As with all of our concrete tanks, the inside casting is done with traditional, colorless concrete made of chlorine-free water, the same formula used for centuries in European concrete wine tanks.  The outer shell is composed of our revolutionary, new FiberCast concrete that is environmentally-sustainable, extra strong and absolutely beautiful. This unique combination gives maximum strength. The outer shell also permits the egg to be made in a variety of colors, because the pigmented concrete never comes into contact with the wine. We can even emboss your name or logo directly onto the concrete, making these intriguing tanks an added attraction for your tasting room or winery tour.