Using Concrete Sealer

You can use a concrete sealer on just about any porous mineral surface, not just concrete. A good concrete sealer will prevent the creation of surface dust, reduce the risk of staining and make the surface easier to clean.

Concrete sealers can also be used to seal and stabilize a concrete floor, or other porous surface, prior to painting it; which by reducing the porosity of the surface will also reduce the amount of paint required to be used.

Preparing Surfaces

The concrete sealant must be applied on to a clean surface, so you must at least give the surface a good sweep with a hard bristle brush to dislodge any lose or flaky surface material. If necessary then brush over the area with a softer brush to make sure all the finer surface material has also been removed.

Before brushing the surface you should treat and remove any grease or oil stains, to avoid sealing in any unsightly marks. If necessary use an emulsifying de-greaser; that can be rinsed off with water, before attempting to sweep the surface clean. If the concrete you want to seal is newly laid you’re recommended to wait at least 7 days before attempting to seal it.

There are two reasons for this wait. The first is to make sure the concrete has totally dried out to its full depth; and secondly - because on drying new concrete will form a brittle surface, that once fully formed needs removing with a very hard brush like a wire one. Concrete dust can be an irritant to your breathing system and eyes, so when preparing the surface for sealing please wear appropriate clothing and masks.

Applying Concrete Sealer

Concrete sealers can be bought in a variety of formulas. Whilst most will have a low vapor emission, if you’re working indoors with it have some windows or a door open to the outside. One of the formulas in use for concrete sealers are thermoplastic acrylic resins; as well as being an effective sealant they are flexible and less likely to crack under extremes of temperature.

Speaking of temperatures, read the manufacturers instruction for the ideal conditions in which to apply your concrete sealer, usually you’ll need a day when the temperature is between 10 and 30 0C. The sealer can simply be poured directly onto the surface and spread with a soft brush.

Obviously try and apply a sealer evenly and work it in until the surface has absorbed as much if the sealer as it can, without leaving any of the liquid lying on the surface. Coverage rates will vary from product to product, but you can reasonably expect to treat at least 30m2 with 5 liters of sealant; and one coat of sealer should be sufficient, unless you have a very porous surface.

Drying and Curing

Read the manufacturers instructions regarding the drying time for your concrete sealer. Whilst for most concrete sealing products you can walk on them after about 12 hours, if you can avoid walking on the surface for 24 hours you can be sure by that time the sealer has not only dried but is also fully cured.

The curing time will be dependant on the ambient temperature, usually best at between 15 and 30 0C, and there being adequate ventilation. You should wait at least 48 hours before attempting to wash the treated surface.

Cleaning Up

Concrete sealers can be very ‘sticky’ things. You’d be best buying a good brush to apply the concrete sealer with, you’ll need a good one or the bristles will come out and be left for all to see under the sealer; and then just throwing it away afterwards.

If the idea of throwing something ‘new’ away upsets you - you’ll probably need a Xylene based cleaner to remove the sealant from your brush. For a variety of reasons Xylene based products are not pleasant chemicals to work with, so personally I’d rather buy a new brush for a few dollars than risk my health.