By Andy posted March 14, 2009 | Views: 3868
Why Concrete?
Each new countertop material offers new possibilities to the designer and the consumer, giving the fabricator a broader palette to offer with ensuing profit opportunity. Concrete for countertops produces beautiful, honed surfaces that are wonderful to touch and complement other natural materials beautifully. The greatest single advantage of concrete is that it is infinitely formable and colorable; therefore, the only limitation in design is the imagination of the designer; any shape or form that can be imagined can be made in concrete, including 3 dimensional shapes.
Business matters - Each concrete countertop is a custom job and can be pretty profitable. Building tops for a typical kitchen takes a few hours a day over a five day period; material costs are low. Finished prices can start at $70-80 per square foot for a basic slab, with upcharges for specialties such as an integral sink, backsplash, fancy edge and the like; you can also pass through the costs of templating, delivery and installation. Some approaches require more specialized tools, such as vibrating tables and other devices, but expensive tools are not required. Although the steps in the overall fabrication process have similarities with other solid surface options, training is very important for a successful entry into the business.
Templating and Moldmaking - While concrete tops can be poured in place, the experienced fabricator generally brings the template back to the shop. Molds, as one-offs, are mostly made by hand, although we’ve heard of some fabricators digitizing the template and cutting molds out of styrofoam on their CNC machines. This may not work for complex molds: Countertops can have integral returns or backsplashes, drainboards, built in trivets, custom edges, an integral concrete sink or a very creative shape. The mold must have openings or allowances for sinks, ranges, faucets, drains, or overflows. Mold making is key to the fabrication process; it must be completely accurate. While some minor adjustments can be done at installation, concrete is HARD and its much easier to make it right to begin with!
Casting - Once the mold is built (against a non-porous surface such as melamine), there are three basic techniques for casting; you can hand pack, wet cast with or without vibration, or spray, and do it upside down or right side up, depending on the desired look. Concrete counter fabricators can make their own concrete mix or use a specialized bagged mix. Buddy Rhodes Mix can be hand packed to produce natural looking veined, ground or troweled surfaces; it or other mixes can be used for wet casting or vibrating, yielding a fine, even surface. Spray application of a face coat, coupled with GFRC reinforcement techniques, produces an extremely smooth, machined looking surface that often doesn’t need polishing. One can add additional aggregate, such as rocks, glass, seashells or nearly anything to the concrete to extend it, to make it ‘greener,’ or for design reasons. Inlay almost anything into tops during casting, as the designer dictates, or cast in gaps to insert items later, like a favorite tile or a metal trivet.
Reinforcing - The reinforcement depends on the chosen style of casting. Wet casters have generally used rebar or 3 or 4 inch welded wire. At Buddy Rhodes we’ve been partial to Ladur wire (a particular type of welded wire) for some applications and expanded wire mesh for others. Currently taking the concrete countertop world by storm is GFRC, or Glass Fiber Reinforced Concrete. This proven construction technology looks to be a great boon for concrete countertops, allowing thinner pieces at greater dimensions. We like it quite a bit, and have added these materials to our line. They also are available from other vendors.
Polishing - After casting, the top is allowed to set and reach the initial hardness required for polishing, then is removed from the mold. In our system we do it the next day; some methods can take up to three days. When using the Buddy Rhodes veined technique, the fabricator backfills with our color paste product at this point; for other looks a mortar-based slurry can be used to fill any remaining air holes. The amount of polishing depends on the look being sought. We use a hand held wet polisher with a series of different diamond pads; starting either at 50 grit or 200 grit depending on how much aggregate we want to reveal.
Sealing - Each type of sealer available has different characteristics (and none is perfect), so a range of considerations, both functional and aesthetic, determines the choice of sealer. The Buddy Rhodes system uses repeated light applications of a penetrating and then a repellent sealer, applying beeswax as a final coat (we leave some with the customer for occasional rewaxing). This produces a very natural, deep, stone looking finish which appeals to our aesthetic. Other fabricators may use coatings that leave an overlay of material on the top; these can be more impervious to staining (although the coating itself can stain or discolor in some cases) but has a very different look and style.
If your customers are asking for concrete, don’t be afraid to give it a try! There are many systems available along with training and information to make the successful transition to producing concrete countertops. Resources abound on the internet for information, products and training. Happy casting!
www.BuddyRhodes.com
www.ConcreteCountertopInstitute.com
www.ConcreteCountertops.net
www.BuddyRhodes.com/training_concrete_countertop.html
www.ConcreteNetwork.com
About the Author: Mark Gunther has been a partner at Buddy Rhodes Artisan Concrete since 2005; previously he was in the restaurant, magazine, toy, catalog, and international development businesses. He’s an active volunteer for good causes, and an avid bicyclist. He can be reached at mark@buddyrhodes.com; for tech support and more information check us out at www.buddyrhodes.com.