When it comes to renewable energy, there are many great sources. Whether it’s solar, wind, or something else, though, we need a lot of it. Factories around the globe are rising to the challenge to provide what we need.
We can build plenty of new solar panels, of course, but we need to think about what happens when they reach end of life. As it turns out, with so much solar now out in the field, a major new recycling industry may be just around the corner.
Today, toothpaste tubes are mostly plastic, but they contain a layer of aluminum that helps it stay flattened and/or rolled up. So far, multi-layer packaging like this isn’t accepted for recycling at most places, at least as far as Australia and the US are concerned. In the US, Tom’s of Maine was making their tubes entirely out of aluminum for better access to recycling, but they have since stopped due to customer backlash.
Although Colgate’s new tubes are still multi-layered, they are 100% HDPE, which makes them recyclable. The new tubes are made up of different thicknesses and grades of HDPE so they can be easily squeezed and rolled up.
Toothpaste Before Tubes
Has toothpaste always come in tubes? No it has not. It also didn’t start life as a paste. Toothpaste has been around since 5000 BC when the Egyptians made tooth powders from the ashes of ox hooves and mixed them with myrrh and a few abrasives like powdered eggshells and pumice. We’re not sure what they kept it in — maybe handmade pottery with a lid, or a satchel made from an animal’s pelt or stomach.
The ancient Chinese used ginseng, salt, and added herbal mints for flavoring. The Greeks and Romans tried crushed bones, oyster shells, tree bark, and charcoal, which happens to be back in vogue. There is evidence from the late 1700s showing that people once brushed with burnt breadcrumbs.
Aside from its use in those pink gloopy solutions one takes for an upset stomach, bismuth has a lot of commercial applications. For the purposes of desoldering, though, its tendency to lower the melting point of tin and tin alloys like solder is what makes it a valuable addition to the toolkit. [Robin] starts with a demonstration of just how far a little bismuth depresses the melting point of tin solder — to about 135°. That allows plenty of time to work, and freeing leads from pads becomes a snap. He demonstrates this with some large QFP chips, which practically jump off the board. He also demonstrates a neat technique for cleaning the bismuth-tin mix off the leads, using a length of desoldering braid clamped at an angle to the vertical with some helping-hands clips. The braid wicks the bismuth-tin mix away from the leads along one side of the chip, while gravity pulls it down the braid to pool safely on the bench. Pretty slick.
Lest leaded solder fans fret, [Robin] ensures us this works well for lead-tin solder too. You won’t have to worry about breaking the bank, either; bismuth is pretty cheap and easily sourced. And as a bonus, it’s pretty non-toxic, at least as far as heavy metals go. But alas — it apparently doesn’t machine very well.
Scientists found a surprising amount of lead in a glacier. They were studying atmospheric pollution by sampling ice cores taken from Alpine glaciers. The surprising part is that they found more lead in strata from the late 13th century than they had in those deposited at the height of the Industrial Revolution. Surely mediaeval times were supposed to be more about knights in shining armour than dark satanic mills, what on earth was going on? Why was the lead industry in overdrive in an age when a wooden water wheel represented high technology?
The answer lies in the lead smelting methods used a thousand miles away from that glacier, and in the martyrdom of a mediaeval saint.
Everyone one of us is likely aware of what lead — as in the metal — is. Having a somewhat dull, metallic gray appearance, it occupies atomic number 82 in the periodic table and is among the most dense materials known to humankind. Lead’s low melting point and malleability even when at room temperature has made it a popular metal since humans first began to melt it out of ore in the Near East at around 7,000 BC in the Neolithic period.
Although lead’s toxicity to humans has been known since at least the 2nd century BC and was acknowledged as a public health hazard in the late 19th century, the use of lead skyrocketed in the first half of the 20th century. Lead saw use as a gasoline additive beginning in the 1920s, and the US didn’t abolish lead-based paint until 1978, nearly 70 years after France, Belgium and Austria banned it.
With the rise of consumer electronics, the use of lead-based solder became ever more a part of daily life during the second part of the 20th century, until an increase in regulations aimed at reducing lead in the environment. This came along with the World Health Organization’s fairly recent acknowledgment that there is truly no safe limit for lead in the human body.
In this article I’ll examine the question of why we are still using lead, and if we truly must, then how we can use this metal in the safest way possible.
For most of the history of industrial electronics, solder has been pretty boring. Mix some lead with a little tin, figure out how to wrap it around a thread of rosin, and that’s pretty much it. Sure, flux formulations changed a bit, the ratio of lead to tin was tweaked for certain applications, and sometimes manufacturers would add something exotic like a little silver. But solder was pretty mundane stuff.
Then in 2003, the dull gray world of solder got turned on its head when the European Union adopted a directive called Restriction of Hazardous Substances, or RoHS. We’ve all seen the little RoHS logos on electronics gear, and while the directive covers ten substances including mercury, cadmium, and hexavalent chromium, it has been most commonly associated with lead solder. RoHS, intended in part to reduce the toxicity of an electronic waste stream that amounts to something like 50 million tons a year worldwide, marked the end of the 60:40 alloy’s reign as the king of electrical connections, at least for any products intended for the European market, when it went into effect in 2006.
Did you ever stop to think how unlikely the discovery of soldering is? It’s hard to imagine what sequence of events led to it; after all, metals heated to just the right temperature while applying an alloy of lead and tin in the right proportions in the presence of a proper fluxing agent doesn’t seem like something that would happen by accident.
Luckily, [Chris] at Clickspring is currently in the business of recreating the tools and technologies that would have been used in ancient times, and he’s made a wonderful video on precision soft soldering the old-fashioned way. The video below is part of a side series he’s been working on while he builds a replica of the Antikythera mechanism, that curious analog astronomical computer of antiquity. Many parts in the mechanism were soldered, and [Chris] explores plausible methods using tools and materials known to have been available at the time the mechanism was constructed (reported by different historians as any time between 205 BC and 70 BC or so). His irons are forged copper blocks, his heat source is a charcoal fire, and his solder is a 60:40 mix of lead and tin, just as we use today. He vividly demonstrates how important both surface prep and flux are, and shows both active and passive fluxes. He settled on rosin for the final joints, which turned out silky smooth and perfect; we suspect it took quite a bit of practice to get the technique down, but as always, [Chris] makes it look easy.