Okay, but do I just disolve a Vitamin C suppliment in water, or what?
Basically, no, a Vitamin C supplement can contain anything else e.g. like Calcium, Vitamin D3, and/or lemon flavorings etc. For a real "1% w/v solution" you need a "pure" Vitamin C = ascorbic acid powder/ crystalline offer. Available at most drug stores. Of course, you can also just try out out any solution of any "Vitamin C supplement" in water, whatever the concentration. Restriction to "1%" is silly, you can use any concentration of ascorbic acid -- or the above-mentioned other alternatives -- you can imagine. Just leave the pen in it overnight and wash out enough the next day.