Common problems with putty powder
Release Time:
2020-12-16
Source:
Common problems with putty powder:
1.1 Fast drying. This is primarily related to the increased dosage of hydrated lime powder (if the dosage is too high, the amount of hydrated lime in the putty formulation can be appropriately reduced) and the water-retention capacity of the fibers, as well as the dryness of the wall substrate.
1.2 Peeling and curling. This is related to water retention; low cellulose viscosity can easily lead to this issue, or it may occur when the dosage is insufficient.
1.3 Powder shedding from interior wall putty. This is related to the dosage of hydrated lime powder (either the amount of hydrated lime in the putty formulation is too low, or the purity of the hydrated lime is insufficient; the dosage of hydrated lime in the putty formulation should be appropriately increased), as well as to the dosage and quality of cellulose, which is reflected in the product’s water-retention rate. A low water-retention rate indicates that the hydrated lime—specifically, the calcium oxide within it—has not fully converted to calcium hydroxide through hydration due to insufficient curing time, thereby causing the issue.
1.4 Bubbling. This is related to the moisture content and flatness of the wall, as well as to the construction process.
1.5 Pinholes appear. This is related to the cellulose: its film-forming properties are poor, and at the same time, impurities in the cellulose react slightly with hydrated lime. If the reaction is vigorous, the putty powder will take on a crumbly, tofu-like consistency, rendering it unsuitable for application to walls and completely lacking adhesion. Additionally, this phenomenon can also occur when carboxymethyl derivatives or similar products are added to the cellulose.
1.6 Volcanic pores and pinholes appear. This is clearly related to the surface tension of hydroxypropyl methylcellulose aqueous solutions; in contrast, the surface tension of hydroxyethyl aqueous solutions is not as pronounced. Performing a light-curing treatment will improve the situation.
1.7 Putty is prone to cracking and yellowing after drying. This is largely due to the excessive addition of hydrated lime powder: when too much is used, the putty hardens significantly upon drying, but without sufficient flexibility, it becomes brittle and easily cracks—especially under external stress. It is also related to the high calcium oxide content in the hydrated lime powder, as previously discussed.
