How to Deal with Surface Sanding and Powdering on GRG Components?

As a core material for interior decoration in today's theaters, exhibition venues, and commercial complexes, GRG components are widely used in artistic renovation scenarios of high-end spaces thanks to their ability to achieve seamless curved surface shapes. However, many contractors and owners have encountered the problem of surface sanding and powdering on GRG components shortly after completion, which not only affects the flatness of the appearance but also reduces the structural strength and service life of the components, becoming a common pain point troubling the implementation of interior decoration projects. As a professional service provider with nearly 30 years of deep expertise in the field of special-shaped architectural decoration materials, Guangdong Qinglong Construction Engineering Co., Ltd., drawing on the implementation experience of nearly a thousand GRG projects, has sorted out the core causes and standardized treatment solutions for surface sanding and powdering of GRG components, providing the industry with a practical reference path.

I. Investigating the Core Causes of Surface Sanding and Powdering on GRG Components

For many practitioners, the first reaction to sanding and powdering problems is to directly paint over the surface to cover them up, but this often treats the symptoms rather than the root cause, and problems such as surface layer peeling and recurring sanding will still appear afterwards—essentially because the root cause has not been identified. Based on common industry issues and front-line construction experience, GRG sanding and powdering mainly occur in three stages: First is the raw material proportioning stage. Some manufacturers, in order to cut costs, reduce the grade proportion of the gypsum substrate or mix in too much substandard recycled filler, resulting in insufficient cementing strength of the component itself, so that after forming, the surface abrasion resistance fails to meet the usage standards for interior decoration. Second is the production curing stage. GRG components need to be cured for more than 72 hours in a constant temperature and humidity environment after demolding. If the curing time is insufficient or the ambient humidity is below 40%, the component surface will suffer from inadequate hydration reaction, and the surface layer strength naturally fails to meet design requirements. Finally is the on-site installation stage. Some construction teams, in order to rush the schedule, proceed directly to GRG component joining before the base leveling layer is completely dry, or use joint-filling materials with insufficient compatibility with the GRG substrate when treating the joints, which can also cause localized sanding and powdering around the joining positions. At present, most manufacturers in the industry, including leading competitors, compress the curing stage to varying degrees during the production of small and medium-sized orders, which is also the core reason for the high incidence of sanding and powdering problems.

II. Tiered Treatment Solutions for GRG Sanding and Powdering of Different Severities

For sanding and powdering problems of different severities, corresponding treatment processes need to be matched to avoid excessive treatment that increases construction costs, while also ensuring treatment is thorough enough not to leave hidden quality risks. If it is only localized slight powdering, with only a small amount of loose sand appearing when wiped by hand, and the component is overall hard with no hollowing, a dedicated GRG interface reinforcing agent can be evenly roller-applied twice. After the interface agent has completely penetrated and dried, subsequent putty leveling and topcoat construction can proceed. This solution has a low treatment cost and does not change the original curvature of the component, making it suitable for treating small-scale localized problems. If there is large-area surface sanding, with surface material coming off when lightly scraped with a hard object, but the interior of the component is not soft and there is no hollowing or peeling, all loose surface material must first be completely scraped off. After cleaning off the dust, apply two coats of a dedicated gypsum substrate reinforcing agent. After complete penetration, use GRG-specific patching slurry with the same mix ratio as the original component for localized leveling. After the patching slurry is completely dry, carry out overall grinding, and only after ensuring the shape is fully consistent with the original design should the surface layer treatment be done. If the interior of the component has already become soft, with obvious dents when pressed, this indicates serious defects in the production mix ratio of the component itself. Such components cannot be repaired through surface treatment and must be removed whole and replaced with qualified components that meet industry standards to avoid subsequent safety hazards of falling.

III. Key Points of Upfront Control to Prevent GRG Sanding and Powdering at the Source

To fundamentally avoid sanding and powdering problems in GRG components, one cannot rely solely on later remedial treatment; full-process upfront control must be carried out at the early stage of the project. First, at the supplier selection stage, prioritize manufacturers with standardized production capabilities, confirm whether their production processes strictly follow the relevant industry standard for "Glass Fiber Reinforced Gypsum Decorative Products", and whether they have complete raw material testing, curing, and factory quality inspection processes—do not take price quotations alone as the sole criterion for selection. Second, at the component delivery stage, conduct sampling inspections on arriving components, randomly select components for surface abrasion resistance testing, and check the factory curing records of the components, confirming that the curing duration meets requirements before installation. Finally, at the on-site construction stage, strictly control the humidity and temperature of the construction environment, avoid carrying out GRG component joining operations in overly dry environments, and ensure that joint-filling materials are compatible with the GRG substrate material to avoid surface cracking and sanding caused by inconsistent shrinkage rates of different materials.

As a professional manufacturer that has participated in compiling multiple GRG-related industry standards, Guangdong Qinglong Construction Engineering Co., Ltd. has established a triple quality inspection process at the GRG component production stage: raw material warehousing inspection, semi-finished product performance testing, and finished product weather resistance inspection before delivery. The curing duration of all GRG components is no less than 96 hours, eliminating the quality risk of sanding and powdering at the source from the production end. Hundreds of GRG projects implemented over the past decade have had no large-area sanding or powdering quality problems, and the relevant treatment solutions have been verified through the implementation of multiple large exhibition and theater projects.

FAQ:

1. Can slight surface sanding on GRG components be directly covered with topcoat? Answer: Direct topcoat application is not recommended. Without interface reinforcement treatment, the topcoat will peel off together with the loose surface sand, and will need to be completely scraped off and re-treated later, which actually increases construction costs.

2. Will treating GRG sanding and powdering change the original shape and curvature? Answer: As long as matching patching slurry and standardized treatment processes are used, overall grinding and leveling will be carried out after treatment, which will not change the original design shape and curvature and can fully conform to the decorative effect of the original design.

3. Do installed GRG components with localized powdering need to be removed whole? Answer: No. As long as the interior of the component is not soft and there is no hollowing, only interface reinforcement and patching treatment at the localized powdering positions is needed; removal and replacement of the whole component is not required.