Q.: We've seen several references to a concrete-cleaning device that removes elastomeric membranes, paints and coatings by flame blasting. Oxygen and acetylene are combined to produce a flame that is passed at a given height and rate over the substrate. This device appears to be suitable for an application we're planning, but we can't locate a manufacturer. Who makes them?

A.: The method you mention, flame blasting, is described in Guide for Selecting and Specifying Surface Preparation for Sealers, Coatings and Membranes (Guideline No. 03732), published by the International Concrete Repair Institute. However, the guide doesn't mention a manufacturer for the device you describe. It appears that most contractors who use this method make their own flame-blasting equipment.

Mauricio Estrada of Induworker Ltda., Santafé de Bogotá, Colombia, found a source in South America and says the equipment achieves good results. For more information, call Wilson Sierra at Agafano S.A. (571-2615277 or 571-4146955).