Last night one of my players was lamenting (well okay: Whining and complaining) about how scroll scribing works in my campaign. His complaint "why are ink formulas different for each character, the spells are the same, the spell components are the same? How does anyone learn alchemy if it's all different for everyone?"
Magic isn't science. Step A, step B and Step C do not create the same results for everyone all the time, ever notice spell effects vary by level and are often resolved by dice?
Alchemy is influenced by astrology; what sign you are born under influences the flow of energies that mortals recognize as magic. It isn't as simple as simple as what sign one is born under but also the alignments ans states of the moons, the positions of the planets, and the presence of comets at certain stage while the would-be spell-scribe is developing that go one to influence what components can be mixed together for any individual scribe to be mixed into an ink on a scroll they scribe. It's a very personal affair the inks that goes into a scroll duplicates some of the flows of energy that go through a caster's body and spirit when they cast a spell. So the influences that go into determining what inks will function and as such require each scribe to personally manufacture the ink for a scroll are: Their parents, the place of birth (within dozens of yards), the time of birth (down to the minute), the birth sign a character is born under, the alignments and states of the moons, the positions and alignments of the planets, the presence comets during the characters entire life up until the point a spell is learned, ethereal and astral weather, the influence of spirits and gods and some elements not identified all go into why they ink formula for each spell varies for each spell scribe.
The art (and skill) of alchemy isn't learning the specific formulas in and of itself but learning how to discover the formulas. I can paint a daisy, another artist can paint a daisy: the paint and brushstrokes used will not be identical a good artist learns the craft required to paint a rendition of a daisy not the exact process required to make the same daisy as everyone else.
Magic is not science, or at least magic is not a science the mortal mind fully understands. Magic is more accurately described as an art of multitudinous influences that the artist does not even recognize in the entirety of elements that go into each casting or scribing of a spell.
Luckily for my sanity as DM and for the players the immense mountain of
data and influences on individual characters discovering what formula works for a specific scribe is resolved by a few d12 rolls
to reflect a wide range of influences. There are only 144 possible
mixtures of ingredients for an ink for a 1st level spell and
26,623,333,280,885,243,904 for ink required for a 9th level spell. All
pretty modest and simple really compared to the vast range of influences
on magic. Dice are a wonderful tool to simulate the mostly unknowable.
Magic isn't science.
foot note: spell components are consistent for two reasons :no 2 characters are ever likely to know all of the 200+ odd spells in the campaign. There are power components which extend the capabilities of some spells, for some casters.