Printing: Printing can be a rather slow process; sometimes using a test strip is not always accurate for calculating the correct exposure period for the whole image.
Certain areas such as skies often require a much longer exposure time than darker areas such as shadows and darker tones.
At the same time, the darkest tones in an image can often require a shorter exposure time under the enlarger.
This is where the dodging and burning technique comes into play.
Dodging and Burning: Dodging and burning allows you so control the tones on certain areas of the paper.
When you print your first image in the darkroom you will probably notice that there will be areas nicely exposed, but there will also be areas lacking in detail (blocked up shadows or blown out highlights without any detail).
This commonly occurs with skies and shadowy areas.
An example of good use of the dodging and burning technique can be seen in the pictures of the vintage car.
Once I had the average exposure time available to be from working on the test strip, it was time for me to investigate the exposure times needed for various areas of the image.
The first image was slightly under exposed onto the paper so I had to increase the overall time the paper spent under the enlarger (the exposure time was 52 seconds at f16).
I increased the exposure period to 90 seconds to increase the contrast and bring some more detail into the chrome areas.
The overall tones of the image greatly improved but there were still many highlights showing, particularly with the chrome and the sky.
The darker areas were turning out a little too dark so I set the overall exposure time back to 75 seconds.
I was then happy with the tones of the car itself.
It was then time to work on some dodging and burning.
Here is an explanation of both terms.