I'm constantly seeking to improve my photography. With over 4 years invested in digitising the Beattie collection, I think it's fair to say I've learned a thing or two. At the high end of commercial digitisation the big gun scanners use a glass drum and the negative is mounted onto the drum with a special scanning fluid. Historic negatives are not normally digitised this way for fear of damaging them. And of course glass plates can't be bent around a drum. So wet mounting (sticking the negative to glass with fluid) is not something that is used for this type of project. But that didn't stop me researching it and deciding if wet mounting had something to offer. Turns out that it did.
Some of the Beattie collection exists on 120 film. Where the original glass plate was lost, a high quality print was re-photographed on film. Ilford Fp4+ to be precise. So we have a lot of it and some of it is quite old and well worn. The acetate base (the "film") gets scratched with repeated use. One of the downsides to the very high resolution scanning process is that it reveals these scratches whereas the traditional darkroom printing, using an enlarger, does not.
The advocates of wet mounting claim that the fluid fills in the microscopic scratches in the film surface giving a better scan. The other benefits come from reducing refraction. Dry mounting sandwiches the film between two sheets of glass to flatten it. This means that you are photographing through at least one layer of glass. The more layers you put between the film and the camera sensor, the more chance of distortion.
So I decided to try wet mounting.
I got some excellent advice from www.scanscience.com and the wonderful Mr Dan Max who got me kitted out with appropriate fluid, glass and most importantly technique. This is a lot harder than it sounds because he had to ship "dangerous goods" internationally. The scanning fluid contains a flammable component so it can't fly, has to come sea and road freight.
The results are good. I can easily tell the difference between a wet mount and a dry mount scan. There are less scratches and marks but more importantly more detail and contrast. And the wet mount holds the negative much flatter than a dry glass sandwich. The process takes a bit longer but the results are worth it.
The photo (above) of Wineglass Bay is a wet mount DSLR camera scan with no retouching. Looks very good to my eye.