How faulty application can lead to bubbles and pinholes

In this article I will look at improper application techniques that may lead to bubbles appearing on the surface of a self-levelling screed. Problems during installation can be attributed to a number of reasons:

When mixing the components that make up the screed (resin, hardener, fillers) it’s important to mix at a low revolution. Mixing at high speeds may lead to the material foaming and thus an excessive amount of bubbles emerging. It is advisable to use a mixer with adjustable revolution speed and never exceed 300 rpm. Some installation teams in their hurry to finish quickly, prefer to mix for a short period of time at high speeds. Also after mixing the screed, let the new screed “rest” for 2-3 minutes before applying it.

Most importantly however is what happens when the actual epoxy screed is applied. The use of a spiked roller is essential to properly level and release any trapped air within the screed. This is a process that must be done repetitively. Furthermore the person applying the spiked roller must use spiked shoes to be able to access the entire surface. Many projects fail because the application team did not properly inspect the entire area.

Another issue with installation problems is poor lighting, a common problem when working in underground areas, and/or in facilities that are under construction and proper lighting has not yet been installed. If this is the case, then the installation team must bring its own lighting equipment so that it can properly inspect the entire surface for bubbles as well as other potential problems.

The most sensitive areas for bubble formation are near walls, corners and doors. This is because that these areas are usually not applied with a roller as much as the other areas. Furthermore visibility is somewhat limited because of possible shadows and obstructions. Ensure that one person undertakes to properly apply the roller in all these sensitive areas.

Concluding, in order to avoid bubbles and other problems during installation, the installation team must adopt a strict methodology and a lot of responsibility rests on the project manager to supervise the entire procedure.

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Akis Apostolopoulos

General Manager at Ktisis
Akis has been involved in the manufacturing and application of industrial floor coatings for the past ten years. He runs learncoatings which is an online resource training professionals on the use of epoxy floors. He is also General Manager of Ktisis, a manufacturer of flooring and waterproofing coatings.

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