Manu Propria's Genious Eye-Dropper Soultion


There is a phenomenon with eye-dropper pens that nobody can really explain, the phenomenon of "spontaneous discharge" of the ink through the feed.
In the internet I have found quite a number of patents that try to deal with this problem, among them one of Namiki.

The only thing most agree on is, that the phenomenon appears when the ink in the tank reaches a critical volume of around 30%.

I was reflecting on this problem a while because I offer the "Suisô" eye-dropper with a volume of over 10 ml. A spontaneous discharge in this case would create quite a mess.

I made some experiments with filling the barrel with sponges, cotton and silk floss.
My idea was to prevent of hollow cavity and a quick air flow in the tank. Finally I came to the conclusion that cotton is the perfect medium.

The barrel is tightly filled with medical cotton wool.
Interesting also, that the ink capacity in the tank is not significantly effected or reduced by the cotton.

The first ink filling takes quite a while until the cotton is completely saturated, refills go quickly.