5 Critical Mistakes in Storage and Handling of Paints and Inks That Jeopardize Quality and Safety

Photo: Patrick Hendry / Unsplash

Coatings and inks are sensitive chemical systems whose properties can be significantly affected by storage and handling conditions. Even minor deviations from recommended procedures—whether in temperature, humidity, or the way containers are handled—can lead to irreversible changes such as sedimentation, coagulation, loss of viscosity, or even spontaneous combustion. For manufacturers and processors, it is therefore crucial to adhere to the supplier’s technical specifications and general principles of safe storage. In this article, we focus on five common mistakes that can compromise the quality of raw materials and the safety of workers, and we show how to effectively prevent them.

1. Failure to maintain temperature conditions: How heat and cold alter the properties of coatings

Temperature is one of the most critical factors affecting the stability and performance of paints and inks. Excessively high temperatures accelerate chemical reactions in the material, which can lead to premature drying, increased viscosity, or even polymer degradation. For example, dispersion paints stored at temperatures above 30 °C often lose their rheological properties, complicating their application and impairing the final appearance of the coating. Conversely, low temperatures, especially below freezing, can cause component separation, crystallization, or irreversible changes in consistency. Water-based systems are particularly sensitive in this regard—frost can lead to irreversible damage to the emulsion.

The recommended temperature range for most paints is between 5 °C and 25 °C, although some special products (e.g., UV inks or epoxy systems) require even stricter control. Storage areas should be equipped with air conditioning or heating with a thermostat and regularly monitored. It is also important to avoid direct sunlight, which can locally increase the temperature in containers. When handling materials in extreme conditions (e.g., in winter), it is advisable to let them acclimatize in a controlled environment for at least 24 hours before use.

2. Improper Sealing of Containers: Why Even a Small Leak Causes Major Problems

Even a seemingly minor container leak can have fatal consequences for the quality of paints and inks. Contact with ambient air leads to oxidation, solvent evaporation, or moisture absorption, resulting in surface skin formation, viscosity changes, or loss of adhesive properties. In two-component systems, premature exposure to moisture can trigger unwanted polymerization before the components are mixed. For example, polyurethane coatings are extremely sensitive to moisture—even a small amount of water vapor can cause bubbling or insufficient curing.

Prevention is based on using original containers with high-quality seals and regularly inspecting closures. After each withdrawal, the container must be tightly sealed and, if necessary, covered with film to ensure airtightness. For large containers (e.g., drums), it is advisable to use inert gases (nitrogen) to displace the air above the liquid level. It is also important to always store containers in an upright position to minimize the risk of leakage through the seal. When transferring materials, work quickly and use clean, dry tools to prevent contamination.

Photo: Ricardo Gomez Angel / Unsplash

3. Ignoring material compatibility: When chemistry turns against you

Improper combination of materials during storage or handling can lead to chemical reactions with unpredictable consequences. For example, contact between acidic components (e.g., catalysts) and alkaline coatings may cause gelation or the formation of undesirable salts. Similarly, some solvents can disrupt the structure of plastic containers, leading to cracking or the release of impurities into the material. In inks, pigment precipitation or changes in color shade may occur upon contact with incompatible additives.

Before storage or handling, it is essential to verify the compatibility of all materials according to safety data sheets and technical specifications. As a general rule, aggressive chemicals (acids, alkalis, strong solvents) should be stored separately from other products. Metal containers are suitable for most organic solvents, while plastic packaging (e.g., HDPE) is preferred for water-based systems. When transferring or mixing, only approved containers and tools that do not contain residues of previous materials should be used. In case of doubt, it is advisable to perform a small-scale test mix and monitor any changes.

4. Neglecting Labeling and Traceability: How to Lose Track of Hundreds of Liters of Material

In an industrial environment where dozens of different coatings and inks are handled, precise labeling and traceability are crucial for ensuring quality and safety. Missing or incorrect labels can lead to material mix-ups, resulting in poor-quality coatings, complaints, or even safety incidents. For example, using the wrong hardener in an epoxy system can cause insufficient curing or toxicity of the final coating. According to REACH and CLP regulations, each container must be labeled with the product name, warning symbols, safe handling instructions, and expiration date.

The labeling system should include not only basic information but also data on the batch, opening date, and any modifications (e.g., dilution). It is advisable to use color codes or barcodes for quick identification. Electronic warehouse management systems can significantly facilitate traceability and minimize the risk of errors. It is also important to regularly check the currency of labels and remove outdated or damaged ones. When transferring materials into smaller containers, all information from the original packaging, including safety instructions, must be immediately transferred.

Photo: American Public Power Association / Unsplash

Exceeding Shelf Life: When Time Works Against Quality

Every coating material or ink has a defined shelf life during which the manufacturer guarantees the stability of its properties. Exceeding this period, however, is not just a formal issue – it can lead to irreversible changes in the material's structure. For example, in water-based coatings, gradual sedimentation of pigments and fillers occurs, while in solvent-based systems, volatile components may evaporate, altering viscosity and application properties. In reactive systems, such as two-component epoxies or polyurethanes, premature polymerization may occur, rendering them unusable.

The problem often lies in inadequate inventory control. Many companies store materials on a "first come, first served" basis, which results in older batches remaining in storage longer than recommended. The solution is to implement a FIFO (First In, First Out) system and conduct regular inventory checks with an emphasis on expiration dates. For some materials, quality can be verified using standard test methods, such as measuring viscosity or testing adhesion, but it is always better to prevent issues by adhering to the recommended storage period.

Improper Mixing and Homogenization: How to Unnecessarily Compromise an Entire Batch

Coating materials and inks are often multi-component systems where the uniform distribution of pigments, fillers, and additives is crucial for final quality. Incorrect mixing can lead to clumping, sedimentation, or uneven distribution of functional additives, which only becomes apparent during application – for example, through poor coverage, uneven gloss, or reduced durability. In some materials, particularly those with a high solids content, inadequate mixing can even cause permanent structural damage.

The basic rule is to use suitable mixing equipment that ensures sufficient intensity and uniformity of mixing without introducing air. For viscous materials, slow-speed mixers with an appropriate blade shape are ideal, while for low-viscosity systems, faster mixing is sufficient. It is also important to observe the recommended mixing time – too short a mixing time does not lead to homogenisation, while too long a mixing time can cause excessive heating or mechanical degradation of the material. For two-component systems, it is also critical to maintain the correct ratio of components and the order of their mixing to prevent premature reaction.

Insufficient Protection Against Contamination: How a Small Impurity Can Ruin an Entire Batch

Contamination of coatings and inks is one of the most common yet most underestimated risks. A small amount of foreign matter—dust, moisture, residues of another material, or even metal particles from tools—can render an entire batch unusable. In water-based systems, contamination can cause microbial growth, leading to unpleasant odours, changes in pH, or even degradation of the binder. In solvent-based systems, unwanted chemical reactions may occur, altering colour, viscosity, or application properties.

Preventing contamination begins with the handling of materials. Containers and tools should be clean, dry, and used exclusively for a specific type of material. When transferring, it is advisable to use filters or sieves to capture mechanical impurities. Storage areas should be kept clean, with minimal dust and without the presence of other chemicals that could react with coatings. For sensitive materials, such as UV inks or two-component systems, it is also important to protect them from light or moisture using appropriate packaging and storage conditions.

How to Ensure Stability and Safety of Your Raw Materials?

Every coating or ink requires an individual approach – from storage conditions to proper handling. GCG Group provides detailed technical and safety data sheets with specific recommendations for each supplied raw material and is ready to advise on optimizing processes in your operations. Contact us – or browse our catalog of over 1,300 products right away.