Difference between spill and soak resistance

Some inks are marketed as "water resistant" while others are "permanent". Most inks have little to no resistance to water, and that is fine for most of us. However, when you are writing something that needs to be presentable even if someone drips water on it, then you need a water resistant ink. For example, in an office environment, we frequently make notes on papers for colleagues who then carry the paper around. Sometimes, they drip coffee or water on the page. If ink is not resistant to that spill, they may end up with a blurred, illegible note from you. You need water resistance in cases like this.

There is a difference between water resistant and permanent. Permanent means the ink will be there, clearly unaffected by water. Water resistant means that enough of the ink remains to provide a legible text even though some or most of the color has washed away. Depending on how the water resistance is implemented, the washed away color may stain the paper or it may completely wash off.

Here is an example of a water resistant ink that washes off some green color, staining the paper, but leaving behind a permanent, legible text that will remain even after the paper is destroyed. If you can live with some staining and color wash, inks like these are far more prevalent than fully permanent inks, giving you many more color and property choices.

Noodler's Zhivago is an interesting water resistant ink. It's base color is a permanent black. The black is augmented with a hint of a green color giving the ink a mysterious appearance depending on the paper type and wetness of the nib. A drier nib reveals more of the greenish tint while a wet nib looks very black.

The water resistance of this ink is shown in the two scans. The first scan is a simple spill test. Paper is recycled 20 lb. copier stock. Tap water was poured over the page and let drip, then placed on a paper towel to dry. Note the bleeding of the green onto the white paper. The black base color is unmoved.

The next sample is the same page after a three hour soak in tap water. Note how the green has either washed away completely, or diffused across the entire page adding an overall green tint. The black base color is clearly permanent and unmoved.

The conclusion is that a semi-permanent so-called water-resistant ink like Noodler's Zhivago, works very well in an office or professional environment. It would also be useful for journaling where you want to ensure your words are preserved, but 100% permanence is not needed. This gives you more flexibility in color and property selection.