For certain applications in glass processing it is necessary to know which side of the glass has been in contact with the tin during float glass production. This is easily achieved with the Bohle tin side detector · especially suitable for use with glass fusing · operated by 4 standard "AA" batteries · includes batteries and instruction manual Application: Hold the detector with the light emitting side below the glass, touching the surface, and switch it on . If the blue UV light turns milky, the side touched by the detector is the tin side. If the light does not change its colour or appearance, it is the air side. For additional testing security the test should be repeated - if possible - from the other side of the glass sheet.