We’ve all got our favorite hand tools, and while the selection criteria are usually pretty subjective, it usually boils down to a combination of looks and feel. In our opinion, the king of both these categories when it comes to screwdrivers is those clear, hard acetate plastic handles, which are a joy to use — at least until the plastic starts to degrade and exude a characteristically funky aroma.

But perhaps we can change that if these experiments on screwdriver “mange” hold up. That’s [357magdad]’s unappealing but accurate description of the chemical changes that eventually occur in the strong, hard, crystal-clear handles of your favorite screwdrivers. The polymer used for these handles is cellulose acetate butyrate, or CAB, which is mostly the same cellulose acetate that replaced the more explode-y cellulose nitrate in things like pool balls and movie film, except with some of the acetate groups replaced with a little butyric acid. The polymer is fine at first, but add a little UV light and over time the outer layer of CAB decomposes into a white flaky cellulose residue while the butyric acid volatilizes, creating the characteristic odor of vomitus. Lovely.

In the video below, [357magdad] takes a look at different concoctions that all allegedly cure the mange. TL, DW; it was a dunk in household ammonia that performed the best, well ahead of other common agents like vinegar and bleach. The ammonia — or more precisely, ammonium hydroxide — works very quickly on the cellulose residue, dissolving it readily and leaving the handle mange-free and looking nearly new after some light scrubbing. None of the other agents came close, although acetone did manage to clear up the mange a bit, at the cost of softening the underlying CAB in a process that’s probably similar to acetone smoothing ABS prints.

As for the funky smell, well, the results were less encouraging. Nothing really got rid of the pukey smell, even a roll in baking soda. We suspect there won’t be much for that, since humans can detect it down to 10 parts per million. Consider it the price to pay for a nice-looking screwdriver that feels so good in your hand.

Researchers demonstrate sustainable 3D printing by using poly(N-isopropylacrylamide) solutions (PNIPAM), which speedily and reliably turn solid by undergoing a rapid phase change when in a salt solution.

This property has been used to 3D print objects by using a syringe tip as if it were a nozzle in a filament-based printer. As long as the liquid is being printed into contact with a salt solution, the result is a polymer that solidifies upon leaving the syringe.

What’s also interesting is that the process by which the PNIPAM-based solutions solidify is entirely reversible. Researchers demonstrate printing, breaking down, then re-printing, which is an awfully neat trick. Finally, by mixing different additives in with PNIPAM, one can obtain different properties in the final product. For example, researchers demonstrate making conductive prints by adding carbon nanotubes.

While we’ve seen the concept of printing with liquids by extruding them into a gel bath or similar approach, we haven’t seen a process that prides itself on being so reversible before. The research paper with all the details is available here, so check it out for all the details.