Early on in the project, architectural conservator Andrea Gilmore, who usually advises This Old House on historic paint schemes, dropped by the Charlestown house to assess the state of the building's brownstone lintels and sills. She told us that they were originally unpainted, and the wood of the bay window was covered in a brown sand paint meant to imitate brownstone, the effect being one of a unified masonry building of brick and brownstone. Climbing and probing, what Andrea uncovered is not particularly encouraging. Brownstone, a soft sandstone, is prone to erosion and, since it is a sedimentary rock laid down in horizontal layers, splitting along its "bedding" lines. Our beautifully carved lintels were worked parallel to these layers and put up on the building with the bedding lines vertical, just the ticket for water to enter, freeze, thaw and split them apart. Past attempts to patch them with some kind of concrete, and the application of paint, have done little to prevent their further decay. A few are in good shape, either because they are out of the rain, like the one beneath the bay window, or perhaps because their stone is denser. But the rest need help—or, more precisely, replacing. Not only are they losing their beauty, but the possibility of pieces spalling off and falling to the sidewalk presents a real hazard to passersby. Andrea suggested two possible solutions, each predicated on removing the decaying lintels. One: Call the Connecticut quarry that still produces brownstone, get some and find someone to carve them to match the existing. Expensive. Two: Choose the best of the existing lintels and make a latex mold of it, fill mold with cementatious mix, repeat, and paint resulting cast stone lintels to look like brownstone. Less expensive, but not cheap by any means. The Charlestown homeowners considered replacing the damaged brownstone, but that would involve using available or quarried stone that might or might not match the rest of the house and would require expensive carving. Pre-cast concrete offered a faster way to repair their home without breaking the bank. For the decorative and structural brownstone pieces, we used a rubber relief to create a mold of the damaged brownstone. Once we have a good mold, we work to accurately match the stone's color. Then it's time to cast the piece, achieving a good match with the original. The final product looks great, and helps restore an old house to its original splendor.