Views: 0 Author: Site Editor Publish Time: 2025-11-24 Origin: Site
CMC is a key product of Shijiazhuang Cellulose Co., Ltd. This building-grade chemical additive ensures excellent construction results. CMC powder is widely used and appreciated globally.
Comparison Dimensions | Neutral putty (non-alkaline putty) | Alkaline putty (gray calcium-based/cement-based) |
| Core cementing materials | Plaster or organic adhesive | lime powder or cement |
| pH value | Neutral or slightly alkaline (pH 7-9) | Strongly alkaline (pH 12-14) |
| Main features | 1. Stable properties, does not readily react with substances 2. Minimal skin irritation 3. Does not affect paint color 4. Moderate moisture resistance (gypsum-based) | 1. High hardness and strong water resistance 2. Has antibacterial and antifungal properties 3. May cause paint discoloration and yellowing. |
| advantage | 1. Safe and environmentally friendly, easy to apply. 2. Excellent paint compatibility, especially for light and colored paints. 3. Low shrinkage rate, not prone to cracking. 4. Not easy to burn your hands after application. | 1. High strength, water and scrub resistant 2. Excellent mildew and algae resistance 3. Relatively low cost (gray calcium based) 4. Fast drying speed |
| shortcoming | 1. Less moisture-resistant than alkaline putty (gypsum-based) 2. Usually more expensive 3. May be slightly less hard than high-quality alkaline putty | 1. Strong alkalinity can burn some pigments, causing discoloration of the paint surface. 2. It can irritate the skin of those applying the paint. 3. It has relatively high shrinkage, posing a risk of cracking. 4. It requires precise application and thorough drying. |
| Applicable Scenarios | 1. All dry indoor areas 2. Situations where it must be used: - Painting light-colored or brightly colored latex paint - Applying metallic or silk wallpaper - Using sensitive finishes such as artistic paint or diatomaceous earth | 1. High humidity environments: kitchens, bathrooms (water-resistant type required) 2. Areas with high mold resistance requirements: basements 3. Exterior wall putty (must be cement-based water-resistant putty) 4. As a base coat for non-light-colored paints |
| Construction Precautions | 1. Ensure the substrate is firm and free of dust. 2. Add water according to the instructions, avoiding over-diluting. | 1. Ensure the paint is completely dry (usually requiring 3-7 days of curing) before applying it; otherwise, alkaline substances and moisture will leach out, damaging the paint film. 2. Wear gloves and safety goggles during application. 3. Before painting, it is recommended to apply a high-quality alkali-resistant primer for sealing and isolation. |
In-depth Analysis
1. Understanding its Essence from its Composition
Alkaline Putty:
Hydroxy-based Putty: The main binder is hydrated lime powder (calcium hydroxide). Calcium hydroxide is strongly alkaline when it comes into contact with water and reacts with carbon dioxide in the air to form calcium carbonate (the main component of limestone), thus hardening. This process releases heat and moisture.
Cement-based Putty: The main binder is cement. Cement produces a large amount of calcium hydroxide after hydration, therefore it is also strongly alkaline.
It is the presence of this calcium hydroxide that gives the putty its alkalinity.
Neutral Putty:
Gypsum-based Putty: The main binder is gypsum (calcium sulfate). Gypsum itself is neutral or weakly alkaline and chemically very stable.
Organic Adhesive Putty: Uses polymers (such as CMC, pregelatinized starch, etc.) as the main binder, and its pH value is also controlled to be close to neutral.
They contain little or no active calcium hydroxide, therefore their pH value is stable within the neutral range.
2. Core Contradiction: Alkalinity vs. Paint Stability
This is the most crucial difference between the two, directly determining the final decoration effect.
The "Staining" Problem of Alkaline Putty: Latex paint, especially some organic pigments and certain formulations, is very sensitive to alkaline environments.
If alkaline putty is not completely dry or not effectively sealed with an alkali-resistant primer, the alkaline substances inside will migrate to the paint film along with moisture.
This highly alkaline environment will damage the chemical structure of the pigments, leading to yellowing, discoloration, and uneven coloring of the paint surface, especially noticeable on light-colored paints (such as white, light pink, and light blue).
This is the fundamental reason why construction specifications emphasize "applying alkali-resistant primer only after the putty is completely dry."
The "Safety Guarantee" of Neutral Putty: Due to its stable chemical properties, it will not react harmfully with any components of latex paint.
Regardless of whether the putty is completely dry, there is no risk of "staining." This greatly reduces the difficulty of construction and the requirements for the craftsman's experience, providing an "insurance" for the final paint surface effect.
