Mizuuchiwa(Water Fan) distinguishes itself in its unique translucent appearance. One cannot believe that it is actually a washi(Japanese handmade paper) product.
Its main feature is extremely thin Gampi washi, which is pasted on bamboo frame and coated with natural varnish. The varnish finish brings out its translucent beauty, and gives you refreshing coolness.
There are several views about the origin of the name, Mizuuchiwa(Water Fan). One explains that the word Mizu(water) comes from the way the fan was used in old times when there was no air conditioning-the paddle was dipped in water to fan cool air, using evaporation heat. Another says it comes from its resemblance to clear water. In any case, its birthplace, Gifu, is known for Nagara River, which has been the cradle of river culture, giving birth to Mino washi, and "Ukai"（cormorant fishing, a traditional method of river fishing).

The paper used for Mizuchiwa is called Gampi washi, and it is manufactured by "Corsoyard", a group of local washi craftsmen. Gampi washi is one type of authentic Mino washi, a local specialty.
The raw material for Gampi washi is the inner bark of Gampi tree. Gampi fibers are thinner and finer than those of Kozo(paper mulberry), a more popular material for washi. A Gampi product is therefore durable, smooth, and pellucid.
The initial preparation of the raw materials takes a lot of time and effort. In order to produce spotless paper, all the impurities and dust must be removed. In general paper production, any unwanted spots are bleached to save time, but Corsoyard craftsmen never resort to such artificial manipulation. Instead, they spend a long time picking up any extraneous matters in the Gampi fibers soaked in cold water.
The outstanding translucent beauty of Mizuuchiwa is undoubtedly the fruit of such painstaking preparation.

By dipping Mizuuchiwa in water, you can enjoy a splash while fanning yourself, which is a playful and elegant way to cool off. It is partly for this purpose that Mizuuchiwa is coated with special varnish.
This particular varnish enhances the unique translucency and water resistance of the fan.  It is made from all natural ingredients, although petroleum-based varnish using chemically modified organic solvent may be more common in general. 
The same varnish is applied for violins or even chocolate candies.  So you can see it is quite safe. 
(Even though the fan is water-resistant, leaving it in water for many hours may damage the coating and cause cloudiness.)