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"Salt method" for bonding prints does not work on ABS

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Just for your information: my "salt method" to glue models to the glass plate (=by wiping the glass plate with very salt water, and let it dry into a thin mist of salt) does *not* work with ABS+ filament. Even simple models warped and came off, so I had to abort them.

I tried it on a spool of ABS+ that I still had laying around, but never used before.

(Note: ABS+ is supposed to be an improved ABS, which should have less warping than standard ABS. But I don't know the precise chemical composition. I guess it may have a bit more butadiene than usual, to make it softer and warp less? At least, it is much more flexible than the usual ABS of Lego-bricks or Playmobil toys, and it has a somewhat "rubbery" feeling.)

Very weird was that the first layers seemed to "explode" against the salt. It made a crackling sound and foamed. After two layers that foaming and crackling stopped, and it printed very smooth. Until the bottom warped and the model came off, so I had to abort the print. The foaming and crackling is similar to what we could expect from too much moisture. But the filament was very well vacuum packed with a big desiccant pack, so it doesn't seem to be moisture from the filament. (And otherwise it wouldn't have stopped crackling after the first two layers.) So it seems rather to be moisture caught in the salt, or a chemical reaction to the salt.

Weird too is that atomic methods wouldn't work: the filament kept breaking, instead of coming loose. This even though when cold the filament was very flexible, and I could bend it 180° without breaking. It seems it got totally glued to the nozzle walls, which is weird, since molten ABS is supposed to *not* stick to metal, contrary to PLA. Or maybe it got glued to the black residu or the etched surface from previous PLA in the nozzle?

Since I could not do atomic pulls, I had to flush the remains through the nozzle by pushing with fresh PLA filament, at 220°C. Fortunately this worked, although the ABS+ and PLA seemed to "fight" a bit: they didn't mix well while flushing. After flushing with 15cm of PLA filament, I could succesfully do atomic methods with PLA again.

Anyway, for the "salt method", in summary that gives:

- PLA: excellent bonding, even difficult models do not lift corners. Recommended.

- ABS+: very poor bonding, even very simple models warp, come off, and fail. ABS reacts to the salt or moisture in the salt. Thus definitely *not* recommended. Try any of the wood glue or glue-stick methods, or 3DLAC, or so, instead.

- PET: no personal experience, but some time ago ultiarjan reported poor bonding (worse than with the glue-stick), and warping. Thus not recommended either.

- Other materials: no experience. If you would have tried the "salt method" on any other materials, please let us know the results, good or bad.

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I've never had PLA lifting issues, glue stick once a month seems to be enough residual grip.. are you just trying different substances on your print bed or has somebody previously indicated that salt water would work?

Other suggestions:

maple syrup

beer

milk

rubber cement

flour / water

let us know what works best / how that cake turns out!!!

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...

are you just trying different substances on your print bed or has somebody previously indicated that salt water would work?

...

 

It took some time and observation to find this method, there was nothing random about it.

I often have difficult models: very long, thick, 100% filled, with chamfers at the bottoms. So they exert a lot of warping forces, even for PLA.

Printing on bare glass worked only in freezing cold weather when the air was very dry. But even then corners would lift. In moist weather, printing on bare glass did not work at all, and there would be no bonding at all. So, surface tension or surface charge seemed to play a role.

Glue stick worked reasonably, but some models got stuck too hard (those that had a very big contact surface) and were very hard to remove, so they got damaged. Other models wouldn't stick or would come off (high models with a small base and huge chamfers at the bottom, 100% filled). And the glue was messy.

At that time I did not know the cleaner "gr5 method" of dilluting wood glue 10% in water. Or smoothing the glue-stick glue with water. And 3DLAC didn't exist yet, or was not yet known. If I had known these methods, I would have tried them, and maybe never felt a need to search further.

Also, I could not use blue tape, since the bottom of my prints had to be absolutely flat, without the ridges and roughness of the tape.

So I needed to find something else.

I had also noticed that after cleaning the glass plate with soap-water or window cleaner, bonding was far worse than before. Cleaning with pure tap water worked best.

I reasoned that soap reduces bonding by reducing surface tension.

To glue something, the substrate (thing to glue) needs a higher surface tension than the glue itself. So, for 3D-printing, the glass plate would need to have a higher surface tension than the filament, I thought, for it to stick. Otherwise the filament would just curl up into a ball and only stick to itself, not to the glass.

Thus I needed something that would *increase* surface tension, and then maybe that would increase bonding too. One of the few commonly available chemicals to increase surface tension is salt, NaCl. That is how I got the idea of wiping the glass plate with salt water.

I don't know if my reasoning is correct, it could even be totally wrong. But at least the method works very well for PLA (not for ABS). For PLA the bonding is very strong when the glass plate is hot at 60°C. But there is no bonding at all after cooling down to room temp. So, for me this is the perfect solution. I used several colors of Ultimaker PLA and colorFabb PLA/PHA, and all work equally well.

I hoped it would also work for filaments that are chemically related to PLA. But for oil-based filaments such as ABS, it obviously doesn't work, and I had not expected it to (but there is always some faint hope of course).

That is the background of it, in short.

I haven't tried anything else. So, no random food stuff, syrup, milk, cornflakes, or whatever. :)

(Although trying sugar syrup would make sense, since it is sticky, and is water-soluble. So you can get the print off by dissolving the sugar. Some people seem to use this with good results. But I haven't tried, no need to.)

For the full manual, full background, and pictures of the salt method, see:

https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/

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a while ago I tried the sugar method when there was no glue around, but somebody left his sugar for his coffee... So I remembered this post and used the sugar, with a PET print. It worked very well, compared to clean glass, the only disadvantage is that the glass plate became really sticky, like sticky, sticky and the bottom of the print took off the sugar layer and needed cleaning (sticky). But it worked...

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