A lot of decorative concrete contractors believe that removing concrete sealer is one of the most difficult and most frustrating things they have to do. Generally, the materials that are used for the removal of sealers are hazardous, as they are hard to remove and difficult to properly dispose of and usually require multiple applications.
Removal is usually related to problems that result from its application or misapplication. One problem would be “frosted” sealer. This develops when the concrete sealer loses its attachment to the concrete. When it goes through the layer of air in the bond line, which is between the concrete and the sealer, light is diffused.
There are instances when the whole surface has a “milky” color due to the excess water contained by the slab. This water accumulated under the sealer as it was installed. Sometimes, installers put sealer when the temperature is too hit for the sealer particles to properly combine and form a film.
Whatever the reason is why you need to remove the concrete sealer, you must try the less invasive methods first. If only small areas have lost their bond with the concrete, you can scrub a solvent like zylol for the sealer to be dissolved. Once it dries, a bond with the concrete could be established again, with the area not appearing white anymore. You should make sure that the proper safety equipment is used when handling strong solvents.
Some examples of the stripping agents that can be used for removing concrete sealer would be alkaline strippers, silicone-digesting materials or solvents.
It is crucial to know first what kind of stripping agent you will be using. The instructions from the manufacturer would be able to advise you on what kind of breathing apparatus and protective clothing that you need to put on while applying them. If you will be working on a slab that is indoors, make sure that the area you will be working in is ventilated properly. Also, make sure that the pilot lights and fires are turned off. You also need to check what is required by the local regulations for the proper disposal of any residue. These requirements would help you to decide if you will be using a product that can be mixed with water so that it can easily be picked up or if you will just be scraping the used up material from the slab’s surface.
Remember to always first try it in an area located in an inconspicuous place. You could then proceed in the application as directed by the manufacturer. A lot of manufacturers recommend that the solvent-based stripping agents should be brushed on and not be disturbed as they work.
These stripping agents are rarely left in place for an hour before it is removed. On the other hand, the less time-sensitive alkaline strippers can be left for several hours.