. This provides a baseline water contact angle measurement. Consistency in timing and frequency is essential for removing potential sources of variation, making comparisons, and detecting trends.
Water Contact Angle (WCA) measurements offer a unique advantage over techniques like FTIR and XPS. They can be conducted at various points throughout your production facility, providing early detection of potential silicone contamination. While WCA alone doesn’t definitively confirm silicone presence, exceeding a predetermined contact angle threshold is a significant indicator. To ensure accuracy, additional laboratory analysis using FTIR or XPS might be necessary.
The Impact of Silicone Contamination
Silicone is a chemically inert compound. It’s hydrophobic and acts as a lubricant, making it useful in a wide range of applications. However, these same properties make it difficult to bond to (which is why one of the biggest industrial uses is as a mold release). Consequently, if surfaces are going to be painted, lasting adhesion requires the removal of every trace of silicone. The same applies to bonding operations in activities like window assembly: any reduction of bond strength could lead to joint failure and warranty claims.
Brighton Science has helped hundreds of manufacturers resolve thousands of surface bonding and contamination problems. Our experience is that the source can often be something simple but not obvious. One example is a silicone spray used near an air-handling system; silicone in skin creams is another. We’ve learned that silicone is easily transferable yet hard to remove.
In an effort to remove surface contamination, many manufacturers have implemented plasma treatment systems. These are cost-effective and environmentally benign, but they do not remove silicone. Neither is brushing effective, as that tends to spread the contamination over a wider area. Instead, complete removal requires an aggressive solvent, something many businesses are eager to avoid.
Who Should Care About Silicone Contamination?
Any business that applies paints, adhesives, or other coatings should understand the problems silicone on material surfaces can cause. As an inert compound, silicone won’t form strong bonds, resulting in a region of weakness and risk. In assembled products - low-e glass for residential windows is an example – in-service loads can cause an adhesive bond made over silicone contamination to fail.
Surface cleanliness and preparation is a particular concern in the automotive industry as silicone can cause expensive rework and scrap. Volkswagen, in particular, has rigorous standards for surface paint readiness and goes to great lengths to prevent PWIS (Paint Wetting Impairment Substances) contamination. This extends down through their supply chain, so Tier 1 and Tier 2 manufacturers can find themselves measured against the same standards.
Avoidance Over Removal
Once a surface is contaminated with silicone, it’s extremely difficult to remove. Mechanical methods tend to spread it around, and because of its hydrophobic nature, aqueous cleaning is largely ineffective. Likewise, plasma systems will leave silicone on otherwise clean surfaces.
Given these challenges, manufacturers concerned about silicone contamination tend to use preventive methods. One approach is to subject anyone entering a sensitive area to an air blast before allowing them over a threshold. Elsewhere, employees are instructed to avoid cosmetics and other silicone-containing products (including the silicone straps of fitness bands). To avoid cross-contamination from other processes, such as molding, some manufacturers go to the expense of constructing dedicated facilities from which all silicone is excluded.
The Importance of Consistent Data Collection
Given the elusive nature of silicone and its ability to appear without warning, a contamination monitoring and detection system should be the first line of defense. Such a silicone detection protocol works by establishing a baseline for contamination in the plant. From this, any change signals a potential problem that needs further investigation.
Eliminating extraneous variables requires a consistent approach to data collection. This means establishing sampling locations, times, and frequencies. In larger enterprises where multiple plants operate identical processes, standardization enables inter-site comparisons that support further trend monitoring and detection of abnormal conditions.
Banish the Fear of Silicone Contamination
Water contact angle measurement technology from Brighton Science provides a repeatable, high-resolution method of quantifying surface energy. Surface energy predicts how an adhesive, coating, or paint will interact with the material surface, ultimately providing insight into how well a bonding procedure will work. Silicone contamination is highly likely if the measured angle exceeds a particular threshold.
The Brighton Science water contact angle technology was engineered for use in production environments and can form the basis of a silicon detection protocol. Used with the BConnect surface intelligence platform, it enables high-quality data collection and immediate transmission of the data for monitoring, tracking, and notification.
BConnect makes the invisible visible, and makes silicone detection a core competence for your organization.
BConnect can make the ability to monitor and maintain surface cleanliness, especially concerning silicone contamination, giving organizations a competitive advantage. It enables data-driven decision-making for more consistent manufacturing methods and lower costs, as well as gives customers greater confidence in your capabilities.
If you need to illuminate the invisible problem of silicone contamination, implementing a silicone detection protocol is the way to go. It will eliminate the ghosts that can otherwise haunt manufacturing and open the door to cleaner surfaces and stronger bonds. Read the full Silicone Detection Protocol news story here.
To learn more about how surface intelligence is driving the future of manufacturing, download the eBook "The Future of Manufacturing: A Guide to Intelligent Adhesive Bonding Technologies & Methodologies."
