How smart is SmartWater?

January 28, 2008 4:26 AM

How does SmartWater "forensic property coding" work?

Specifically:

1. What is the underlying "DNA-style chemical" technology used to make and extract the code?

2. Why is it more effective than marking an item in indelible UV ink?

3. Has it ever been used to make a criminal conviction, or is it only effective as a deterrent?

posted by roofus to science & nature (5 comments total)

this patent, which may be the "smart water" patent, describes several classes of chemical that might be used. However, I don't see anything "dna-like" in that patent--most likely, calling it a "DNA-style chemical" is more marketing than scientific.

Basically, the patent seems to describe a system where a combination of individually detectable substances are combined into the spray. Each substance is given a value, and the number encoded by the substance is the sum of the individual values.

Here's a toy example: Let "sugar" have the value 1, "salt" have the value 2, "lemon juice" have the value 4, and "cayenne" is 8. After water with trace amounts of one or more of these additives has been sprayed on a surface, just give it a lick. If you taste "lemon juice" and "cayenne", then you've tasted substance number 4+8=12. In this example, there are 15 substance numbers (plus 0 for plain water).

In that patent, there are simply a larger number of additive substances, such that there are billions of combinations.
posted by jepler at 5:54 AM on January 28

Here's the U.S. patent. They don't appear to specify DNA, but it is possible to use DNA as a taggant.
posted by grouse at 6:45 AM on January 28

Here in Puget Sound country we've had a lot of trouble with small to medium sized oil spills, mainly heavy bunker oil for fuel, which cannot definitively be traced to a specific vessel. I've often wondered if some substance could be added in trace amounts to fuel tanks (and other tanks)-- it would have to be mandated by federal law, of course-- that could allow blame to be unequivocally assigned in these cases.
posted by jamjam at 11:02 AM on January 28

>Why is it more effective than marking an item in indelible UV ink?

Surely the answer to that is: because criminals know about indelible UV ink, and have the means to get rid of it.
posted by AmbroseChapel at 4:57 PM on January 28

This sounds sort of like snake-oil. Putting the VIN number on auto parts certainly didn't stop crime, and this won't either.
posted by gjc at 6:04 PM on January 28