How can the problem of putty powder flaking be solved?
Release Time:
2015-10-16
Source:
How can the problem of putty powder flaking be solved?
For users of putty powder, Putty powder Powdering is a very serious problem; it can cause latex paint to peel off and lead to blistering and cracking in the putty layer, which in turn results in cracking of the latex paint finish. So what causes powdering in interior and exterior wall putty? The reasons include both material-related factors and construction-related factors. , and is also caused by various factors such as unreasonable formulation design.
1. Insufficient bonding strength of putty leads to powdering; manufacturers, in their relentless pursuit of cost reduction, often use low-quality binder powders with poor bonding performance and add them in insufficient quantities. This is particularly true for interior wall putties, where the bonding strength—and whether or not powdering occurs—are heavily influenced by the quality and dosage of both the binder powder and the adhesive.
2. Unreasonable formulation design, material selection issues, and structural problems are all critical in putty formulations. For example, when hydroxypropyl methylcellulose (HPMC) is used in interior-wall putties that are not waterproof, although HPMC is quite expensive, it has no effective binding or stabilizing effect on fillers such as double-fly ash, talc, and wollastonite. If HPMC is used alone, it will lead to Powder shedding occurs, whereas low-priced CMC and CMS do not exhibit powder shedding; however, CMC and CMS are unsuitable for waterproof putty or exterior-wall putty because they react with lime powder and white cement, both of which can trigger powder shedding. Similarly, adding polyacrylamide to lime powder or white cement to formulate a waterproof coating will also result in chemical reactions that cause powder shedding.
3. Uneven mixing is the primary cause of powder shedding in both interior and exterior wall putties. Many manufacturers across the country use simple, makeshift equipment for producing putty powder—ranging from rudimentary to highly varied—and none of it is dedicated mixing machinery. This results in uneven mixing, which in turn leads to powder shedding. The patented horizontal multi-screw ribbon mixer developed by Henan Huikang Industrial Corporation effectively addresses this issue. This issue, and the price is not high.
4. Production-process errors can cause putty to chalk or flake. If the mixing equipment lacks a cleaning function, significant residue will remain, leading to reactions: in standard putties, CMC will react with the hydrated lime powder in waterproof putties; in interior-wall putties, CMC and CMS will react with the white cement in exterior-wall putties, resulting in chalking. Specialized equipment from Henan Huikang Company. A cleaning port is provided to thoroughly remove residual material from the machine, ensuring consistent putty quality while enabling multi-purpose operation—allowing a single unit to produce multiple types of putty.
5. Differences in the quality of fillers can also easily lead to powder shedding. Both interior and exterior wall putties make extensive use of fillers; however, the calcium carbonate content and pH levels vary among different grades of heavy calcium carbonate powder and talc powder, which can in turn cause powder shedding in the putty. For example, when using the same cellulose ether binder, interior wall putty powders from Chongqing and Chengdu—though formulated with identical types of filler—differ in their talc and heavy calcium carbonate compositions. It varies: in Chongqing, fans don’t unfollow; in Chengdu, they do; in Henan and Northeast China, they don’t; but in some other regions, they do.
6. Weather conditions are also a contributing factor to powdering of interior and exterior wall putties. For example, in some arid regions of northern China where the climate is dry and ventilation is good, the putty film forms quickly and does not powder; however, this is not the case in the south, particularly in areas with prolonged rainy seasons. The persistent humidity in these regions impairs the film-forming properties of the putty, which can also lead to powdering. To prevent powdering, waterproof putty containing hydrated lime powder is used in such areas.
7. Inorganic binders such as lime powder and white cement are impure and contain large amounts of double-fly ash. The so-called multi-functional lime powder and multi-functional white cement available on the market are likewise impure; because these impure inorganic binders are used extensively, waterproof putties for both interior and exterior walls will inevitably chalk and fail to provide effective waterproofing.
8. In summer, exterior wall putty often lacks sufficient water retention; particularly in high-temperature, well-ventilated areas such as the entrances and windows of high-rise buildings, the lime powder and cement may lose moisture before their initial setting time is complete, and inadequate curing can further lead to severe powdering.
