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Basic Darkroom Techniques: Edge Burn in
When you make a print, you may notice that the edges don't seem to be as dark as the center, this is a phenomenon of printing related to the distance light travels from the lamp to the paper.
This drawing illustrates the point.
The distance travelled by the light to the center of the paper is less than the distance travelled to the
corners. You know that if you raise the enlarger you have to increase the exposure time, this is the
same principle.
What is the solution to this dilema?
Burn in the edges.
- Cut a piece of cardboard with a jagged edge, large enough to hold comfortably between the enlarger and paper and be able to cover the entire paper. I used a 8x11 sheet of cardboard from the box that photographic paper comes in.
- The jagged edge will help to prevent hard lines in the print, just like doing other kinds of burning in. I used a pair of pinking shears to create V-shapes on one edge of the cardboard.
- After you have made your exposure, burn in all four edges of the print, one side at a time, by moving the
cardboard towards the center, giving the edge more light, then moving it back to cover the paper completely.
I hold the cardboard about 1/2 way between the enlarger and the easel, and usually use 1/10th of the exposure time for the edge burning. You can calculate the amount needed, based on the angles and heights and stuff, but I find that 1/10th is usually pretty close to what I want. Here is another area you should experiment.
- You might want to compare two prints, one with edge burning, the other without, after they are both dry, to see the effect.
Have fun printing!
