Wall Putty & Skim Coat

Skim coating, also named Wall putty, is refined techniques in modern construction, widely used on both interior and exterior facades, ceilings, and walls to achieve smooth, uniform surfaces. By applying multiple ultra-thin layers of a mortar mixture, these methods effectively fill even the smallest imperfections in the substrate, resulting in a virtually seamless, flat finish.

A properly skim-coated and puttied surface must exhibit excellent paint-film adhesion to prevent peeling, as well as superior resistance to chalking, so that it maintains structural integrity and a pristine appearance even under harsh environmental conditions.

Skim coat

RDP

Recommend： 4010, 5020, 9208H

HPMC/HEMC

Recommend： HPMC 7706

Starch ether

Recommend: 3K

Cellulose fiber

Recommend： WF200, WF500, WF600

Water repellent

Recommend： WR 680, H600, H7086

Polyvinyl alcohol

Recommend： PVA 1788

RDP

Recommend：

HPMC/HEMC

Recommend：

Starch ether

Recommend:

Cellulose fiber

Recommend：

Water repellent

Recommend：

Polyvinyl alcohol

Recommend：

Testing

Flexibility test

As walls and masonry structures are subjected to both compressive forces and tensile stresses, the skim coat’s compressive and flexural strengths are evaluated in accordance with EN 1015-11 to better understand the structural performance of the wall system.

Tensile adhesive

In this test, a polymer-enhanced skim coat is applied onto a thin sheet. The panel is then bent over cylinders with different diameters to evaluate the material’s flexibility and its ability to resist cracking under dimensional deformation.

Open time

Condition the sample in an oven, then evaluate workability. Putty workability after heat exposure: oven 50 °C, 2 h 20 min → workability test.

Workability

Properties such as workability are strongly influenced by both the methyl cellulose, RDP and other additives. On-site evaluation provides an effective assessment of key attributes: a firm, dense feel during application is a reliable indicator of optimal consistency, good water retention, and strong cohesiveness.

Compressive strength test

The tensile adhesion test evaluates how effectively a skim coat bonds to its base material. In this procedure, the skim coat is placed onto a surface and allowed to cure under standardized conditions, including thermal exposure. The bonding performance is then measured after 14 and 28 days.

Paint adhesive

The cross-hatch adhesion test is used to assess how well emulsion paint bonds to a skim coat surface. In this method, paint is first applied to the skim-coated substrate and conditioned under standard settings. After a 7-day period, a grid pattern is cut into the surface, which is then covered with masking tape.