Thank you for the effort you are going to in order to do the right thing. I want to second my fellow members and suggest you give it to your sister. That pen will be easy to flush. It has a screw on cap which you remove just as if you were going to write with the pen. Then, holding the section (the bit just above the nib - the end that touches the paper), unscrew the barrel of the pen. You should be left holding the section with the nib pointing one way and the guts of the pen pointing the other. Now, the guts of the pen on this pen are either a cartridge or twist filler.
If it is a cartridge, remove the cartridge (save it for reference as what to buy to replace it). Put the nib and section end in a small glass of cool water and allow it to soak over night. Then, rinse the nib and section end in a small stream of cool water and put it back into the glass with clean, cool water and allow it to soak until the water remains clear (changing the water as needed). Now hold the nib and section end in a small stream of cool water with the water entering the section end and running down out of the nib end until the water runs clear. Warning #1: the sink or basin may be stained by the water/ink mixture that comes from the nib and section end of the pen. Warning #2: this process may take quite some time. Once the water flushing through the section and nib end runs clear, dry the nib over night by placing a wad of paper towel in a small glass and placing the section and nib end in the glass with the nib pointing down and in contact with the paper towel. Once the nib and section end are dry, replace the cartridge with the correct size cartridge full of your sister's favorite color of ink, replace the body of the pen by screwing it back onto the back of the section end, and replace the cap by screwing it back over the nib end.
If, on the other hand, it is a twist filler, first check to see if there is any visible ink in twist filler. If there is (unlikely, but possible), hold the pen nib end down over a sink or drain and twist the filler stem in such fashion as to expel the ink which I believe is twisting the stem to the left. With the twist filler empty, half fill a small glass with cool, clear water. Place the nib end of the pen well into the water and twist the filler stem in the opposite direction (I believe this to be to the right) to draw water into the twist filler. Now, with the twist filler full or nearly full of water, place the nib all the way down in the glass and allow it to soak over night. After soaking, expel the water from the twist filler through the nib into a sink or drain. Replace the water in the glass with cool, clear water and refill the twist filler with water and place the nib down in the glass and continue to soak the pen. Continue this procedure until all there is no trace of ink in the glass. Again repeat the process of expelling the water from the twist filler through the nib and then, holding the section of the pen, place the nib pointing down in a small stream of cool, clear water until the water runs clear. Warning #1: the sink or basin may be stained by the water/ink mixture that comes from the nib and section end of the pen. Warning #2: this process may take quite some time. Once the water flushing the nib end runs clear, dry the nib over night by placing a wad of paper towel in a small glass and placing the pen in the glass with the nib pointing down and in contact with the paper towel. Once dry, refill the twist filler with your sister's favorite color of ink, replace the body of the pen by screwing it back onto the back of the section end, and replace the cap by screwing it back over the nib end.
That is all there is to it. If it fails to write effortlessly and wonderfully, let us know. We will walk you through the minor repairs that may be needed.
Warning: If you sister objects to weight of the pen, you may have just found and flushed a fountain pen for yourself. That could lead you back to us. Both you and your sister are more than welcome here.
-David (Estie).
