Worfie, I don't know if this is too late to help, but we got out our dehydrator to do some herbs last night. Fresh currants isn't a fruit that is widely available in the US, they are not listed in my instruction manual. For the category "berries" is says "Preparation: Leave whole. For wax-skinned berries pre-treat by crazing. Test: leathery. Time: 10-15 hours." I didn't know what crazing meant, I found it under "Blanching". "Blanching, as a means of pre-treatment, can be done either in boiling water or by steaming the foods. This pre-treatment is sometimes referred to as "checking" or "crazing'. You can use this method most effectively on tough-skinned fruits (sometimes having natural protective wax coating) such as grapes, plums, cranberries, etc. By boiling fruits in water for 1 to 2 minutes, the skin "cracks" and allows the moisture to more readily escape, thus the drying time is faster." It them goes on to describe methods of blanching. There is also a section on dipping in sulfites to preserve colors.