I truly understand - it also destroys the physical compound structure of your bathtub. This is the old way of reglazing your old bathtub and although many companies still utilize this method (just because it works) there are alternatives available in certain places. My company, Total Refinishing, uses a newer, much better thermo - molecular system where the surface is prepared in a way which incorporates industrial cleaners. These cleaners can be used without golves, which is the easiest test - acids must be used with golves. Instead of a primer and glaze being used, as in the old way, this procedure uses an adhesive which, as it cures, molecularly bonds the material to the surface for an extraordinary finish.
In short, a great point wich can be circumvented by locating a company who utilizes the newer procedure. But, beware, many of the old styles are being called "New Adhesive" styles. The secret is the gloves.