Retractable writing tool and self sealing valve

A retractable writing tool comprising:

• a rear barrel (202) and a front barrel (207) having an opening (203) and a tip (101) capable of moving between a retracted position and a protracted position;
• a feeder (107) capable of conveying fluid to the tip (101) and a valve (206) having a front end (103) and a back end (104), where the front end (103) has a round face with a concave shape profile at the point where the tip is to exit and a slit (600), the front end (103) is adjacent to the opening (203) of the front barrel (207) so that in the retracted position the tip (101) is between the front end (103) and the back end (104) substantially sealed from outside air to substantially prevent the writing fluid from evaporating to the outside air, and preventing the release of vapor fluid from within the enclosure (102) when the tip (101) is in a retracted position, where in the protracted position, the tip (101) extends through the slit (600) of the valve (206) and opening (203) of the front barrel (207), where the valve (206) is made of silicone.