Turning Play into Profits with Concrete Furniture

When you’ve got a busy concrete fabrication shop, it can be hard to find the time to create projects that no one has ordered. Yet that’s just what Lenny Cushing, a student from New Hampshire and owner of Zen Stoneworks, has done, and it’s paid off. He takes the time to save images, rough sketches, and architectural designs that he loves, and keeps a collection of them in his studio. These are what he draws on when he is inspired to create a new piece, whether it’s a customer-requested job or just something that he makes for the joy of it.

And rather than sticking with your typical countertop or vanity, Lenny embraces experimenting with entirely new things, is willing to take risks, and loves to see how far he can push his craftsmanship. He’s learned a valuable lesson: at some point, you just have to get out there, get your hands dirty, and see what you can do!

For the pieces pictured below, Lenny had to do a lot of experimentation with his molds and designs. The cantilevered bench was hard to calculate, because the pieces interlocked at angles. It was definitely challenging, but clearly worthwhile, as the project turned out beautifully. The more he tried to plan it out ahead of time, the more he realized how much had to be figured out as he went along (before casting, of course). Often a little trial & error in the initial stages of a project can save massive headaches once a piece has been cast!

Lenny and his crew are working with some experimental materials, trying new things which will allow for really interesting shapes and designs. He’s done his research and knows that there’s a huge market for artistry in furniture right now, and a design must be both beautiful AND functional. That which is pretty must still have a purpose.

We look forward to seeing what he’ll do next! You can check out more of his work here: www.zenstoneworks.com, or contact him at 603.319.8700.

Lenny attended CCI training in December 2009.

How to avoid ghostly mistakes in your concrete countertops

Sometimes lines appear in concrete countertops where the reinforcing seems to show through. This is called ghosting. Since it’s October, and we will be celebrating Halloween here in the U.S., I thought I’d write about “ghosts”.

Ghosting is most often caused by changes in the concrete matrix due to aggregate segregation, changes in the water-cement ratio, and other changes in the cement paste. Any changes in the cement paste affect how it cures, and this affects the appearance of the finished product.

The primary cause of ghosting is pushing reinforcing material into the concrete after the forms are filled, which causes a pumping action directly under the reinforcing. This pumping action disrupts and changes the cement paste, which in turn results in ghosting.

Another cause of ghosting is hanging the reinforcing in the forms and pouring the concrete through it. If the stream of concrete is split by the reinforcing but does not get a chance to remix below it, the aggregate gets pushed aside but the paste and cream flow back together. This causes a paste/mortar matrix change directly below the reinforcing that will cure slightly differently, resulting in ghosting.

A third way ghosting occurs is when reinforcing already buried in fresh concrete is moved or vibrated. The movement causes localized segregation, which in turn causes ghosting.

Ghosting demonstrated by deliberately pushing the reinforcing through the concrete


Ghosting in an actual installed project from the Hall of Shame. The reinforcing isn’t even correct! Outlining the sink – please!

Other surface marks that resemble ghosting can be caused by leaky forms, excessive form release agent pooled or puddled in the forms, and items left on the curing concrete surface (like sponges, soda cans, polishing discs and hand pads). Anything that traps moisture in or on the concrete in some areas while other areas of the concrete remain uncovered and allowed to dry will cure differently. Concrete that is moist longer will cure more fully and the color will be more intense in those areas.

Ghosting is NOT caused by the reinforcing being too close to the visible surface. The fact that the reinforcing is close to the visible surface does not cause any changes in the curing of the cement paste.

Unfortunately, once these surface marks occur, there is no way to remove them. Prevention is the only way to ensure that ghosting doesn’t happen.

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