Case study
Anatomy of a problem we didn't solve first time
The brief was simple. Getting there took months, several dead ends,
and one complete change of direction.
The brief
A licence that cannot be removed intact - and announces any attempt
Simple to state. It contains a contradiction.
The same item has to survive twelve months on a vehicle, in all weather, and then come off by hand at renewal - quickly and cleanly, in a busy test centre with a queue outside. Make it secure enough and you make it immovable. Make it removable and you make it stealable.
What follows is how we got from one to the other.
What we tried, and threw away
Three approaches that did not survive
Abandoned
Edge-lifting tools
They failed, but produced the principle that has shaped everything since: the adhesive has to come away in contact with the product itself, as one piece - not separately, and not in fragments.
Abandoned
Heat
Hair dryers, heat pads applied directly. It works beautifully on a bench and is useless with twelve vehicles waiting.
Abandoned
Grip tabs, then a third layer
Tabs folded beneath a third layer. That one worked. We abandoned it anyway - too many parts, too many assembly steps, too much to go wrong in production.
The thing we had wrong
We had been solving the wrong problem
We were treating removal as the difficulty. It was not. The difficulty was that a product removed cleanly was a product that could go somewhere else - onto a vehicle with no right to it. Every improvement we made to removal was quietly making that worse.
So we stopped trying to make removal tidy, and designed the product to destroy itself instead.
Where it landed
Two thumbs, and it is useless
The product in service now is straightforward, which is usually the sign that the hard part is over.
A perforation runs the full centreline of both layers. A small, precisely shaped area of the window-facing adhesive is chemically killed at the edge, giving an operative two thumbs' worth of purchase and nothing else. The rest is bonded at full strength.
Two thumbs into the gap, pull apart, and it splits along the weak line. It comes off in seconds and it is useless the moment it does.
Along the way
Four things nobody briefed
- Independent UV testing at an ISO/IEC 17025 accredited test centre, to confirm the materials would survive the term.
- Microbiological testing, because mould had been reported in a handful of vehicles. Nobody asked us to look at that. We designed it out of the geometry rather than treating it afterwards.
- A manufacturing constraint found late, which ruled out an entire family of designs we had been developing.
- Repeated demonstrations at the authority's own premises, watching the people who would be doing this every day, and changing the design after each one.
And we are still at it
We don't consider any product finished
The current design works and is in service. We are presently testing variations on one detail - the precise shape of that unbonded area - because we think there is a little more in it: an easier first lift, or the same result for less adhesive given away.
None of this was briefed. Nobody asked for a weak point, or for the mould to be designed out, or for a family of designs to be abandoned before a single sample was made. It came from looking at the problem for long enough to find out what it actually was.
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