3D Printing Toothpaste In The Name Of Science

October 14, 2021 by Tom Nardi 4 Comments

While we don’t often see them in the hobbyist community, 3D printers that can extrude gels and viscous liquids have existed commercially for years, and are increasingly used for biological research. [Ahron Wayne] has recently been working with such a printer as part of a project to develop a printed wound dressing made of honey and blood clotting proteins, but for practice purposes, wanted to find a cheaper and more common material that had similar extrusion properties.

The material he settled on ended up being common toothpaste. In the video below you can see him loading up the cartridge of a CELLINK INKREDIBLE+ bioprinter with the minty goop, which is then extruded through a thin blunt-tip needle by compressed air. After printing out various shapes and words using the material, often times directly onto the bristles of a toothbrush, he’s come up with a list of tips for printing similarly viscous substances.

First and foremost, go slow. [Ahron] says the material needs a moment to contract after being extruded if it’s going to have any hope of supporting the next layer of the print. Thick layer heights are a necessity, as is avoiding sharp curves in your design. He also notes that overhangs must be avoided, and though it probably goes without saying, clarifies that an object printed from toothpaste will never be able to support anything more than its own weight.

In addition to the handful of legitimate DIY bioprinters that have graced these pages over the years, we’ve seen the occasional chocolate 3D printer that operated on a similar principle to produce bespoke treats, so the lessons learned by [Ahron] aren’t completely lost on the hacker and maker crowd. Who knows? Perhaps you’ll one day find yourself consulting this video when trying to get a modified 3D printer to lay down some soldering paste.

Continue reading “3D Printing Toothpaste In The Name Of Science” →

You Can Put Toothpaste In The Tube (With Effort)

July 5, 2021 by Bryan Cockfield 20 Comments

Old wives’ tales, folk knowledge, common sayings, and even cliches and idioms are often taken as givens since they form an often unnoticed part of our vocabulary and culture. There’s so many examples that it’s possible to fill a 17-season TV show busting potential myths like these, and even then there are some that slipped by. For example, the saying “you can’t put toothpaste back in the tube” which, as it turns out, is not as impossible as we might be led to believe.

This video is the product of [Tyler Bell] who has taken this idiom on as a challenge. To figure out if it was possible he first got to work building a vacuum chamber, which turned out to be a little easier than he thought it would be. After cutting a piece of polycarbonate tube and sanding it down, all that was needed were some rubber gaskets and fittings for the vacuum pump.

From there, the theory was to put an empty toothpaste tube into the vacuum chamber, pump all of the air out, and let atmospheric pressure “push” the toothpaste back into the tube. During [Tyler]’s first run he thought that it had worked successfully but it turned out that he had just inflated the empty toothpaste tube like a balloon. Further iterations were able to return some of the toothpaste to the tube, but each time some air would eventually work its way into the toothpaste which would immediately fill the remaining space in the tube with air rather than toothpaste.

While not completely successful, he was able to get some toothpaste back into the tube with a relatively small bill of materials. It’s not likely that this experiment will result in a change of this particular idiomatic expression, but it was interesting to put it to the test nonetheless. For other instances of toothpaste and its relationship to tubes, both inside and out, be sure to check out this recent piece on various methods of toothpaste storage.

Continue reading “You Can Put Toothpaste In The Tube (With Effort)” →

You Can’t Put The Toothpaste Back In The Tube, But It Used To Be Easier

June 24, 2021 by Kristina Panos 60 Comments

After five years of research, Colgate-Palmolive recently revealed Australia’s first recyclable toothpaste tube. Why is this exciting? They are eager to share the design with the rest of the toothpaste manufacturers and other tube-related industries in an effort to reduce the volume of plastic that ends up in landfills. It may not be as life-saving as seat belts or the Polio vaccine, but the move does bring Volvo and OG mega open-sourcer Jonas Salk to mind.

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.

Continue reading “You Can’t Put The Toothpaste Back In The Tube, But It Used To Be Easier” →

Trials Begin For Lozenge That Rebuilds Tooth Enamel

June 2, 2021 by Kristina Panos 48 Comments

For all the cool regenerative tricks the human body can do, it’s kind of weird that we only have one shot at tooth enamel with no way to get it back. That may be about to change, as researchers at the University of Washington have developed a lozenge that rebuilds this precious protective coating a few microns at a time and are taking it to the trial stage. Could it really work? It’s certainly something to chew on.

The lozenge uses a genetically-engineered peptide (a chain of amino acids) derived from a protein that’s involved in developing enamel in the first place, as well as with the formation of the root surface of teeth. Inside the lozenge, this peptide works alongside phosphorus and calcium ions, which are the building blocks of tooth enamel. It’s designed to bind to damaged enamel without harming the gums, tongue, or other soft tissues of the mouth.

The researchers have already verified the efficacy on teeth extracted from humans, pigs, and rats, so the trials will largely revolve around comparing it to other whitening methods and documenting their findings.

One added advantage is that the new enamel the lozenges produce is really white, because it’s brand new. These lozenges sound like an all-around great solution, especially compared with traditional whitening techniques that often make enamel weaker. The researchers are also developing an over-the-counter toothpaste and some kind of solution for hypersensitivity, which is right up our alley.

We are skeptical of course, because nothing in history thus far has been able to regenerate enamel. Then again, yours truly uses toothpaste with nano-hydroxyapatite, which is touted as a non-toxic version of the same mineral that makes up teeth and bones. Skepticism abounds with that stuff, too, although my grill looks better to me. But why settle for new enamel when you could regrow entire teeth?

Main image by Eric Moreau and thumbnail image by Kevin Bation via Unsplash

Toothpaste Diode

March 16, 2011 by Kevin Dady 39 Comments

While reading the back of a tube a toothpaste [Underling] noticed that one of the ingredients was hydrated silica, gears turned, sparks flew and he wondered if he could possibly make a transistor out of the stuff. After thinking about it he decided that making a diode out of toothpaste would be easier and still prove the idea.

The quick n dirty explanation of this is he smeared some toothpaste on a bit of chrome and set it on fire with a propane torch. When set on fire the result is silica and sodium, heat causes the sodium to bond with the silica and since sodium is negatively charged this forms an n-type semiconductor or half of the diode. Chrome is used for the second half of the diode, for a few reasons, he had some lying around, its positivity charged, and the toothpaste contains a little bit of lye which oxidizes the chrome and burns off, bonding the silica to the metal.

What is left is a thin layer of chrome doped silicon under a layer of sodium doped silicon, which in spots where everything is perfect, acts like a diode, blocking current in one direction but not the other.