Light boxes are used to view photographic negatives. They utilise a brightly lit white background that enables the viewer to more easily see all the details of translucent film. This is important when verifying that a negative does not have any imperfections before using it to print pictures. Light boxes can be purchased through photography supply stores. However, with a few supplies, you can make your own light box.
Purchase a metal picture frame with a good stand. A standard picture frame fits photographs that are 8 by 12 inches. Since you will be using this for photographic negatives, this size will be fine to start. You can buy metal picture frames cheaply at local second-hand stores.
Obtain a white fluorescent bulb complete with ballast and electrical plug-in. The light, when inserted into the ballast, should not be longer then the length of the picture frame and should fit into the cardboard box you will be using.
Go to your local home and garden supply store and purchase a piece of frosted glass or white translucent plastic. If the glass or plastic does not fit the metal frame you have, ask the store to cut it down to size.
Slide the plastic or frosted glass piece into the holder slot of the picture frame.
Find a cardboard box that has an opening a little smaller then the picture frame.
Paint the inside of the cardboard box white so that the light reflects off of the sides. Let the cardboard box sit until it is dry.
Cut a hole in the side of the cardboard box near the bottom.
Place the light with ballast into the box so that it faces up and pull the electrical cord through the hole you just cut.
Set the picture frame on top of the cardboard box.
Plug the electrical cord into an outlet and turn the ballast on if needed. Some ballasts will turn on right when they are plugged into an outlet.
Lay your developed negative on top of the glass with the light turned on for best viewing. You should be able to determine whether there are any water spots that need to be washed off or whether there are any imperfections in the negative itself.
If the surface of the light box gets too hot, it can damage your negatives. To avoid overheating and possibility of burning, never leave the backlight on when the light box is not in use.