ask big al

Applying densifiers to concrete in an even manner can be achieved by wiping off excess liquid with a disposable shop towel. This will prevent pooling and a cloudy appearance. The cloudy look is caused by crystals that are bound to the concrete and can be removed by a light sanding with very fine sandpaper. Sanding in one spot may cause an uneven look that may be unsightly. Try to burnish off the excess as gently as possible in a circular motion. You may need to feather the edges of the sanded area. If a sanded spot proves to be too much of a distraction, try a sanding of the entire concrete surface.

Please let Big Al know how this works!

Big Al has the fix for your concrete countertop. The repair is similar to what the craftsmen at Alpha Stone Concrete perform when grinding a concrete countertop. A pigmented slurry can be worked into the affected area and sanded smooth. Portland cement is mixed with concrete polymer to fill small voids in the concrete. Fine aggregates can be mixed in for larger, uneven ares of concrete. Mix concrete pigment with your cement in the proper ratio using a kitchen scale for accuracy. You may need to contact your supplier to find out the correct measurements.

back to the grind,
Big Al

Hi Terry,
Big Al is sorry to read about you scratched concrete floor. The remedy for the scratches will depend on how you intend to finish the floor. Concrete usually has a thin layer of cement paste that contains very little aggregate. It's smooth or textured surface is is the canvas for acid staining or is beautiful in a natural state. If you try to ease the scratches by sanding or grinding you will start to expose the underlying aggregate. Shallow grinding will reveal fine sands and deeper grinding will show the larger stones. The bottom line is this, what ever you do to the concrete will change it's appearance. There will be a light area if the floor is to be acid stained. It is often better to leave it alone and use a busy pattern with the acid. The other choice is to wire brush the entire floor to make a uniform pattern.

good luck,
Big Al

Hey Stephane,

We have a method for putting sealing countertops and concrete objects that is time and labor intensive but gives great results! We cut our sealer with water and apply it with a microfiber cloth over a week or so. We have the cloth wet with sealer and hand work it into the piece, allowing the sealer to penetrate deep into the concrete. The concrete will darken when applying the sealer and lighten when the sealer cures. The first coat is very important because each application will inhibit the sealer from penetrating. The last coats, 7-10, are topical coats that cross-link with the other coats.

1. apply sealer liberally to the concrete piece working it in random, circular movements.
2. make sure that the sealer has penetrated to a sufficient depth.
3. wring out the microfiber cloth and quickly wipe down the piece in random, circular movements.
4. repeat step 3

Hi Pierre,

The USGBC does not certify products for LEED. They certify buildings based on six different areas. Concrete counters have characteristics that apply to some of these categories. The use of concrete counters and other products may qualify your project to earn LEED points. Architects and LEED Accredited Professionals (LEED APs)can give you straightforward answers about LEED certification on your project. Different concrete counter craftsmen have varied methods of producing a "green concrete countertop" and some may be more environmentally friendly than others. Please keep in mind that countertops, be they concrete counters or other solid surface materials, are just a small part of most projects and their contribution is usually small as well. Concrete counters are like the cherry on top of your project, a piece of art in your kitchen.

Good luck on your project,
Big Al

Fibers can be used. We use fibers in our countertops and formed objects. The finished surface should be free of fibers. Big Al knows that the care that goes into pouring, trowing and curing a concrete slab has a big effect on the final product. Slabs that are poured on hot days and dry out before the concrete is cured can cause some interesting things to happen with the acid stain. The acid stain is mostly water and water is the one thing that the dry concrete craves to continue it's hydration. Once the concrete has the acid applied it resumes curing. This can cause an uneven appearance. An additional coat of acid can even things out but that can add a day to a project. Big Al suggests talking to you contractor about keeping the concrete slab wet during the initial curing phase.A good article on concrete slab curing can be found here.

http://www.concretenetwork.com/concrete/slabs/curing.htm

Always,
Big Al

Hey Char,

Big Al has used lots of cleaners on concrete countertops over the years. I have found that most of the time the stain is in the sealer and has not made it to the concrete. Big Al's philosophy is to use the most gentile method first. The most gentile abrasive cleanser that Big Al uses is baking soda. Baking soda is alkaline, works great and cheap! Any household cleanser that has the word gentile on the packaging should work. Big Al works the area dry or mixes in a little water to form a paste. Big Al has used soft scrub with bleach to remove strong stains like yellow mustard. Cameo and Bon Ami are good choices.

keeping it clean,
Big Al

Big Al loves cooking outdoors year round. A concrete countertop in your outdoor kitchen can be the centerpiece of your space with very little effort. The guys at Alpha Stone Concrete have made concrete bars and concrete countertops that have braved many New England winters and they still look great!

The most durable concrete is made with just the right amount of water in the mix. A properly made concrete countertop is free from cracks. The winter freeze-thaw cycle can make a tiny crack a big problem. Alkaline resistant glass fibers as well as polycarbonate fibers can help prevent cracks too. A ground surface is more durable, less prone to staining and is easier to repair. Proper sealing during the year will keep your outdoor kitchen looking new.

Hi Elaine,
Often when a concrete countertop is stained it is only the sealer that has the stain. Try a mild abrasive cleaner. Use it as dry as you can to abrade off the upper layers of the sealer and apply more sealer when the stain is gone. Florescent paper like sticky notes are really prone to bleeding and staining. However, the bright color does fade over time.

Please let me know how this works out.

thanks,
Al

Thanks for asking Big Al this question about epoxy and urethane sealers. If you ask someone that hopes to make a buck or two off you , they will sing the praises of their products and tell you how many satisfied customers they have.

Just yesterday the guys from Alpha Stone Concrete were down in Manhattan installing a concrete sink. To our surprise, there was another concrete countertop specialist at the job site repairing the countertops in the kitchen. These countertops were sealed with epoxy and urethane and had many scratches. We learned from our many experiments with these types of sealers that they often peel and tear away from the concrete over time. Surfaces with a ground finish often fare better than others.