Question about ABS hygroscopy

[dpmacri]

I've been doing things recently to try to keep my ABS filament dry since I started to get some lousy prints after a spool of SeeMeCNC neon green had sat out for about a month. I noticed that it visibly looked different and the print quality was getting pretty poor. Switching to a new spool eliminated the print problems. So I went about working on drying out that filament and looking into ways to keep new filament dry.

In the process I started thinking about ABS and the fact that Legos are made out of ABS. And I began to wonder why Legos don't end up with the discoloration problem like I saw or, in general, any kind of change in their characteristics over time (old legos snap together fine with new ones). Certainly, my kids aren't putting their Legos away in low relative-humidity containers

Maybe there's a simple explanation, but I'm curious if anyone actually knows the answer.

[Eaglezsoar]

I've been doing things recently to try to keep my ABS filament dry since I started to get some lousy prints after a spool of SeeMeCNC neon green had sat out for about a month. I noticed that it visibly looked different and the print quality was getting pretty poor. Switching to a new spool eliminated the print problems. So I went about working on drying out that filament and looking into ways to keep new filament dry.

In the process I started thinking about ABS and the fact that Legos are made out of ABS. And I began to wonder why Legos don't end up with the discoloration problem like I saw or, in general, any kind of change in their characteristics over time (old legos snap together fine with new ones). Certainly, my kids aren't putting their Legos away in low relative-humidity containers

Maybe there's a simple explanation, but I'm curious if anyone actually knows the answer.

I'm not sure but I would imagine that Legos have an additive that prevents them from being able to absorb moisture.

[dpmacri]

I've been doing things recently to try to keep my ABS filament dry since I started to get some lousy prints after a spool of SeeMeCNC neon green had sat out for about a month. I noticed that it visibly looked different and the print quality was getting pretty poor. Switching to a new spool eliminated the print problems. So I went about working on drying out that filament and looking into ways to keep new filament dry.

In the process I started thinking about ABS and the fact that Legos are made out of ABS. And I began to wonder why Legos don't end up with the discoloration problem like I saw or, in general, any kind of change in their characteristics over time (old legos snap together fine with new ones). Certainly, my kids aren't putting their Legos away in low relative-humidity containers

Maybe there's a simple explanation, but I'm curious if anyone actually knows the answer.

I'm not sure but I would imagine that Legos have an additive that prevents them from being able to absorb moisture.

If that's true, then I'd be curious to know if anyone has ground up Legos in a Filabot or similar extruder and whether or not the resulting filament is no longer hygroscopic.

[Eaglezsoar]

I've been doing things recently to try to keep my ABS filament dry since I started to get some lousy prints after a spool of SeeMeCNC neon green had sat out for about a month. I noticed that it visibly looked different and the print quality was getting pretty poor. Switching to a new spool eliminated the print problems. So I went about working on drying out that filament and looking into ways to keep new filament dry.

In the process I started thinking about ABS and the fact that Legos are made out of ABS. And I began to wonder why Legos don't end up with the discoloration problem like I saw or, in general, any kind of change in their characteristics over time (old legos snap together fine with new ones). Certainly, my kids aren't putting their Legos away in low relative-humidity containers

Maybe there's a simple explanation, but I'm curious if anyone actually knows the answer.

I'm not sure but I would imagine that Legos have an additive that prevents them from being able to absorb moisture.

If that's true, then I'd be curious to know if anyone has ground up Legos in a Filabot or similar extruder and whether or not the resulting filament is no longer hygroscopic.

I don't know about grinding up Legos but if the manufacturers wanted to do so, they could create filaments that not hygroscopic. Let's hope that is what the future holds for those of us who use their filaments.

[cope413]

Legos absorb moisture, but you don't notice because ABS only absorbs a relatively small amount by volume.

However, when you're extruding it, that small amount of moisture can make a huge difference because the tiny drops of water vaporize in the hot end and cause air bubbles, and changes in extrusion temperature which negatively affect print quality.

ABS is hygroscopic, but is not chemically altered by the presence of moisture while extruding - unlike Nylon and PC - which actually hydrolyze and get weaker.

We will actually begin selling drying boxes very soon (maybe as soon as later this week) in order to protect your filament and maintain high print quality, and we'll have a full write-up/explanation about the effects of moisture on filament and printing.

[dpmacri]

Legos absorb moisture, but you don't notice because ABS only absorbs a relatively small amount by volume.

However, when you're extruding it, that small amount of moisture can make a huge difference because the tiny drops of water vaporize in the hot end and cause air bubbles, and changes in extrusion temperature which negatively affect print quality.

ABS is hygroscopic, but is not chemically altered by the presence of moisture while extruding - unlike Nylon and PC - which actually hydrolyze and get weaker.

We will actually begin selling drying boxes very soon (maybe as soon as later this week) in order to protect your filament and maintain high print quality, and we'll have
a full write-up/explanation about the effects of moisture on filament and printing.

Thanks for the explanation! Depending on the price, I'll likely be buying one of your boxes when they're available

[CJGerard]

Depending on the price, I'll likely be buying one of your boxes when they're available

hehehe

[Jimustanguitar]

I appreciate that explanation as well. I'd heard others say that ABS couldn't be affected by moisture because it wasn't water soluble like PLA so it couldn't absorb it... You used bigger words, so I believe you

[Durandal]

If anyone could figure out a way to move the moisture from filament to a cigar humidor, without stinking up the sticks, I'd pay top dollar for that.

[cope413]

I appreciate that explanation as well. I'd heard others say that ABS couldn't be affected by moisture because it wasn't water soluble like PLA so it couldn't absorb it... You used bigger words, so I believe you

Yeah, that's definitely not accurate information on multiple levels. First, PLA isn't water soluble. Second, hygroscopy has nothing to do with water-solubility. Third, PLA used in 3D printing is actually MORE hygroscopic than ABS in the amount of moisture it can absorb by weight.