• Q. I have an existing concrete sink that is in need of a fresh look- fixing pitted and worn concrete and new waterproofing, how can I do this?
pitted concrete sink need resealed
  • A.  This problem occurs when concrete is used that isn't as high strength as it should be, and when a low-grade sealer is used.   The whole surface could be re-coated with a Microtopping.  Or, the surface the concrete can be patched and re-finished.  The first step would be to either use a Stripper to remove all the old sealer, or just sand it down, Diamond Sanding Pads recommended.  Once you are sanded down to concrete, you can then apply a cement Slurry Patch product to fill in any pits, holes, rough spots.  You may need to repeat the slurry step a time or two to get it perfectly smooth.  When that is dry you can lightly sand smooth and then let it dry a day or two to harden.  You can pigment the slurry with Dry Color Powder to match the concrete, or you can try to just stain all the concrete and patched areas after with Concrete Stain.  If you didn't remove all the old sealer though, some areas of the old concrete may not take the stain  so you may get a little splotchiness to the color if it all doesn't get colored evenly- which is normal for concrete to look like, and often the sought after 'look'.  Some want a solid color though, and if so, the final step to seal the concrete you can actually mix in the Concrete Water-Based Stain with the sealer, and with 3-4 coats of the sealer it should be a pretty solid, even color.  The final step, sealing: XS-327 Sealer will protect the concrete, whether it's used clear, or pigmented with the stain.

  • Q. How much do concrete countertops cost?
  • A. Costs are two-fold:
    • One cost is the actual cost to make, for the DIY adventurer. Material costs alone vary, based on what products are added into the concrete mix (plasticizer, acrylic polymer, integral color, etc.), and what type of finishing is done (polishing the concrete, acid staining, type of finish sealer used, etc.).  The typical high strength concrete mix, colored, with a high quality concrete sealer, and melamine for creating simple forms, is in the ball park of $4-$7 per square foot of finished concrete.  Remember, this is a ballpark figure.
    • Cost type two; paying to have concrete countertops fabricated and installed.  Cost varies significantly by geographic location.  For example, Concrete Countertops may be available for $40 per sq. ft. in one area, and well over $100 per sq. ft. in another.  Supply and demand, local cost of living, costs of skilled labor, distance for traveling, all factor in to price.  Small jobs (such as a single bathroom) will usually cost more per sq. ft. than a large kitchen, due to time required to travel, bid, create, finish, and install just a small piece.  A fabricator of concrete countertops that is established, has a large proven portfolio, will usually cost more than another company just getting started, and more willing to sacrifice money in order to build reputation.  The best way to get an answer to this question is to contact a few concrete countertop fabricators in your immediate vicinity, and get a base price.  Remember, you may get some pretty large differences in price, even within one geographic area.  Try to request the exact same type of work (ie: if you request the countertops be polished from one source, and not another, your price comparison will be skewed).  You may want to view portfolios, samples, or best yet- anything they've done in a 'public' place that you can go examine.  The lowest price out there isn't always the best deal! 

  • Q. Why do concrete countertops cost so much? Why is some granite cheaper?
  • A.  Difficulty and labor primarily.  Most concrete countertop fabricators are artisans.  To be successful, they have to have perfectionist tenancies and an artistic emphasis.  Nobody likes installing concrete countertops.  While materials, for the most part, are relatively inexpensive for concrete countertops (especially if you DIY), the amount of time involved to make a countertop out of nothing is a large part of the final cost.  There is limited usefulness of having unskilled laborers when making concrete countertops, which means paying for skilled workers.  We've had dozens of customers that have made their own concrete countertops, and although they say they saved money and enjoyed the experience, paying someone to do it would be money well earned. Concrete has a cure time, so once countertops are 'poured', they require babysitting until complete. For pre-cast countertops, they tie up shop space until they are finished and installed.  Other countertop choices such as granite are available in varying grades, and thicknesses.  The cheapest ones are usually the ones advertised, and are the thinnest and most common (readily available) grades.  Concrete countertops give you something unique that you won't see another just like it in any model home.  The amount of customization you can get from concrete shouldn't be over looked either- think creatively, rather than just a normal 'slab' of concrete.

  • Q. When mixing concrete with Modified Acrylic Polymer (such as Duraplex) in the mix, why does it seem there are so many pinholes in the finished concrete or GFRC facecoat?
  • A. Typically this is the result of mold release, and if spraying GFRC Facecoat; gun pressure settings, spray technique and slump.  If polymer has been stored in direct sunlight or at high temperatures with the lid off, the de-foamer can evaporate out of the polymer, which will result in the air content of the concrete/GFRC mix to rise dramatically.  Nine out of ten times, mix temperature ends up getting too hot (above 74 F) causing a rapid loss in slump and pinholes in the concrete surface.  Keeping mixes below 74 F, using COLD water and/or ice in the mix to control temperature will help solve this issue.  Also, keep the lid on the polymer container during mixing, and out of direct sun or hot areas.

  • Q. What is Efflorescence, and how do I get it off my concrete?
  • A. In simple terms, efflorescence is left over dried salts on the surface of concrete or masonry. 
    • Cause: The salts can come from a number or sources- common ones are ground water that leeches into the concrete over time, and dries, leaving the salts behind.  The can also come from cement, or un-washed sand/gravel in concrete.  If the water used to mix concrete has salt content in it, then it can lead to efflorescence.  Efflorescence is generally not associated with precast concrete such as countertops, since they are usually much more controlled when being made, and not subject to leeching water from the ground once installed.  
    • Clean: Since efflorescence is usually just dried salt crystals, washing can remove it.  Often it will look cleaned off, until the concrete dries and it appears again.  You can brush the concrete with a stiff bristle brush vigorously, and then rinse with pressure.  There are a number of products available to help remove efflorescence, such as Concrete Cleaner And Efflorescence Remover.  Other possible solutions to remove efflorescence are to heavily saturate the surface with water, and then apply a solution of 1 part muriatic acid to 20 parts water to the area, scrub it well, and then rinse the surface.  Immediately follow this with a alkali wash of 1 part ammonia to 10 parts water, scrub the surface, and then rinse a few times.
Efflorescence in Concrete