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To understand how duct tape is engineered, Bill dissolves the tape in solvent to reveals its three components — plastic backing, adhesive, and cloth reinforcement. He explains the function of each part, highlighting that the adhesive is a viscoelastic substance — a substance that can act like a liquid or a solid and it can behave elastically. It is these behaviors underlying the characteristic behavior of duct tape: adhere when light pressure is applied, hold tight, then let go when peeled from a surface.
*Video summary*
00:00 Titles/Introduction
Bill explains that duct tape was invented in the 1940s to seal ammunition boxes, but now is used to temporarily fix many things.
00:21 Duct tape on Apollo 13
Bill notes that duct tape was used to repair a carbon dioxide filter on the Apollo 13 Moon mission in 1970. The improved filter was needed because an explosion destroyed part of the life support system.
00:35 The basic functions of tape
Tape is designed to do three things: a) adhere with light pressure, b) stay in place, yet c) be removable.
00:53 Components of duct tape
By dissolving duct tape in the solvent toluene, Bill separates duct tape into its three components: plastic backing, adhesive, and cloth reinforcement.
01:32 Properties of Tape Adhesive
Bill contrasts the adhesives used in tape with glue to highlight the unique properties needed for tape adhesive. He shows that Elmer’s glue, a typical household adhesive, dries by evaporating solvent until it becomes solid. He notes that this would _not_ work for duct tape. Instead, tape’s adhesive never hardens because it must adhere when pressure is applied (rather than dry to adhere like Elmer’s glue), hold tight, then let go when the tape is peeled from a surface.
02:11 Tackifier
Bill explains that the stickiness of duct tape comes from a substance called a tackifier, which is a substance that is sticky like syrup. He demonstrates that a tackifier alone isn’t enough for tape: a tackifier can affix something lightweight, but fails with heavy loads. This is unlike duct tape, which can hold at least a 5 pound/2.3 kilogram weight.
02:46 Viscoelasticity
Bill notes that the adhesive for tape is a tackifier mixed with a viscoelastic substance. A viscoelastic substance is a substance that can be, depending on the rate at which it is deformed, liquid-like, solid-like, and which can exhibit elastic behavior. He demonstrates this with a familiar viscoelastic substance: Silly Putty. He shows Silly Putty flowing, fracturing, and bouncing — that is, behaving like a liquid, a solid, and exhibiting elastic behavior.
03:46 Close up of tape being applied
A close up of a piece of tape being applied to a glass surface illustrates how tape’s adhesive displays liquid-like and solid-like behavior. When applied it behaves like a liquid: light pressure causes the adhesive to flow and “wets” (i.e., spreads over) the surface, which allows it to stick to a surface. Once applies the adhesive behaves like a solid to support weight and keep the tape in place.
04:13 Cloth reinforcement
Bill mentions that the weight is held up by the cloth reinforcement. He examines close up the cloth reinforcement used in tape.
04:51 Close up of tape peeling
Bill shows that when tape peels off a surface it exhibits elastic behavior, although sometimes some of the tape’s adhesive can stick to the surface. This is cohesive failure. When this happens the adhesive is behaving like a solid.
06:22 Why gaffer’s tape doesn’t leave residue
Bill explains how gaffers tape and sticky notes peel off a surface without leaving residue.
07:07 Release coating
Bill describes the silicone-based release coating on tape’s plastic backing, which allows it to be formed into a useful roll. This adjusts how much tape sticks to itself. If it sticks too tightly, a user could not remove the tape from the roll; if too loose, then the tape would telescope — he demonstrates the latter with a defective roll of tape.
08:37 Tape adhesive developed by the engineering method
Bill explain briefly that while chemistry is important to synthesize the adhesives, their development is done by the engineering method. The engineering method is described in his book _The Things We Make_ (isbn 978-1728215754 hardcover / 978-1728280455 paper).
09:36 Rolling ball test
Bill demonstrates the rolling ball test to quantify the stickiness of a tape’s adhesive. This is one of many empirical methods used by engineers to engineer tape.
10:15 Where duct tape should not be used
Bill ends this video with a caution: Duct tape — surprisingly! — should never be used on ducts.
10:33 End Credits
ALTA recent New Scientist cartoon.
The first real money I ever made from game development was on Android. It was in 2013, when Android was still the underdog compared to the iPhone, and was being touted as a great platform for developers. I’d taken two weeks to build Patchy, a retro arcade game revamped for touch controls, and published it on the Google Play Store without any hassle. Since then, I’ve also published Twistago, Rocket Mail, Bigcanvas, Radio Nul and Papageno.
With each next app, the bar for publishing kept getting higher. At some point, Google started publishing developers’ full company address on the store alongside the app. That’s fine for a professional company, but quite problematic for a solo indie developer who works from home, especially if the app or the developer is even remotely controversial. I worked around it at the time by just putting the name of the town instead of the full address, which is only right morally, but not legally.
The technical requirements also kept going up. To publish an update to an app, it has to target the latest API version, which goes up once or twice a year. Each API update comes with a slew of deprecations, and breaking changes to the already inscrutable build system. And even if you don’t want to update the app, Google will eventually start hiding apps from users if the app doesn’t target some minimum API version. This means you can’t just publish an app and leave it at that; it’s several days of work per app per year to keep up with the latest rug-pulls from Google. Again this is no problem for a company for whom the app is their core business, but bad news for indie and hobbyist developers who just want to make something cool, put it out there, and move on to the next project.
And then, there’s the latest increase in publishing requirements, the straw that broke the camel’s back, which made me decide to abandon the Google Play Store altogether.
The new rules
The original announcement just mentioned that organizations will need to provide a D-U-N-S number. It was possible to choose your own deadline, so I set it as far in the future as I could. Now that deadline, 5 November, is getting close, and I can start the verification process. The email, however, makes it clear that they want much more than a D-U-N-S number:
What you need to provide to verify
- a D-U-N-S number for your organization
If you don’t have a D-U-N-S number, request one at no cost from Dun & Bradstreet now. This process can take up to 30 days, so we recommend requesting a D-U-N-S number immediately. Learn more about requesting a D-U-N-S number- a phone number and email address for Google Play users to contact you
- a phone number and email address for Google to contact you
- an official document to verify your identity
- an official document to verify your organization
There is only one of these items that I don’t have a problem with.
The D-U-N-S number is only needed if your Play Store publisher account is for an organization, not an individual. But I’m registered as a sole proprietor, so the rule applies to me. You can look up your company’s D-U-N-S number, but the form doesn’t (currently?) allow selecting any country except the US. Dun & Bradstreet’s partner in the Netherlands, Altares, does allow me to look up my own company, but charges 15 € for the privilege of seeing my own data, including my own D-U-N-S number, which they’ve apparently already assigned when I registered with the Chamber of Commerce. If I didn’t already have one, I don’t see a way on their website to request one either, even though the FAQ mentions that you can (for a fee, of course).
While that may be just some paperwork and a small expense, the next requirement is more insidious: “a phone number and email address for Google Play users to contact you”. I’m fine showing an email address, but I absolutely do not want my phone number to be available to anyone on the internet. (Even for phone calls. But remember that a phone number is used for much more than phone calls these days.) And that’s just me, a privileged hetero white cis dude who is unlikely to be the target of harassment or doxxing.
The requirement “a phone number and email address for Google to contact you” is the only one that sounds benign to me, although I have yet to see Google trying to contact small-fry developers like me by phone, instead of just reaching for the algorithmic ban hammer if I cross any line.
An “official document to verify your identity” would presumably be a scan or photo of my passport. Now, I have reasonable confidence in the security of Google’s systems, but this is something very sensitive and can easily be abused if it fell into the wrong hands. And why is it necessary? I’ve done business with many other companies, where a lot more money was changing hands than I’m getting from my Play Store apps, but they never asked for my passport. Why does Google?
Those other companies also never asked for “an official document to verify your organization”. Presumably this is a document I can request from the Chamber of Commerce to the tune of another 9 €, but again I’ve never had another company ask for this when doing business with them.
In conclusion
I sort of understand why Google is doing all this. It’s partly legal requirements (especially EU), partly an attempt to reduce spam and malicious stuff. Some of it might even be in the best interest of the end user.
Larger companies have the resources to deal with all this, and for personal accounts the rules are much more lenient. Sadly, there has been little consideration for sole proprietorships like mine, which fall somewhere in between: bound by the same rules as big companies, but without the means to play by them.
And this is why I’m just going to let my Play Store developer account expire. Starting on 5 November, you won’t be able to install any of my apps anymore. Most of them were not actively maintained anymore, but they still worked, because the Android operating system itself is actually pretty good at backwards compatibility.
Even though there was little remaining interest in my older apps, it makes me sad that people won’t be able to use them anymore. The one I’m most sad about, though, is Papageno, an unfinished side project about bird sounds that I haven’t worked on for three years, but keeps popping into my mind as something I’d really like to finish some day. Maybe it could be in the form of a web app. We’ll see.
Also I've successfully promoted the latter with friends and family on multiple occasions, so it's definitely worth pursuing
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Who's a morally relativist boy? It's you!
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