I do a 'long' course when letting any one use my fountain pen. And put on my 'eagle' eye glasses to frown at them.
Now there is a great lie...memorize. "I can't let you use my fountain pen. It is very delicate. It took ages for it to work into fitting my Hand. Any use by others will ruin it for months."
It is a lie used by generations of fountain pen users.
You know know what a Ham Fisted Ball Point Barbarian can do in only two lines. You needed a nail nib... If it was a nail.... There is no hope for your ex friend. He'd bend a hammer.
I use the second strategy with everyone.
I have always carried backup pencils and ballpoints as well as extra filler paper.
I started to lend the writing instruments and give away filler paper since I was in 5th grade.
It was the year I got my first steel bodied Waterman and second fountain pen, using the first one, a plastic shiny dark brown Stypen with a stylish similar to the Sheaffer No Nonsense, I as given the year before, as a backup.
Nobody was allowed to borrow my fountain pens, and those who came to class empty ended were politely but firmly asked to give the borrowed pencils and ballpoints back.
Today, the same principle apply.
I always encourage new fountain pen users to avoid lending their instruments, because most people do not know how to use a fountain pen properly; and would, most probably, damage the nib, ruining a perfectly wonderful writing experience.
Some people have cheap loaner(s) fountain pen, that is a great idea!
Edited by Anne-Sophie, 09 February 2016 - 17:40.