6 Worst Problems and Solutions of Interior Wall Putty in Painting Projects

Interior and external wall putty is an indispensable auxiliary material in painting projects. With the development of the architectural coating industry, the use for exterior and interior wall putty has become extensive. Many coating projects have encountered various quality problems such as difficulty scraping putty, blistering, cracking the surface layer, and peeling off. MIKEM is a particular HPMC supplier for  exterior and interior wall putty.

We combined with years of research and development experience and customer feedback analysis. This article deeply analyzes the problems and solutions to provide relevant industry players with practical construction experience.

1. The base surface construction that is too dry or too wet will cause chalking

Most of the interior wall putty is air-hardening materials with Ca(OH)₂ as the primary cementing material. It requires high humidity on the base surface of the wall and the construction environment. When the moisture is within 25%~75%, calcium hydroxide can react well with CO₂ and H₂O in the air to form CaC0₃ crystals with a compact structure.

When the humidity is too high, the CO₂ in the air is correspondingly low. And when the humidity is too low, the HO is insufficient. As a result, the CaCO₃ crystal structure formed by the reaction is loose, and the strength of the putty will be very low or even not hardened.

To solve this problem, it is necessary to construct in a suitable construction environment, or to spray water on a wall that is too dry. It is also necessary to prevent construction on a wall that is too wet. If the wall cannot be dried for a long time, it is recommended to use cement-based exterior wall putty (hydraulic putty) for construction.

2. If the slurry is left open for a long time, the surface will crust

Because the surface of the slurry is exposed to air for a long time, the Ca(oH)₂ on the surface of the interior wall putty slurry can be combined with the CO in the air. The reaction generates CaC0 and crystallizes. Simultaneously, the colloidal components in the interior wall putty will lose water to form a film. It will further form a crust on the surface, and the putty will fail. For air-hardening materials, isolation of air can prevent them from hardening. If you want to use the mixed putty the next day, the slurry can be sealed and insulated from the air for storage. As long as the water does not escape or lose, it can maintain good workability.

3. Repeated water spray on the interior wall putty will cause chalking and peeling

The interior wall putty is hardened. Repeated water is drenching, and repeated wet and dry cycles. then the CaC0₃ crystals will gradually transform into soluble Ca(HCO₃)₂ and dissolve. In addition, the re-dispersible latex powder used for interior wall putty is often non-water-resistant latex powder. It will causes powdering of the putty layer.

Cement-based exterior wall putty can be used for repeated water spraying, but water spraying will increase cement-based putty’s strength.

4. For wood plank surface, peeling will occur during construction

Interior wall putty is directly scraped on the surface of the wood board due to insufficient adhesion and insufficient toughness and cannot resist the swelling and shrinking deformation of the wood layer or slight vibration. The phenomenon of shelling and falling off will occur.

When scraping putty on the wood board, an additional 5% of white latex should be added to increase the adhesion and toughness. Simultaneously, the wood board should be varnished first to avoid yellowing in the later stage. Or choose an R-type exterior wall putty (dynamic crack resistance greater than 0.3m).

5. Complicated skin and severe chalking will occur during long-term wet base construction

The lime-based putty batch is on the damp base surface. The outer layer of the putty can crystallize and harden well. Still, the base surface’s inner side will lose the crystals due to long-term humidity. It will cause the skin to be hard and the inside is not hard. Pieces of the skin will be peeled off during polishing, and the polished surface will be severely chalked.

The construction must be carried out after the wall surface is dry. Because, in this way, the ideal reaction environment required for the calcification of lime-based putty can be obtained. If necessary to construct such a base surface, the cement-based putty should be selected as the construction material.

6. The problem of small bubbles will occur in the construction of the damp base surface

Some walls seem to be dry on the surface, but the interior moisture is heavy. Especially in a division that has just finished pouring concrete or a wall that has just finished cement mortar, the surface often looks very dry in sunny or dry weather, but there is a lot of water inside the wall. When the interior humidity of the wall is greater than the exterior air humidity of the wall, there will be an air pressure difference, and the moisture will diffuse to the outside of the wall. If the interior wall putty is applied to the wall at this time, dense small bubbles will appear immediately.

It is necessary to choose a suitable construction time and wait for the moisture inside the wall to evaporate before proceeding with putty construction. If the construction period is tight, you can also perform thin batching and compaction for the first time on the damp wall to block the steam holes on the wall. And then scrape the second time immediately before the first time seems to be dry, which can significantly reduce the number of small bubbles.

Except for suitable construction,interior wall putty quality is also of great importance for avoiding common problems. Our MelaColl™ cellulose ether and Mikrant™ products are extensively used in interior wall putty application. They exhibit the following properties in construction:

Thickening: our products can thicken putty powder to enhance its suspension ability, anti-sagging ability as well as keep the solution uniform.

Water retention: Our products can keep the putty powder in a moist state and make the auxiliary ash calcium react under the action of water.

Lubrication: our product has a lubricating effect. That can make the putty powder have good workability, keep it smooth, and human-energy saving during the construction process.

The above is about the problems and solutions of interior wall putty. We will discuss the issues and solutions in the construction of exterior wall putty in the next article. For more related knowledge, stay tuned to MelaColl™!