Attunement is a measurement of compatibility between a drucrafter and a sigl. Higher attunement means a sigl will function better, lower attunement means a sigl will function worse, and below a certain minimum a sigl will not function at all.
Attunement can be measured either as a percentage (between 0% and 100%) or as a ratio (1 to 1, 3 to 1, etc). These are just different ways of expressing the same thing; 1 to 1 means 50%, 3 to 1 means 75%, and so on. In both cases, what they’re measuring is what fraction of the sigl’s kernel is made up out of the drucrafter’s personal essentia, and what fraction is made from a different type of essentia (or from nothing at all).
Attunement matters because a sigl’s kernel being made from a drucrafter’s personal essentia is what makes it their sigl, and not someone else’s. If that fraction of personal essentia drops below a certain level, the sigl won’t work. The exact point at which that level is crossed is variable and depends on multiple factors, but on average tends to fall somewhere between 20% and 25%.
For shapers who make their own sigls, attunement is usually irrelevant. Since they’re the one and only person shaping the sigl, it of course will contain no personal essentia except their own. As such, it’s easy for a shaper to forget just how big a problem attunement can be for everybody else.
Sharing the Load
Most sigls in the modern day are commercially produced and sold for profit, rather than being used by the shaper who creates them. This causes an inherent tension in the shaping process. To create a sigl, a shaper must use their own personal essentia to do so (otherwise, they’d have no way to shape the sigl in the first place) and from the shaper’s point of view, the more of their own essentia that they use, the easier the sigl is to shape. However, from the point of view of the end user, the ideal is for the sigl to contain as much as possible of their personal essentia, and as little as possible of the shaper’s. The higher the ratio of the user’s personal essentia to the shaper’s, the more effective the sigl is going to be.
The compromise that most manufacturers have settled upon (at least in the Western world) is a ratio of 3:1, or 75%. Most reputable sigl providers will guarantee this as a minimum (which means in practice that most manufacturers will try to go as low to this number as possible without quite dipping below it). Higher-end sigls aimed at the luxury or professional markets may advertise attunement ratios of 4:1 or occasionally even 5:1, though a ratio of 5:1 is considered extremely difficult for a shaper to achieve (and in practice most channellers can’t tell the difference between a 4:1 and a 5:1 sigl anyway).
However, even a sigl with a low attunement ratio results in a finished product which is more than usable . . . as long as it’s a solid sigl. The real problems start when it isn’t.
Engineered Weakness
One of the more dubious legacies of 20th-century drucraft was the technique of producing ‘threaded’ sigls. Essentially, threading is a method of reducing the essentia content of a sigl by removing non-essential parts. This allows for much cheaper sigl production, but at the cost of drastically reduced attunement and lifespan . . . and these reductions are cumulative.
Put all this together, and one can end up with a sigl produced at a 3 to 1 attunement ratio (75%), that is also heavily threaded (reducing the sigl’s effective attunement by half) and which (due to said heavy threading) sublimates orders of magnitude faster than a solid one would. Such a sigl could be bought new and yet still end up hovering between 20% and 30% attunement after only a couple of years. This is how one gets the notorious ‘junk sigls’ flooding modern markets, which despite technically having a 3 to 1 attunement ratio, have lifespans of two to three years at most. For those unfortunate enough to have to rely on such sigls, attunement is less a measure of compatibility and more of a ticking clock that measures how long they have before the sigl will have to be replaced.
