I've filled my TWSBI 580 Diamond with KWZ Ink IG Blue Black in April 2016, and refilled it six times without flushing (despite warnings on KWZ Ink webpage). In February 2017 my pen looked like that:
Along piston operating range barrel was clean, but below there was dark residue.
I've asked Mrs KWZI for some hints on cleaning my pen.
She adviced me to crush three pills of Vitamin C (in Poland Vitamin C is sold as 200mg pills), dissolve them in 30ml of water, and load this solution to my pen and keep it there for a few minutes, and repeat this procedure until residue is dissolved.
I had no Vitamin C at home, so I used the following procedure:
- I've measured 1g of citric acid (white pellets).
- I've added ~50ml of demineralized water (tap water is very hard at my place, it is the same demineralized water I use to fill steam iron).
- I've heated it to 35° Celsius (to make it easier to dissolve citric acid, this step is not strictly necessary, but I had baby bottle heater available)
- I've stirred it (or rather shaken, as my container had a lid).
- I've filled my pen with solution, waited 5-10 minutes, gave it good shake and emptied it.
- I've repeated step 5 until residue was dissolved (three more time).
- I've flushed the pen with demineralized water twice.
Later I was told that:
- ascorbic acid (Vitamin C) is more effective than citric acid.
- citric acid works better if one adds a little of baking soda.
Edited by ksm, 22 February 2017 - 12:56.