How To Prepare Your Concrete Driveway For Sealing

If you’ve made the decision to apply a sealer to your concrete driveway, one of the most important aspects of both choosing the product you use and the application process itself, is how you clean and prepare the area for sealing. It’s never a good idea to just apply sealer to any surface without preparation.

If there is a lot of surface cracks, or even chips and other damage, these will most likely need to be filled with a suitable patching product before the sealer is applied. This will most likely leave areas of the driveway with different colour patches where the filler has been applied, so in this case a coloured driveway sealer is a good product to use as you can cover over these areas to give a nice, even colour finish.

You will also need to look for areas of contamination from things like oil leaks, tyre marks, tannin or sap from trees, along with grime and mould. All of these will need to be properly treated and cleaned from the substrate before any sealer can be applied. Oil marks are a big problem and you will notice water beads and the surface doesn’t wet out properly if there is an oil stain. Bad stains may require a couple of treatments and using hot or boiling water with the degreaser is a good way to help break down these stains.

It’s also important to check if any type of sealer product has previously been applied to the surface. Not all sealer products are compatible with each other, and the application of a new sealer over the top of an existing coating that is not compatible will usually result in failure of the new coating. You should check an area off to the side or an area that is not in full sun or see much traffic if possible – often these areas still show signs of an existing sealer whereas the middle of your driveway may not show any residual coatings.

Newly laid concrete will also require a period of time to allow the substrate to fully cure prior to the application of a sealer, typically between 7-28 days . This will allow all traces of moisture to dry and the substrate to settle.

The best place to start when preparing the concrete for sealing is to treat any heavy or visible stains with a suitable product, like our HD Degreaser 950. Particularly tough stains may require a number of treatments to adequately remove the contamination, so be sure to allow enough time for this step before proceeding.

Next, it’s best to give the entire area a good pressure clean to remove all traces of dirt and grime. Be sure to use a pressure cleaner that is strong enough to do the job properly. Most small, electric pressure cleaners don’t have anywhere near enough pressure to do this, and also make the cleaning job very slow. Equipment hire companies have pressure cleaners that can do this job, or you could have a contractor come and do it for you. The trick is to point the pressure washer gun out in front of you at a shallow angle so the water blasts anything loose out in front. Aiming the pressure washer straight down at high pressure can actually damage the concrete and leave visible marks.

Some types of concrete finishes, including newly laid surfaces, may require an acid wash prior to sealing. This process helps to break down any fine or loose particles on the surface where they can be washed away with a pressure cleaner. Exposed aggregate is more likely to require acid washing as the process of exposing the stone or aggregate involves washing and brooming the surface while the concrete is still curing and this extra water can leave the surface of the concrete very weak and crumbly. Acid washing also removes any concrete haze from the aggregate and makes the stones appear brighter.

Once this cleaning and washing step is done, be sure to give the area enough time to fully dry before starting the application process. Any remaining moisture within the substrate will usually result in poor adhesion of the sealer or can cause cloudiness in the clear sealer.

Make sure you check the weather report before you start application, as it’s best that the area remains dry for at least 24 hours with most sealer products.

Remember, that applying a sealer to concrete is just like any other painting project where the old saying goes “it’s all in the preparation”. So, take your time to get the area ready and your sealer will last for years to come.