I can smell it. ☕ Kindly explain one thing before I Google it...what is "washed" coffee?
I have only ever come across these descriptions of what are referred to as "washed" versus "naturally dried" coffees in descriptions of Ethiopian coffees, although each process may be used (and semi-dried certainly is) elsewhere in the world.
Just over a year ago, I spent a year deployed in the Horn of Africa which entailed frequent flights to and from Nairobi, - both to and from Europe, and to and from other places within the Horn of Africa - as Nairobi is one of the main hubs for the region (and the place where many international and diplomatic bodies and organisations have their regional headquarters, and also where they have hosted back offices for places where they had far smaller offices, which they visited a lot less frequently, such as Somalia).
When in Kenya, on business, I often took an additional day or two of leave, and visited national parks (the wildlife is stunning), as well as tea and coffee plantations (and Kenya produces excellent tea and coffee).
While visiting a coffee plantation, where I was given a tour, I was shown the coffee plants, and was allowed (and encouraged) to handle some coffee cherries/berries.
To my surprise, the coffee berries come - almost like an onion - with several layers, before one actually gets to the seed (what we then come to call the bean, and this is the green bean we are familiar with); however, unlike an onion, these different layers themselves differ from one another, and one of them is a kind of mucilage with a sort of slimy skin.
The 'washed' method involves removing the cherry - outer shell, and this mucilage and submerging the rest of the cherry in water which removes the remaining flesh surrounding the coffee seed (or berry, or bean). After the remaining flesh has been removed, these beans are then washed again.
This method is thought to lead to a "cleaner" - and sometimes, a more "complex" taste.
Naturally dried coffee, - which is an older, and more 'traditional' method, (and is especially useful in places where the water supplies might not be regular or reliable, or where drought may be a feature of the climate) by contrast, doesn't remove the respective 'layers' of the coffee cherry until after it has been dried.
In east Africa at least - this involves the coffee cherries being dried - separated individually - on raised beds so that the air can circulate entirely around the coffee cherries. Only then, are the seeds/berries removed from the rest of - or remainder of - the coffee cherry. However, as the cherry shell and mucilage are still part of the bean when it dries, this is thought to enhance the qualities of the bean and the flavour of the bean when it is finally extracted from its cherry shell.