To ensure your resin coating provides a good looking, long lasting finish, proper preparation is essential. Just like with painting walls, doors and radiators inside your home or building, cleaning the surface, mending any cracks and dealing with damp before coating a floor with a resin product needs to be done before you open your paint.
Not all floors need the same level of preparation, for example a brand new concrete floor based somewhere relatively warm and used for low traffic purposes will need less preparation than a flaky, damp floor which supports heavy machinery. Follow the steps that apply to you below to ensure the surface you’re coating with epoxy resin clean, dry and free of dust, dirt, oil, surface matter and in good shape for your coating to stick.
Manually cleaning a floor prior to coating
No matter the age of your floor, dust, dirt and loose or easily crumbled material will have accumulated on the surface. Getting rid of this will help the coating bond to the surface, help the coating stretch further and make it easier to apply in the first place. We recommend starting by sanding or wire brushing your surface which will key the surface well and also allow you to inspect the floor’s condition as you brush. Next, sweep up with a broom or vacuum cleaner, working from the far corner towards the door.
Acid etching a floor before coating
Larger floor areas may be too time consuming to clean manually and have too many large deposits to remove with a wire brush or sand paper. Acid etching products can be used instead which uses diluted hydrochloric acid to break down the flaking or weak surface layers and leave a roughened surface which helps paint or sealer adhere to the surface. Take precautions to protect your skin and eyes, dilute according to the level of etching required, apply the acid solution, scrub with stiff bristle broom or power scrubber and rinse off with fresh water.
Rapidly cleaning a floor with solvents
When used in well ventilated environments, solvent cleaners can be one of the quickest and most effective ways of cleaning rubber, grease, oil and marks from a concrete floor. Using a blend of solvents in place of acid means the surface dries very quickly when turnaround times are very short or repairs are extensive. Inhaling solvents or getting these on your skin can be very harmful so use correct breathing apparatus and protective equipment.
Degreasing Floors and Removing Oil
Over time, grease, oils, fats and tar can build up on the surface of your concrete floor, brought in and spread by shoes, vehicles, spills and improper storage of equipment and liquids. These can be removed using an industrial strength degreaser which is diluted with water then sprayed or poured and brushed onto the surface. After 5 minutes the degreaser will have penetrated the surface, cut through the layers of contamination and be ready to be scrubbed off, wet vacuumed away or pressure washed to leave a clean surface.
It’s important to prime the floor with a resin primer straight after degreasing as any oil which was previously beneath the surface will rise to the top and blemish the freshly cleaned surface if not captured and absorbed by a layer of priming.
Cleaning a concrete floor with machinery
Mechanical cleaning is best carried out by trained operators as this reduces the chances of removing too much of the floor, causing permanent damage. Using machinery to prepare a floor can also release dust and other dangerous particles which must be carefully extracted during the cleaning process to stop damage to lungs and ensure the coating sticks. Professional cleaners can be found on our Approved Installers list and will use a combination of 3 mechanical cleaning methods.
Shotblasting a concrete floor
A vacuum assisted shot blaster is used to remove weak concrete, dirt, contamination and anything that stops the coating forming a bond. A shot blaster quickly strips coatings in large areas and the connected industrial vacuum sucks in 95-99% of the dust. This makes shotblasting environmentally friendly as chemicals are not required and means harmful paint particles do not enter the atmosphere. By blasting an abrasive substance in a controlled pattern and direction, the concrete surface and contaminants are picked up and land in a recovery chamber. This can cause blast lines where the blast areas overlap so for projects where only thin, single layer coatings are applied, shot blasting may not be appropriate.
Scarifying or Scabbling a concrete floor
A floor scarifier is a versatile machine which can be used to scarify (cut and tear the surface at high speed), grind and clean the concrete using a range of plates, shoes or discs which are fitted to the rotating base of the scarifier. These machines are also known as surface planers or milling machines and are also available in a rotating drum style which uses tightly packed cutters.
Scarifying a floor is very quick but a very loud and dusty process, which produces strong vibrations and can mean that controlling the machine is difficult. We would recommend using an approved installer to do the hard work for you, including removing the disintegrated concrete which can be a considerable job as scarifiers can remove up to ¼ inch of concrete in a single pass.
Floor scabblers achieve similar results but use a compressed air mechanism to hammer multiple pistons onto the surface. This creates a rough surface which is ideal when preparing for a non slip use, for example in barns which hold cattle or other animals and often have a wet or muddy floor. A scabbled floor can also help forklifts and trucks grip the surface as the grooves and ripples provide more traction, particularly in wet or icy conditions. Again, scabbling is best performed by a qualified professional who can safely and precisely remove only the top layer of concrete to reveal the fresh layer beneath.
Industrial Grinding of a concrete floor
Walk behind diamond grinders and handheld grinder systems are best for producing smooth, flat and swirl free finish on a concrete floor. These use twin heads to grind away defective coatings, rough layers, pitted or powder floated concrete ready to seal or coat. They can also be used effectively to level out the floor prior to painting, particularly when multiple slabs have been used which do not currently match up with one another. They can also polish concrete floors and terrazzo tiles which are in generally good condition or remove ultra fine layers such as non-slip film or spray.
Any small or inaccessible areas can be finished by a handheld diamond grinder and an industrial vacuum used in conjunction to ensure the area remains as dust free as possible.
Due to the amount of dust produced and the intensive physical demands of the process this is a significant undertaking which also requires the correct selection of the specialist diamond grits. If you are grinding the floor yourself, speak to a specialist before beginning who will be able to advise you on the correct discs, diamonds and methods for your particular floor size, condition and usage.
Dealing with rising damp
Some concrete floors may have a few problems with rising damp where the Damp Proof Membrane has been damaged or, in older buildings, is missing altogether. You may only become aware of this after removing the top surface so take a moment to check for and deal with any damp patches. This involves taking the following steps:
1. Checking for damp.
Start with visually inspecting the floor for any damp or wet spots. Be sure to check the whole floor as moisture conditions can vary greatly depending on proximity to windows, vents, machinery, exterior walls, expansion joints and any areas where holes have been drilled or walls removed. Make sure you check more than once as damp levels can vary. Moisture meters can be used to digitally monitor the accumulation of moisture on the surface or in any cracks. Just set the device to read concrete and place the pins or detection surface against the floor for several seconds. There are different standards and gauges depending on guidelines and manufacturers so refer to the manual for an indication of the ideal level.
Damp can also build up over time so you can also temporarily trap moisture to help assess your level of damp over a 24 hour or longer period. Tape down a thick polyurethane sheet to the floor and check it is completely sealed. Leave it there for 24 hours with the building under normal temperature conditions and then take up the sheet. If beads of water show on the underside of the sheet this indicates there is water vapour in the concrete which will cause problems with the adhesion of coating or screeding.
2. Eliminating rising damp
If you’ve recently laid a new concrete floor, make sure you allow sufficient drying time before coating if possible. Allow 1 day for each millimetre thickness of the concrete (approximately 1 month per inch). You can speed up the drying by using an aqua vac to help dry up the liquid.
Next, coat the floor with a Damp Tolerant Epoxy Primer. This is an epoxy resin primer designed to provide a complete seal and hold back rising damp in dry or damp conditions and old or new concrete. This means it is usable on concrete with up to 60% moisture content. It can be used on rough or porous concrete but’s a good idea to fill any major cracks or holes before priming.
Surface damage repair and filling cracks and joints
Concrete is not a flexible material so cracks can form when pressure is applied, or when temperature causes the concrete to shrink or expand. This shrinking and expanding can be controlled by including expansion joints which help accommodate expansion in set grooves.
Most cracks can be repaired by pouring an epoxy crack filler into the crack itself and allowing 4-6 hours for the liquid to set and harden. Be sure to remove any dust of fluff from the crack before filling so the epoxy compound can bind to the concrete and pour in slowly to achieve a level finish which is stronger than the original concrete.
Larger holes (over 10mm wide) are best repaired using a concrete repair compound which cures to 3 times the strength of concrete. This is available in a selection of colours and pack sizes so the repair matches the original and reduces waste. The formula is fast drying in just 6 – 8 hours but this does give the opportunity to trowel down to a feather edge so the compound does not need to be trimmed, cut or chipped away and the finish is smooth or level. Like the crack filler, the repair compound can be applied directly to the hole or crack so any dips or grooves can be filled in without gaps.
For emergency repairs or specialist situations like floors with high levels of oil or moisture, Epoxy Resin repair mortars have been specially designed. Some set in just one hour, others are tolerant to oil and grease whilst some can be used as soon as any standing water is cleared away. These are available from the Floor Repairs and Fillers section of the site with fast delivery.
Once your floor is repaired and prepared, you’re ready to start the painting process. View our Applications Guide for everything you need to know about buying, mixing and applying an epoxy resin floor coating.