We are all familiar with the problem of placing a slab and then discovering the next morning that some child has scratched a name in it. My problem is just the opposite. I have a slab approximately two years old on which I wish to inscribe several names and dates in such a fashion that it will be as permanent as a name scratched in plastic concrete which was allowed to harden. Can you tell me how this might be done?
The most effective method might be to cut the desired wording out of a large rubber sheet, place the sheet over the concrete and sandblast the letters revealed. People who do this kind of work on gravestones might be available. Another method is to saw out a small 1/2-inchdeep rectangular or circular area and set in a brass plate using epoxy resin. The brass plate would be engraved or cast ahead of time. A third method involves acid etching. It can be done without any special equipment, just a few hand tools and simple materials, but is more timeconsuming and somewhat hard to control. The area to be inscribed is coated with paraffin and a small paraffin dike built up around the edge. Letters are then cut out of the paraffin coating and diluted muriatic acid about 1 part acid to 3 or 4 parts water poured into the area. During the exposure to acid the letter areas have to be brushed lightly and continuously with a soft-bristle brush to ensure that no residual paraffin prevents the acid etching. The brushing also facilitates agitation to bring fresh acid into contact with the concrete surface. Care has to be taken not to disturb the edges of the letters so that the acid cannot attack the concrete outside the letters. When the acid is spent and no longer bubbling the liquid should be rinsed away across the surrounding concrete onto the soil. One or more additional treatments may be necessary to get the depth of etch desired. The first of the three methods is probably the best and the third the poorest.