Most will have heard the term “Drydown”, possible dropped by the Club darkroom guru during a discourse on the mystique of print production. Let's try and penetrate the clouds that shroud this subject.

So what is drydown? Put simply, the phenomenon known as drydown can be defined as the change in visual contrast between a print in its wet, and dry state. That is to say; it finishes somewhat darker, when dry, than it appeared when first processed and washed. Very annoying!

The cause is basically that fibre paper absorbs water during development, which causes it to swell, and expand, and as a consequence it can shrink back to it original size during the drying process. This shrinkage causes the image bearing grains in the gelatine coating to be pulled closer together, thereby causing the darkening of the finished print. There is also a loss of Dmax as surface water evaporates from the print to further confuse the issue, but it is the paper shrinkage that is the main cause of our malaise.

Anyone doubting the considerable amount of expansion, and shrinkage involved should carry out a measurement of their handiwork in both its wet and dry state.

It is of interest that this manifestation doesn't occur to the same extent on resin coated papers, since their plastic coating ensures that they absorb very little water during development.

Fortunately there are several ways to manage the drydown effect.

Some advocate the use of a microwave oven to rapidly dry test prints or strips, so that only dry prints are compared, fine for the well-heeled amongst you.

As already stated the comparison of an image in both its wet and dry state will show that it will darken with drying, therefore reducing exposure will produce a lighter image, that will then drydown to the required tone, and contrast. Some experimentation is required to establish the reduction required to achieve the desired tone, but a 10% reduction in exposure time seems to be a good starting point.

Another approach is to prevent the paper shrinking back to its original size thereby preserving the original image tone. The technique for this is described below. An added advantage of this method is that it results in an exceptionally flat print, one that is ready for mounting immediately it is dry. Prints produced in this way, and left unmounted, will stay flat for many months provided that they are not subjected to high humidity, and are correctly stored. You will however lose a few millimetres off each side of your paper due to the final trimming required. Allowance should be made for this slight loss at the printing stage.

If you wish to try this method then you will require the following materials:

1. 15 to 20mm wide gummed paper tape roll, the brown paper type with a water soluble adhesive is required, not so easy to locate these days, but still available in most stationers or arts and crafts shops. Watercolour artists use it for a very similar purpose.