I. For Paint Manufacturers: Hidden dangers at the production end are often the most deadly.
Paint manufacturers are the source of the whole industrial chain. If there is something wrong with the source, there will be problems with all the color matching and mixing in the back. Therefore, manufacturers must follow the correct coating standard operating procedures when mixing coatings in order to avoid errors.
1. The base paint is incompatible with the color paste.
With the increasingly stringent global environmental regulations, especially the increasing restrictions on VOCs (volatile organic compounds), most color paste formulations have undergone fundamental changes. The content of organic solvents, which were commonly used in the past, has been significantly reduced, and water-based systems are gradually becoming the mainstream. However, the compatibility of water-based systems is not as good as that of solvent-based systems. Some adjusted formulations may not necessarily be perfectly compatible with all types of paint dispenser machines and base paints.
Compatibility issues with color pastes primarily manifest as pigment flocculation, coarsening, or precipitation from the coating. These phenomena directly result in reduced tinting strength of the color paste, necessitating an increase in the amount used to achieve the desired color. This not only increases costs but also leads to uneven distribution of the color paste within the coating, severely compromising the cost-effectiveness and reproducibility of color matching.
Coating standard operating procedures: Before batch production, it is essential to conduct small-scale compatibility tests between new batches of color paste and existing base coats. Do not rely solely on hearsay or manufacturers’ unilateral recommendations; practical testing is the only reliable method. Practice is the sole criterion for testing truth. Only once compatibility has been confirmed should formal production commence.
2. Unstable Viscosity of Color Paste in the Drum
The viscosity stability of the color paste is directly linked to the normal operation of the paint dispenser machine. If the viscosity of the color paste is too high or unstable, the outlet of the color paste tank is prone to blockage. Once blocked, the consequences range from color paste wastage in mild cases to the need to replace an entire set of components or even the entire machine—the subsequent maintenance costs of which are often far greater than anticipated.
3. Overlooked Equipment Defects
A leaking discharge valve is a seemingly minor issue with serious consequences. Impurities can form at the nozzle of the discharge valve; these impurities contaminate the color paste, thereby severely affecting the final mixing result. Many manufacturers have become accustomed to the “fix it when it breaks” approach, which is incorrect. The prudent course of action is to carry out regular preventive maintenance and inspections on machines such as mixers, shakers, and paint dispenser machines. A machine in good working order is a prerequisite for ensuring color consistency and coating standard operating procedures.
4. The Problem of Air Bubbles in Color Pastes
Whilst surfactants reduce the surface tension of liquids, they inevitably generate air bubbles during the dispersion process. Excessive air bubbles not only prolong production time but, more importantly, when color paste containing air bubbles is added drop by drop, the actual amount of color paste added in each drop will vary. This cumulative error is sufficient to cause the color of an entire batch to deviate from the target value.
5. Underestimation of Storage Contamination
Storage is another very important step in the coating standard operating procedures. Although storage conditions may appear to have no direct relation to “mixing”, they actually have a profound impact. Adverse storage environments and improper handling can lead to bacterial growth and compromise the integrity of the paint film inside the tanks. Deteriorated color paste is not only unusable but may also pose a health hazard to operators due to the unpleasant odours it emits. Maintaining a clean storage area with appropriate temperature and humidity levels is a fundamental requirement for every paint manufacturer.
II. For Manufacturers Using Paint Dispenser Machines: The Details of Day-to-Day Operations Determine Success or Failure
A paint dispenser machine is a crucial link between the factory and the consumer. Every operational detail here has a direct impact on the finished product.
Improper Addition of Color Paste
The color paste must be shaken well before each addition – this rule sounds simple, yet it is the one most easily overlooked. This is particularly true for inorganic color pastes, which are prone to settling; if the shaking step is omitted, the resulting uneven concentration caused by sedimentation will mean that the actual amount of color paste added varies with each addition.
Another detail that is easily overlooked is the timing of the addition. The coating standard operating procedures is to add color paste at the end of the working day. Why add new color paste at the end of the day? Because any air introduced during the addition process will be naturally expelled from the pipework overnight via the paint dispenser machine’s recirculation and agitation systems. If the color paste is hastily added in the morning, air bubbles in the pipework may affect the machine’s color-matching accuracy throughout the day.
In practice, there is another coating standard operating procedures to bear in mind: adjust the lightness first, then fine-tune the hue. The shade determines the foundation of the color’s lightness; fine-tuning the hue on this basis is more efficient and results in fewer errors.
III. For Manufacturers Using Mixers and Shakers: The Final Line of Defence in the Mixing Process
Simply adding color paste does not guarantee the color is correct. Mixing and shaking are the final steps in ensuring the color is “uniformly distributed”; if this step is not carried out properly, all previous efforts may be in vain.
1. Incorrect Positioning of Paint Drums
Placing paint drums in the wrong position—it may sound like a mistake only a novice would make, but in reality, it is not uncommon in a busy factory environment. If the drum is not centred or is tilted, the mixer and shaker will be unable to blend the colour paste with the base paint effectively.
The correct coating standard operating procedures are to always keep the drum upright. An upright drum ensures that the forces generated by stirring or agitation are distributed evenly throughout the interior, achieving homogenisation and color uniformity more quickly.
2. Neglecting Safety Operating Procedures
In the pursuit of efficiency, safety is often the first casualty. Failing to read the instruction manual carefully before starting the machine, or neglecting to check that plugs and doors are securely fastened during the mixing process—these seemingly “time-saving” practices are, in fact, setting you up for danger.
If you notice any unusual noises, vibrations, or odours during the mixing process, press the emergency stop button immediately to halt operation. Do not take the risk of thinking, “It’ll be fine if I just let it run a little longer.”
3. The Pitfalls of “Mixing and Matching”
Another easily overlooked issue is the mixing of paints from different brands or of different types. The ingredients in color pastes from different brands may conflict; when mixed, this can lead to color instability or color differences, with a risk of color patches or fading later on. Different types of paint (such as emulsion paint, oil-based paint, acrylic paint and epoxy paint) have varying pigment solubility and film-forming properties; mixing across types can lead to separation or clumping.
The coating standard operating procedures: Only paints of the same type should be mixed together for color matching. Oil-based paints must not be mixed with water-based paints for color matching, as this will inevitably result in sedimentation. When mixing colors, use products from the same brand and series wherever possible.
IV. Coating Standard Operating Procedures: Turning These Habits into Muscle Memory
In addition to the errors discussed in the previous sections, there are some general coating standard operating procedures that apply throughout the entire coating mixing process, which every operator should bear in mind:
- Reset before starting: Before initiating the mixing programme, ensure that the emergency stop button has been released. Many machines cannot be started whilst in an emergency stop state, whilst others will display an error message if the emergency stop has not been reset—regardless of the situation, it is good practice to reset the emergency stop button before starting the machine.
- Check the positioning of the drums: Whether mixing with a single drum or multiple drums, ensure that the drums are correctly positioned, centred and upright before starting the machine.
- Select the correct settings: The shaking modes for single-drum and multi-drum mixing often differ; ensure the appropriate settings are selected before starting the machine.
- Set a suitable mixing time: A longer mixing time is not necessarily better, nor is a shorter one. An excessively short mixing time may result in the color paste not being fully dispersed, whilst an excessively long mixing time may introduce too many air bubbles or cause excessive shear, thereby affecting the performance of the coating. When operating the equipment, refer to the equipment manual and the pigment supplier’s recommendations to select the optimal mixing time.
- Close the door before starting: Before initiating the mixing programme, remember to close the equipment door and ensure it is securely locked. This is not only a safety requirement but also a prerequisite for the equipment to function properly—many mixers cannot be started if the door is not properly closed.
Conclusion
Paint mixing may appear to be a very simple operation—add the pigment, shake it up, and dispatch the product. However, in reality, from the selection, storage, and addition of color pastes, through to equipment maintenance and operation, and the setting of mixing parameters, there are numerous details to consider at every stage. Every step must follow coating standard operating procedures.
Color performance is a key focus in the paint and coatings industry. The physical and chemical properties of a formulation—viscosity, hardness, density, and gloss—all depend on the type and concentration of the pigments. Achieving the perfect color also depends on the quality of the machinery, the standard of maintenance, and the professional expertise of each operator.
One fewer mistake means one fewer complaint about color discrepancies; one more instance of standard operating procedure means one more point of customer trust.
If you would like to learn more about coating standard operating procedures for paint dispenser machines, mixers, and shakers, please feel free to contact us at any time. We are available 24 hours a day.
