We are familiar with oxalic acid as an active ingredient in many of the major deck-washing, wood-bleaching and paint-stripping products. We have not however heard of it being used solo for this type of cleaning application. Of the two manufacturers that we contacted that mass produce fiberglass shower receptors, neither had heard of this method and could not recommend or oppose it. We appreciate the fact that you were successful in your cleaning bout but are reluctant to recommend this method to others because of the many health hazards that can surround the use of an acid. Our problem is not with the use of oxalic acid but rather its use in a non-diluted form.

We suggest that if you attempt this in the future you consider looking for oxalic acid as part of a concentrate that can safely be diluted with water. You'll find that these product come complete with instructions for use and just what to do in the event of a problem. Finally, remember that rubber gloves, eye protection and proper ventilation are an absolute must when using these products.