Guangdong Crown Paint Company Limited

What causes the orange-peel effect in epoxy floor coatings

 Take a look at the picture of the floor surface above. Notice the texture: Instead of getting a smooth finish you get a kind of a wavy texture that looks like the surface of an orange peel. This type of texture does not only appear on floors but we see it on all types of coated surfaces (like walls, doors etc).

In resinous flooring, the orange peel effect is not a necessarily a bad thing. Often it can be very desirable as it will produce a light anti-skid effect. However it can often become an issue of dispute between contractors and clients especially if clear expectations have not been set in advance of what the client will get.

Thixotropy is probably the most significant factor. Thickish products that flow slowly tend to have a harder time settling on the floor and are therefore are more likely to develop the orange peel effect. It is common to add solvents to make the product thinner. However using products with high solvents could cause undesired effects in other areas (like bubbles, unpleasant odours). Speaking of thixotropy remember that the temperature also affects the flow of the product. Hot temperatures will make the product fluid like water whereas cold temperatures make the product flow less. It is not just the room temperature that will affect the flow but also the temperature of the slab. I once mis-calculated the temperature of a very cold marble slab which led to all sorts of viscosity problems (Let’s just say that we had to re-coat the floor!)

The type of application tools used in epoxies is probably the other most important factor that will affect texture. For example if you apply the product with a thick wool roller, this will leave a clearly visible orange peel texture. Using a short-nap roller could decrease this effect, but one of the disadvantages of using a short-nap roller is that they tend to hold less product quantity and you end up applying a very thin film that could be prone to peeling and wear very quickly.

A compromise solution would be to apply and spread the product evenly with a squeegee and then have someone with spiked shoes back-roll the product with a short-hair roller to eliminate squeegee marks and get a uniform texture throughout.

The final factor that could affect texture is the condition of the underlying surface.
Sometimes the orange peel texture may have been formed during the primer coat. Adding any coat on top will simply magnify the existing texture. Likewise a very glossy surface could also trigger an orange peel texture as the fresh coat will not be able to bond properly due to lower surface tension!