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 also 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.
There have been times where I wanted a rather smooth surface and I got an orange peel texture. And there were other times where I deliberately wanted an orange peel texture but I got a smooth surface instead! So after years of trial and error I have identified some key factors that contribute to the orange peel effect in epoxies.
Let’s start off by mentioning that orange peel effect tends to appear in thin coats like top-coats or floor paints. The easiest way to avoid this texture would be simply to apply higher build coatings over 1-2mm (like self leveling coatings). But as there are several reasons where you might want to avoid a thick coating, in this article I am focusing on the factors that will affect the texture in thin epoxy coats
Viscosity is probably the most significant factor. Thickish, high viscosity products tend to have a harder time settling on the floor. Therefore they are more likely to develop the orange peel effect. It is common to add solvents to make the product thinner and to therefore reduce the viscosity. However using products with high solvents can cause other adverse effects in other areas (like bubbles, unpleasant odours). Speaking of viscosity remember that the temperature 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 viscosity but also the temperature of the slab. I once did not take into account 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 tools used in the application of epoxies also play an important role. If you apply the product with a roller, thick wooly rollers will leave a larger intense orange peel effect compared to short-nap rollers. However one of the disadvantages of using a short-nap roller is that they tend to hold less product. You could end up applying a very thin film that would be prone to peeling and wear very quickly.
A compromise solution would be to apply and spread the product evenly with a squeegee. Then have someone with spikes shoes back roll the product with a short-hair roller to eliminate squeegee marks. This should help you get a uniform texture throughout.
I have found that the best application method for minimizing orange peel texture is using an airless spray gun. However properly using and maintaining airless equipment is an art in itself and only experienced staff are capable of getting a proper texture. Lots of things can go wrong when applying epoxies with a spray gun, so make sure you know what you are doing!
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! (sounds a bit counter-intuitive doesn’t it?)
Concluding I just want to say that each contractor needs to do his own experiments with his own staff, his preferred tools and the products he chooses to work with. In each project prevailing conditions (substrate, temperature etc) will differ. And if the client insists on a very smooth finish the best solution is to upgrade him to a self leveling floor coat.
So what are your experiences? What in your opinion is the best way to minimize the orange peel texture?