Thank you! I figured not every potion would be a literal glass bottle of syrup. Glass is EXPENSIVE, everyone! Though, come to think of it...
Oil of Glass Fingertips
Rego Aquam 13 (base 1, R: Touch, D: Sun, T: Part, +1 slightly unnatural control, +3 for Penetration 6) charged item
Despite the name, this green glass bottle contains doses of a thick, gritty ointment of ground clam shells which barely resembles oil at all. Rather, it is named for its effect; rubbing this ointment on a person or object causes liquids to bead and slide off like rain on a seabird's back until the next sunrise or sunset. Acids and other malign liquids only cause damage on the first round of contact or partial immersion, with full immersion regrettably breaking the ointment's effect. The Oil of Glass Fingertips does not prevent the user from drinking water unless it is ingested orally, a foul idea unlikely to happen by accident. The lab text for this item provides a bonus of +2 from the clam shell's protection sympathy; copies of this text are spread across the north shore of the Mediterranean and are simple to find.
In an unsurprising case of divergent evolution, nearly identical versions of this potion were developed in both Rome and Athens before either city's tribunal had begun sharing correspondence with each other. In the Theban Tribunal, it is easy to spot a Hermetic apprentice because they are perpetually covered in lumpy gray paste. The slight penetration also allows said apprentices to fetch pharmaceuticals from the local village without accidental self-poisoning.
Oil of Rain Dancing
Rego Auram 15 (base 4, R: Touch, D: Sun, T: Individual) charged item
A waterskin made from a sealed sheep's stomach, filled with the oil from pressed acorns. When the oil is rubbed onto a person's forehead, falling rain cannot touch them until the next sunset or sunrise. Wind may still chill and lightning may still threaten, but clothes and hair remain dry. The lab text for the Oil of Rain Dancing provides a +3 bonus; oak's protection from storms is far stronger than that, but the thoroughly researched version of this text tends to be buried far back in any given covenant's library.
Apprentices who are regularly sent to harvest vis in the wilderness will eventually cook up a similar potion if they have any sense of self-preservation. Those living too far south to find oak trees are stuck with the Oil of Glass Fingertips instead, much to their chagrin. Covenants producing this potion tend to leave behind astounding amounts of dry acorn mash, which either attracts birds or makes the grogs angry at the dinner table.