Never refill a Copic with regular isopropyl alcohol unless you have absolutely no other option.
Copic markers have their own ink refills to go with each marker,
They look like this and cost around the same price as a Copic Sketch maybe slightly more however they can be used to refill a marker several times
By using isopropyl alcohol what youâre doing, in fact, is diluting what little ink you have left in your make, therefore changing the shade of it.
Of course the one exception to this rule is the colourless blender 0 which is a marker that is full of regular isopropyl alcohol.
As a side note, DONâT throw away your marker if one/both of the is damaged
Copic also make replacement nibs for all of their markers
Which are much cheaper than buying a new marker as you get multiple in a pack.