Re-inforcing 3D prints with salt

[Improflow]

I saw this process a couple of days ago about encasing 3D prints in ultra fine salt and reheating to impregnate the plastic with salt. Has anyone tried this out?

https://hackaday.com/2020/09/23/reforming-3d-prints-with-salt-and-heat/

[BrickHaus]

I recall seeing this on the forum here a while back. I still randomly think about the process and wonder if it works as well as the video shows.

[SignOfZeta]

Yeah, that sounds like one of those videos where they make flan in a milk container (never actually done).

Salt itself isn’t strong or hard, it will also just…wash right the heck off because it’s salt, so for this to be meaningful there would have to be some sort of chemical process going on with the plastic…what’s that then?

[Grendel]

I reasonable proof of concept that could be then applied to other materials with further experimentation.

[OpusX]

If I recall the point of the salt is not to impregnate the item, but to be used as a structural packing agent, so one can heat anneal or weld the layers together during a baking process. This should, in theory, laminate the layers together making a more solid piece.

[SignOfZeta]

Further reading/watching would seem to indicate you are correct. That’s exactly what it is. When the whole process is seen in the video it makes much more sense. However it’s very time consuming making me wonder why the part shown, a weak-ass sub-Ikea grade plastic angle bracket, was ever 3D printed in the fist place. You could probably buy a box of 100 steel brackets off Ali express or even have them made locally for all the man hours he put into that thing.

For MCB style “artisanal pump handle” stuff it sounds like potentially a very good idea. For most things though it just multiplies the already massive time it takes to 3D print something and in the end you still have crappy lumpy plastic.

[Tracker]

seconding this, PLA shrinks if you heat up a print, if you pack the inside and the outside to prevent them from shrinking then yeah it allows all the layers to seal together i assume this method doesnt work well with anything less than 100% infill..

but you might be onto something for it making a pump handle though..

solid prints are inefficient as all hell though.. that bracket he made probably took many extra hours to print because of all the extra plastic

i wonder if theres an easier way, because its more about containing the shape, wonder if you could do a super fine powder like corn starch and use a vibrating surface to make it pack itself...

[Rainmaker]

Yeah, i think this would be more accurately referred to as Annealing in salt.
annealing does do some cool things to printed parts. it has some practical application for sure.

[Spider!]

Was there annealing in sand earlier?

[Rainmaker]

I don't know for sure about annealing in sand, though it would probably work similarly because the principle is the same. i think salt is probably better since it's water soluble, sand might get stuck to the surface of the part.

I've annealed some parts by just putting them in the oven at about 165F for an hour or so. But that method is really only good for parts that don't have critical dimensions, because the downside is that there is definitely some deformation. Doing it like the vidio in the OP, the salt helps keep deformation to a minimum