How to Preserve Colored Inks.
If it is necessary to keep colored inks, the best way of preserving them so that they shall be workable after standing some time is to pour a little colza oil on the top, and securely close the vessel containing them. This oil will not generally rob the ink of any of its color, and even if it is not all poured off afterwards, its presence can do a piece of cotton wool; when dry, it may be washed in the same way as bronze. Rolling afterward will improve it very much.