If you check the MaterialSafetyDataSheet of Ninjaflex, a popular 3D printing material.

3D Printing
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1

If you check the MaterialSafetyDataSheet of Ninjaflex, a popular 3D printing material. Which is extremely flexible. You’ll find the following bit:

HAZARDOUS DECOMPOSITION PRODUCTS: Carbon monoxide, carbon dioxide, hydrogen cyanide
THERMAL DECOMPOSITION: No decomposition if stored and handled as prescribed/indicated. Thermal
decomposition above the indicated temperature is possible ( > 230 °C). Prolonged thermal loading can result in
products of degradation being given off.

The parts that are interesting are:
“hydrogen cyanide” and “Thermal decomposition above the indicated temperature is possible ( > 230 °C)”

Which simply says, that if you heat ninjaflex above 230C, it can give off “hydrogen cyanide”. As for hydrogen cyanide:

You can find the datasheet easy with google: Google

Ok, I find it quite scary, but I might be missing something? Any chemist in our mids?

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PLA doesn’t have significant amounts of nitrogen, unlike plastics that have this warning. Most likely HCN won’t be produced in a deadly amount when printing plastics because we aren’t prolongedly heating any plastics – it’s in and out of the hot end rather quick. But, it never hurts to keep the room ventilated.

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This isn’t something particularly new. All sorts of currently in use plastics will thermally decompose into unpleasant things (frequently including hydrogen cyanide).

That’s why you don’t significantly overheat your filament. If you get a plastic to the point of thermal degradation, it’s not going to be useful as a printing material anyway. These are not temperatures you’ll be hitting in normal usage.

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But 230C isn’t significantly overheating, as they recommend 225C as maximum printing temperature.

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@Mark_Rehorst If ABS does the same thing, then it’s even less of an issue. I’ve never heard anything about people dying from the decomposition of the LEGO in their house.

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Yes, burning plastics produce lots of nasty stuff.

7

A lot of Ninjaflex has been used. Anyone hear any complaints. I am fine with PLA in public places. I’ve exposed thousands to it with my Bukito and have had no 0 zero complaints.

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@Kenneth_Cummings Devils advocate here.
Cigarettes were generally considered “safe” until the 80s due to the same logic. Look at their contents.

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“A lot of Ninjaflex has been used. Anyone hear any complaints.” Maybe they all died? Hard to complain then :wink:

I consulted a chemist as well. Which resulted in a bit of a vague answer and pretty much “we do not really know it”. The problem is that we currently do not know in which amounts this chemical is released, and how easy it is formed. For example, he said that to form HCN in ABS, the chemical process can happen, but it’s a complex chain, so it won’t happen in great scale. For ninjaflex it’s harder to judge as he knew less about the chemical composition.

PLA on the other hand, he was quite clear about that. As it does not decompose into anything really harmful. So yes, @Kenneth_Cummings it seems PLA is the safest option right now.

Finally, because something is potentially harmful does not mean we should do it. We just need to be well informed and not assume everything is 100% safe. We do a lot of unsafe/harmful things every day.