Epoxy is often chosen because it gives a smooth finish.
Take a look at the picture of the floor surface above, the epoxy finished coating 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.
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 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.
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.
Thixotropy (the material will reduce its “viscosity” caused by large shear forces. For example, a mixing rod creating shear while mixing)
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 odors). Other way, the evaporation speed of added solvents is also a factor to consider when the coating applied at different thicknesses will have a different drying time and of course, will greatly affect the flatten ability of epoxies in large areas.
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.
I have found that the best application method for minimizing orange peel texture in thin coats 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 smooth finish. 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 (and/or any other un-expected effect) 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!
Concluding I just want to say that each contractor needs to do his own experiments with his own staff, his preferred tools/ application method 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? Please share your opinion for the best way to minimize the orange peel texture!
Please contact us – Euro Paint Vietnam Company – for product advice and optimal solutions for the Epoxy Flooring of your needs.
