Can you reuse a cartridge?
You can reuse a 3ml cartridge, but you should not. The rubber plunger takes a set after the first pass and seals less reliably second time round, and you cannot re-sterilise glass properly at home. At about a pound each, reuse is a false economy.
What actually degrades
Two things. The rubber plunger is compressed against the glass wall for the whole time it is in use and does not fully recover its shape, so the seal on a second run is looser. And the crimped aluminium neck at the business end is designed to be pierced, not re-pierced repeatedly.
Neither failure is dramatic. What you get is a cartridge that weeps slightly at the stopper when the pen is dialled, which shows up as a damp barrel and doses that are quietly short.
The sterility problem
New cartridges are steam sterilised at the factory and sealed individually. At home you have rinsing and alcohol, neither of which sterilises anything. You can clean a cartridge. You cannot sterilise one.
If you are going to reuse one anyway, at least keep it to the same contents, rinse it immediately after emptying rather than letting residue dry, and stop after the second use.
The arithmetic against it
Check the current cartridge price on the product page.
Questions
- Can I put a cartridge in a dishwasher or autoclave?
- No. The heat deforms the rubber plunger and can weaken the crimped neck. You would be left with a clean cartridge that leaks.
- How many times can one realistically be reused?
- People report two or three. The seal gets worse each time and the failure is gradual, so you tend not to notice until doses have been short for a while.
3ml Glass Cartridge
One 3ml refill cartridge.