How to use hydroxypropyl methylcellulose correctly to apply putty powder

Hydroxypropyl methylcellulose (HPMC) is an additive widely used in the construction industry, especially for the preparation of putty powder. The correct use of HPMC can improve the construction performance and quality of putty powder. The following will introduce in detail the role and use of HPMC in putty powder.

1. Characteristics and functions of hydroxypropyl methylcellulose

Water retention: HPMC has good water retention capacity, which can keep the putty powder moist during the drying process and avoid cracking or falling off caused by too fast drying.

Thickening effect: As a thickener, HPMC can increase the viscosity of putty powder, increase its construction fluidity, and make it easier to apply and shape.

Improve adhesion: HPMC can enhance the adhesion of putty powder to the substrate and make the coating more firm.

Convenient construction: HPMC can make putty powder have good construction properties, such as easy scraping and good lubricity.

2. Adding method of HPMC in putty powder

Premixing method: Evenly mix HPMC with other dry powder materials (such as gypsum, white cement, heavy calcium, etc.). This method is simple and quick, and can ensure the uniform distribution of HPMC in the dry mix.

Dissolving method: First dissolve HPMC in water, wait for it to completely swell to form a colloidal liquid, and then mix it with other putty powder materials. This method can better exert the water retention and thickening effect of HPMC, but the operation is relatively complicated.

Specific steps:

Dry mixing method: Add HPMC to the putty powder mixture in proportion, usually 2-5 kg of HPMC per ton of putty powder. Use a stirring device to mix it thoroughly to ensure that HPMC is evenly distributed.

Wet mixing method: Slowly add HPMC to clean water (warm water is better), and stir continuously until a uniform colloidal solution is formed. Then add it to the putty powder and continue to stir evenly.

3. Precautions

Adding ratio: The amount of HPMC added should be adjusted according to the specific formula and requirements of the putty powder. Usually, the amount of HPMC added is 0.3%-0.5% of the total weight of putty powder.

Mixing time: When using the dry mixing method, the mixing time should be sufficient to ensure uniform mixing of HPMC and other materials. In the wet mixing method, the time for HPMC to completely dissolve should be at least 30 minutes to avoid incomplete swelling of the particles.

Temperature control: HPMC has certain requirements for temperature when dissolving, and cold water or warm water (below 40°C) should usually be used. High temperature may cause uneven dissolution of HPMC or form lumps.

Environmental conditions: At the construction site, avoid direct sunlight and high temperature environment. Excessive temperature will affect the performance of HPMC and the construction effect of putty powder.

Storage conditions: HPMC should be stored in a dry and ventilated environment to avoid moisture and lumps. HPMC that has not been used up after opening should be sealed and stored.

4. Quality control

Raw material testing: Before using HPMC, the raw material quality should be tested to ensure that its viscosity, fineness, water content and other indicators meet the requirements.

Construction test: Prepare a small sample of putty powder for construction test, observe its construction performance, water retention, fluidity, etc., to ensure that the addition amount and mixing method of HPMC are appropriate.

Terminal inspection: After the construction is completed, the putty powder layer should be terminally inspected, including flatness, adhesion, drying time, etc., to ensure the construction quality.

5. Construction suggestions

Surface treatment: Before applying putty powder, the surface should be clean and dry, free of dust, oil and other loose materials to ensure the bonding effect of putty powder.

Construction steps: After the putty powder is prepared, it should be used as soon as possible to avoid long-term storage affecting the performance. When applying, the layered construction method is adopted, and the thickness of each layer should be controlled between 1-2 mm to avoid cracking caused by excessive thickness of a single layer.

Maintenance treatment: After the application is completed, proper maintenance should be carried out to avoid exposure in an overly dry or humid environment to ensure the hardening and adhesion of the putty powder layer.

Hydroxypropyl methylcellulose plays an important role in putty powder. Its water retention, thickening and construction performance improvement properties make it an important additive for putty powder. During use, it is necessary to select the appropriate addition method and proportion according to the formula and construction requirements of the putty powder, and pay attention to environmental conditions and construction steps to ensure the final quality and construction effect of the putty powder. Through the reasonable application of HPMC, the performance of putty powder can be significantly improved, ensuring the lasting beauty and durability of architectural decoration.