Our coffee is washed or wet milled, which describes how we get from fruit to parchment. Dry milling follows wet milling. Here’s a well-written article explaining about washed coffee.
… with a washed coffee, you are tasting the coffee itself – the origin, the coffee variety, the terroir – and not the impact of the processing method.”
Coffee gets wet milled the same day the fruit is picked. The fruit is put into the hopper, and any floating fruit (inferior quality) is skimmed off. In the next step, the pulper extracts the coffee seeds (the beans) which then go into a fermenting and rinsing tank to remove the remaining mucilage. After pulping, parchment ferments in a tank overnight before being spread on the sun deck to dry.
The beans are spread out to dry under a covered sun deck and are periodically turned. They dry at least overnight and maybe longer, depending on what coffee is in the pipeline to be processed after it.
Later the beans get mechanically finish-dried to a specific moisture content for quality consistency. The beans are still inside a thin, paper-like husk, and the beans are referred to as parchment coffee, or parchment, at this stage.
Up to now, the beans have been dried from the outside of the bean, in. By letting the coffee rest at this parchment stage, the moisture gets a chance to equalize throughout the bean. The parchment rests in a light-, temperature- and humidity-controlled area. How long it rests is another one of those tweak-able variables. Most of the moisture probably equalizes in a matter of days, but some people like it to rest a minimum of 60 days.