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I lack the expertise to comment on the sensitivity of the cellulose specifically, but the metro stations where I live will perform random stops as you enter, an

by csydas 9y ago

I lack the expertise to comment on the sensitivity of the cellulose specifically, but the metro stations where I live will perform random stops as you enter, and the monitors are in plain sight. Notebooks, stacks of paper, and note cards are usually pretty clearly detected by whatever software they're using to help highlight items. It seems weird to me that there could be such difficulty with TSA scanners versus the small, older ones set up at stations here. (St. Petersburg, Russia, just for reference for the location)

learc83 9y ago
>Notebooks, stacks of paper, and note cards are usually pretty clearly detected by whatever software they're using to help highlight items How do you know the problem isn't that the software flags dangerous items as paper incorrectly (which I think is the mostly likely problem here)? I doubt you've seen the X-ray image of someone smuggling nitrocellulose. The software is just using density--if you have an explosive of similar density to paper, it's probably not going to flag it.
- csydas 9y ago
  Well, I was more specifically replying to the comment "It is the cellulose in the paper. Blocks of it are homogenous enough that they look similar in density to something dangerous." Every time I've seen it on the scanners here, or the glimpses I've seen at airports last I was in the US, usually it's very clear what you're looking at - books and other paper products are plain to see. If they obfuscate, sure, possibly. But just from personal experience it doesn't seem like it would be indistinguishable. I'm not saying that these tools are infallible by any means, just that the particular claim didn't mesh with my experience.
  - learc83 9y ago
    An x-ray only shows density. 2 equally dense objects will look the same regardless of chemical composition. What you're likely seeing is computer enhanced images, which may be giving you a false sense of the capabilities of x-rays. There are explosives with densities fairly similar to paper. A block of those explosives, and a block of paper would look very similar on an x-ray.

by csydas 9y ago

learc83 9y ago

>Notebooks, stacks of paper, and note cards are usually pretty clearly detected by whatever software they're using to help highlight items How do you know the problem isn't that the software flags dangerous items as paper incorrectly (which I think is the mostly likely problem here)? I doubt you've seen the X-ray image of someone smuggling nitrocellulose. The software is just using density--if you have an explosive of similar density to paper, it's probably not going to flag it.

csydas 9y ago
Well, I was more specifically replying to the comment "It is the cellulose in the paper. Blocks of it are homogenous enough that they look similar in density to something dangerous." Every time I've seen it on the scanners here, or the glimpses I've seen at airports last I was in the US, usually it's very clear what you're looking at - books and other paper products are plain to see. If they obfuscate, sure, possibly. But just from personal experience it doesn't seem like it would be indistinguishable. I'm not saying that these tools are infallible by any means, just that the particular claim didn't mesh with my experience.
- learc83 9y ago
  An x-ray only shows density. 2 equally dense objects will look the same regardless of chemical composition. What you're likely seeing is computer enhanced images, which may be giving you a false sense of the capabilities of x-rays. There are explosives with densities fairly similar to paper. A block of those explosives, and a block of paper would look very similar on an x-ray.