Can I use this inkstick together with other brands or with liquid ink?

Please check the glue ingredients before mixing inks from different sources — inks using a compatible type of natural animal glue can generally be mixed without issue, but combining different glue bases (for example, natural glue with synthetic glue) can cause separation or an uneven texture.

When in doubt, test a small amount first.

Also note that once ink is ground, it doesn't stay in ideal condition for long — it's best to grind only as much as you'll use that day, rather than storing mixed ink for later.