What Causes Color Differences in Paint?
2 Answers
It may be due to the influence of humidity and temperature. Below is the expanded content: Impact of Humidity and Temperature: The temperature and humidity of the spraying environment significantly affect the color difference of the topcoat. This is because environmental temperature and humidity influence the evaporation rate of paint solvents. Higher temperatures cause solvents to evaporate faster, while lower temperatures slow down evaporation, thereby affecting the surface drying time of the paint film. Similarly, high humidity slows solvent evaporation, while low humidity speeds it up, also impacting the surface drying time of the paint film and leading to color differences. Impact of Baking Temperature: Different baking temperatures have a certain effect on the color difference of the paint film. The baking process is a physical-chemical transformation from quantitative to qualitative changes. The baking temperature and duration greatly influence this process. Lower temperatures slow down the cross-linking reaction, and if the temperature falls below the specified range, the paint film may not fully dry, affecting its performance. Higher baking temperatures accelerate the cross-linking reaction, but if the paint film forms too quickly, it can compromise leveling, resulting in a rough surface. Excessive baking temperatures beyond the specified range can cause over-baking, leading to yellowing of the paint film and color differences. Impact of Air Pressure: Variations in compressed air pressure greatly affect the color difference of the paint film. This is because air pressure determines the size of atomized paint particles. Lower compressed air pressure results in poor atomization, producing larger paint particles that form a rough and dull paint film on the surface. Higher air pressure generates finer paint particles, but excessive pressure causes overspray, not only reducing paint film quality but also affecting the paint transfer efficiency and contributing to color differences.
Last time my car got scratched and I went for a paint touch-up, but after it was done, I noticed the color didn't match the original. I asked several technicians before figuring it out. It turns out the most common cause of paint color mismatch is inaccurate color mixing. Incorrect paint mixing ratios or lack of experience from the paint mixer can both lead to color deviations. Additionally, the condition of old and new paint differs—original car paint ages and changes color due to weathering, while newly applied paint looks more vibrant, making the difference obvious when placed side by side. The painting environment is also crucial; high humidity can affect the drying speed of the paint, resulting in uneven color shades. Moreover, differences in raw materials between paint batches mean that even with the same formula, touch-up paint may still show color variations. So, I recommend having the technician carefully compare the color card under natural light before painting to minimize the color difference as much as possible.
