Concrete sealing has become a popular option for residents and business owners alike. Used to seal driveways, garages, pathways and flooring, it is great for increasing slip resistance, protecting concrete surfaces from deterioration and improving ease of concrete cleaning. However, sealing can backfire for a number of reasons and this can rarely be resolved just by applying another coat.
When a concrete sealer does not look or meet your expectations it may be that your sealer has been over-applied, applied in below par weather conditions or the result of build-up from too many coats.
Quickly Please Cleaning Services takes a look at some of the most common problems and offers helpful tips for fixing them.
Concrete sealer has white or cloudy patches
This can be caused by excess moisture on the concrete’s surface before the sealer is applied. It might also be the cause of environmental conditions affecting the drying process during application. Water-based acrylic sealers dry by a process called coalescence in which the water and solvent evaporate and amalgamate. If the temperature is too low or humidity is too high, the coalescing solution will evaporate before the water has a chance to, causing the sealer to dry powdery. It is always important to investigate the required temperature and humidity before applying the sealer.
The solution? You can scrub thinners into the affected areas to reactivate the sealer and with luck it will reactivate the sealer and hopefully allow moisture to escape. You may have to continue this process a number of times. However, if luck is not on your side, you might need a stronger reactivating solvent or in the worst-case scenario, the coating may need to be stripped and reapplied.
Concrete sealer’s surface has white deposits
Known as efflorescence, white salt deposits are produced during the curing process and rise to the concrete’s surface as a result of evaporation.
These white spots could also be the cause of water-soluble salts in groundwater penetrating through the concrete under hydrostatic pressure. When there are very high concentrations of groundwater salt the sealer can become flaky in small areas following the crystallisation of salts between the concrete and sealer. This occurs when the concrete has not been prepared correctly and the sealer does not mix with the surface properly. White deposits are normally found close to garden beds or in areas where the hydrostatic pressure of groundwater is high because of ground slope or level differences.
How can we fix this? As the salts are normally water soluble, we can often remove them with water. A weak solution of 100 parts water and 1-part hydrochloric acid may assist in the cleaning. Flush the area with this solution and scrub thoroughly.
To avoid the appearance of salt deposits you may need more than one or two coats of sealer, especially if the ground moisture is hydrostatic in nature and contains salt. In most situations three or more coats will prevent salts, so long as the first coat grips adequately.
Solvent-based sealer is peeling, flaky or has turned white
There are a few reasons why the solvent-based sealer turns white. The first is that the concrete surface is wet, fresh or contains bleed water. When this happens, the concrete sealer does not attach to the concrete surface but instead floats on a trapped film of water. The second reason is that the seal application may be too thick. Thick coats or a build-up of sealer after numerous applications over the years, will cause moisture to become trapped under the sealer. Sooner or later, the sealer will lose adhesion from the concrete. The trapped moisture and air between the concrete and sealer has an index of infraction so that the concrete sealer appears white to the eye. Eventually the sealer will flake or peel off the surface.
To avoid this from happening, follow the manufacturer’s recommendations regarding the number of suggested coats and coverage rate. Alternatively, call on Quickly Please Clean Services. We have state-of-the-art equipment and processes to avoid this and other problems from happening.
Sealer has silvering flaking
If you scratch the sealer in any area and it appears to flake off, this normally indicates an adhesion problem. In this case you will need to strip the whole area and reseal or use a seal repair solution.
Sealer is blistering or bubbling
This normally indicates a heavy application of sealer. Freeing the gas from the concrete’s surface when applying the sealer should allow for free movement through a thin, wet sealer film. But what does ‘thin’ mean in this case? One coat of acrylic sealer should be approximately 5 mils thick when wet. It decreases to 2 mils when dry. Bear in mind that a sheet of copy paper is about 10 mils thick, and a credit card is 120 mils thick. This gives you an idea how thin the sealer should be. When concrete sealer is applied too thickly, the air captured can’t escape and instead forms bubbles in the surface.
Bubbles also occur when the application is done in too humid conditions, or if the concrete is in direct sunlight. The sealer’s surface will dry too quickly before all the solvent has had time to evaporate. The solvent’s pressure trying to evaporate will form bubbles in the surface. Hence, it is best to apply sealers during the cooler part of the day, and when the concrete is not in direct sunlight.
If you notice that only a few bubbles are visible you should be able to knock them out of the surface. But if numerous bubbles are obvious, you could apply another coat when the surface is cooler.
Sealer is stained from leaves, oil, tyres, fertiliser, etc
Most concrete sealers are produced with acrylic polymers which do not provide great resistance to chemicals or stains. Consider applying an epoxy or urethane coating solution for more durability. But ensure the coating is appropriate for outdoor concrete before applying.
Concrete is blotchy and/or dark after the application process
Many acrylic sealers will darken concrete and create a glossy shine, sometimes giving the concrete a ‘wet look’. Because every slab of concrete is unique in texture and colour, it is difficult to predict the concrete’s colour after application. The combination of mix design, use of chemical admixtures, porosity and finishing techniques are just a few components affecting the concrete’s colour. Sealing often deepens the true colour of concrete and highlights the variety in surface texture that derive from floating and finishing. Sealers also accentuate the grain or texture of concrete like varnish does wood.
If the variety in concrete colour after sealing is a concern, do a small test application of a film-forming sealer to see if you are satisfied with the colour change or use a penetrating water repellent sealer.
Quickly Please Cleaning Services has a team of talented professionals who will do a sterling job on your concrete sealing so that you will not have to confront any of these problems. While providing protection against common spills, oil stains and environmental elements, we can enhance the colour, texture and contrast of your concrete’s surface with our large range of high gloss and matte sealers.
Our sophisticated equipment, processes and nanotechnology-based products remain unparalleled. We always ensure we complete the job to your specifications and budget.
Find out more from our team of experts and get in touch with us today.