After adding paint hardener, some areas are not dry. How to troubleshoot and solve the process problems?
Release Time : 2025-09-16
Spots of paint hardening after adding paint hardener are often related to the paint hardener mix, mixing process, application environment, or material compatibility, requiring a systematic investigation to identify the root cause. First, check whether the paint hardener to base ratio meets the manufacturer's specifications. Excessive or insufficient paint hardener can lead to incomplete reaction, especially in two-component paints. If the paint hardener is added below the standard ratio, the chemical crosslinking reaction won't proceed adequately, potentially causing spot hardening. Before application, strictly follow the product instructions for weighing and measuring, avoiding empirical estimates. Also, confirm that the paint hardener used is the correct model. Different brands or models of paint hardener may be incompatible with the base, leading to abnormal reactions.
Insufficient mixing is another common cause. Failure to use a dedicated agitator or insufficient mixing time when mixing the paint hardener and base can result in uneven distribution of the paint hardener, creating "unreacted areas." For example, manual mixing can easily create dead spots, while an electric agitator requires running at a constant speed for 10-15 minutes to ensure complete incorporation. Furthermore, applying the mixture directly without allowing it to rest and cure can result in insufficient paint hardener concentration in some areas due to incomplete air bubbles. It's recommended to allow the mixture to rest for 5-10 minutes after stirring, allowing bubbles to dissipate before applying.
Application conditions significantly influence curing results. Low temperatures inhibit chemical reaction rates. If the ambient temperature falls below the paint's minimum drying temperature, even if the paint hardener is correctly proportioned, it may not dry for a long time or may partially stagnate. Excessive humidity can slow solvent evaporation, hindering contact between the paint hardener and the base. This is especially true in humid weather or in confined spaces with poor ventilation, where water vapor condenses on the paint film, forming a barrier layer. In these cases, use a heating device to raise the ambient temperature to 20-30°C and increase ventilation to reduce humidity. If necessary, add slow-drying water to extend the operating time, but avoid excessive use, which may delay drying.
Material compatibility and storage conditions should also be checked. If the paint hardener or base is expired, their active ingredients may degrade and become ineffective, resulting in incomplete reaction. Check the seal of the packaging drum to ensure there are no leaks or moisture. Store away from high temperatures, direct sunlight, and corrosive substances. Improper substrate preparation can also indirectly cause problems. For example, excessive moisture content in wood, incomplete rust removal on metal surfaces, or inadequate sanding of old coatings can hinder the adhesion of the paint film to the substrate, leading to localized curing problems. Before application, ensure the substrate is dry, clean, and meets the paint's substrate pre-treatment requirements.
Careful attention should also be paid to the selection and use of thinners. Unsuitable thinners can disrupt the balance between the paint hardener and the base. For example, thinners containing alcohol or high water content can dilute the paint hardener concentration and slow the reaction. Use only the manufacturer's specified thinner and control the amount added to avoid over-thinning, which can result in a thin film or uneven distribution of the paint hardener. If viscosity adjustment is necessary, it is recommended to add small amounts in batches, stirring thoroughly, and then testing for drying.
If areas remain dry after application, remedial measures should be taken depending on the severity of the problem. For minor areas of staining, try sanding until they are completely dry, clean the surface dust, and reapply. For larger or deeper stains, completely remove the existing paint film, ensure the substrate is dry and free of contaminants, then re-adjust the paint and apply. For high-value or complex workpieces, it is recommended to contact a professional technician for an on-site assessment to avoid further damage due to improper handling.
The key to preventing these issues lies in standardized construction processes and detailed control. From material acceptance, proportioning, mixing, to environmental control, every step must strictly adhere to operating procedures. Furthermore, enhanced training should be provided to improve the ability of construction personnel to identify and address anomalies. By maintaining construction records and tracking the use and environmental parameters of each batch of materials, a basis for subsequent issue analysis can be provided, continuously optimizing process stability.