<p>Silicone socks are <strong>safe to use</strong>, provided your <strong>printer is safely operating</strong> and you are <strong>using the silicone  socks in their operating temperature range</strong>.</p>
<hr />
<h1>Your current setup is NOT SAFE!</h1>
<hr />
<p>When the heater element falls out of the heater block (that should not happen in the first place, please secure it correctly) and heats up to about 800 °C this means that the printer has no active <a href="/q/8466">Thermal Runaway Protection (TRP)</a> enabled. Basically, when the thermistor doesn't measure a temperature rise while the voltage to the heater element is being scheduled, the firmware should shut down the voltage to the heater element. When this fails, the heater element can reach dangerously high temperatures to start burning anything that can catch a flame on touch. In deliberate tests, heaters have been able to melt the aluminium of the hotend:</p>
<p><div class="youtube-embed"><div>
                <iframe width="640px" height="395px" src="https://www.youtube.com/embed/qVjWg2vuWzk?start=129"></iframe>
            </div></div></p>
<p>You <strong>should be worried at this point</strong> as you see <a href="https://www.thissmarthouse.net/dont-burn-your-house-down-3d-printing-a-cautionary-tale/" rel="noreferrer">from the link you provided</a> what happens if the heater is not shut off when the heater element is disconnected from the heater block:</p>
<p><a href="https://i.sstatic.net/eJput.png" rel="noreferrer" title="Burnt Anet A8 as a result of inactive TRP and heater cartridge falling out of the heater block"><img src="https://i.sstatic.net/eJput.png" alt="Burnt Anet A8 as a result of inactive TRP and heater cartridge falling out of the heater block" title="Burnt Anet A8 as a result of inactive TRP and heater cartridge falling out of the heater block" /></a></p>
<p>Please <strong>fix your printer ASAP</strong> by uploading a proper firmware with enabled TRP protection before proceeding to print anything or at least don't let it print without supervision and proper smoke/fire detection devices.</p>

CC BY-SA 4.0
2019-11-19T07:20:37.453Z
2019-11-22T08:10:54.373Z
2020-06-18T08:29:41.667Z
0scar
<p>Neither your thermistor nor your heater cartridge should ever be capable of becoming loose from your hotend, let alone the fact it's capable of reaching 800&nbsp;&deg;C before your printer even notices (This is a massive issue in itself!!!)</p>

<p>Silicone socks are safe, unless you're printing materials with extremely high melting points, which is <em>usually</em> never.</p>

<p>If you're concerned it's going to autoignite mid-print, you have much bigger issues surrounding your hotend than a silicone sock.</p>

CC BY-SA 4.0
2019-11-19T10:15:26.397Z
@steveantwan it's not opinion based but PLEASE replace your firmware for one with TRP.
Trish
CC BY-SA 4.0
2019-11-19T04:05:27.430Z
2019-11-19T07:52:46.977Z
2019-11-19T07:52:46.977Z
craftxbox
<p>It's fairly common for E3D to sell silicone socks for their hot ends. There are also other companies that sell these silicone socks for their hot end cartridges.</p>

<p>According to a brief internet search, it seems the ignition temperature of silicone is surprisingly low - around 450&nbsp;&deg;C. This surprised me because I was under the impression silicone would just burn  / evaporate if it were heated up to a much higher temperature.</p>

<p>If my thermistor/<a href="https://www.thissmarthouse.net/dont-burn-your-house-down-3d-printing-a-cautionary-tale/" rel="nofollow noreferrer">heatrod</a> slips off, my heatrod will glow into an orange temperature during thermal runway. This only happens briefly, but its color indicates it is reaching a temperature around 790&nbsp;&deg;C. </p>

<p>So, are silicone socks safe? Couldn't they ignite fairly easily?</p>

<p><a href="https://i.sstatic.net/XAH7r.png" rel="nofollow noreferrer" title="Incandescence chart for iron"><img src="https://i.sstatic.net/XAH7r.png" alt="Incandescence chart for iron" title="Incandescence chart for iron"></a></p>

CC BY-SA 4.0
2019-11-19T03:54:14.373Z
The more pressing issue here is not whether the sock will ignite, it's why your heater is reaching 800 °C in the first place. This should almost never happen under any circumstances in normal operation, as the upper limit for printing temperature on most common materials is 280 °C. Either your thermal-runaway protection is not sufficient in any way, or you're pumping **WAY** too much energy into your hotend.
craftxbox
CC BY-SA 4.0
2019-11-19T03:55:07.183Z
If your heatrod falls off it can happen! https://www.thissmarthouse.net/dont-burn-your-house-down-3d-printing-a-cautionary-tale/ If your silicone sock accidentally touches the heatrod during application - maybe?  Silicone is actually about as combustible as cardboard - why would you put cardboard around your heater end
K Mmmm
CC BY-SA 4.0
2019-11-19T03:57:51.383Z
I dont understand what this article is supposed to be clearing up about, only that the fact your cartridge being capable of decoupling itself is an even larger problem.
craftxbox
CC BY-SA 4.0
2019-11-19T03:59:29.013Z
I was just surprised. I mod my hot ends, and knowing this now, I don't feel responsible enough to trust myself with a  silicone sock, personally. And it's not just me - a bad thermistor from the manufacturer or basic slip-up could cause this.
K Mmmm
CC BY-SA 4.0
2019-11-19T07:09:36.867Z
You are linking to a printer that had no [Thermal Runaway Protection](/q/8466) enabled. It seems that your printer doesn't either, please fix that first!
0scar
CC BY-SA 4.0
2019-11-19T10:23:18.493Z
note that your Incandescence chart is technically the iron one, the one for aluminum is a little different (by a margin of some hundred degrees). Note that Aluminium (which your heater block is made of) melts at 660 °C, so your most worrying item should be the block, which will melt, drip and melt anything below if this goes on for a couple seconds like seen [here](https://www.youtube.com/watch?v=qVjWg2vuWzk)
Trish
CC BY-SA 4.0
2019-11-19T13:38:16.797Z
Just as a by-the-way: there are heat resistant silicones that will burn very slowly and retard fires even if you cross into the high temperatures. Here is an example (Disclaimer, I have worked for the company who made this ad) https://www.youtube.com/watch?v=-xcxDTNbzho
Stian
CC BY-SA 4.0
2019-11-19T14:53:07.473Z
While it is good fire safety practice to keep around as few inflammable material as possible, don't forget that the usual filaments are flammable, too. Ultimater lists an ignition temp for their PLA of 388 °C and thermal decomposition from 250 °C (https://ultimaker.com/download/74613/UM180816%20SDS%20PLA%20RB%20V11.pdf)
cbeleites
CC BY-SA 4.0
2019-11-20T11:43:40.753Z
Today I learned that "sock" can refer to other stuff than just footwear. Also, congratulations for reaching the Hot Network Questions!
John Dvorak
<safety>
Are silicone socks safe?
K Mmmm
# Are silicone socks safe?

(Asked by: username_0 on 2019-11-19)

It's fairly common for E3D to sell silicone socks for their hot ends. There are also other companies that sell these silicone socks for their hot end cartridges.

According to a brief internet search, it seems the ignition temperature of silicone is surprisingly low - around 450 °C. This surprised me because I was under the impression silicone would just burn / evaporate if it were heated up to a much higher temperature.

If my thermistor/[heatrod](https://www.thissmarthouse.net/dont-burn-your-house-down-3d-printing-a-cautionary-tale/) slips off, my heatrod will glow into an orange temperature during thermal runway. This only happens briefly, but its color indicates it is reaching a temperature around 790 °C.

So, are silicone socks safe? Couldn't they ignite fairly easily?

[![Incandescence chart for iron](https://i.sstatic.net/XAH7r.png "Incandescence chart for iron")](https://i.sstatic.net/XAH7r.png "Incandescence chart for iron")

**Tags:** safety

> **Comments:**
> **username_1**: The more pressing issue here is not whether the sock will ignite, it's why your heater is reaching 800 °C in the first place. This should almost never happen under any circumstances in normal operation, as the upper limit for printing temperature on most common materials is 280 °C. Either your thermal-runaway protection is not sufficient in any way, or you're pumping **WAY** too much energy into your hotend.  
> **username_0**: If your heatrod falls off it can happen! https://www.thissmarthouse.net/dont-burn-your-house-down-3d-printing-a-cautionary-tale/ If your silicone sock accidentally touches the heatrod during application - maybe?  Silicone is actually about as combustible as cardboard - why would you put cardboard around your heater end  
> **username_1**: I dont understand what this article is supposed to be clearing up about, only that the fact your cartridge being capable of decoupling itself is an even larger problem.  
> **username_0**: I was just surprised. I mod my hot ends, and knowing this now, I don't feel responsible enough to trust myself with a  silicone sock, personally. And it's not just me - a bad thermistor from the manufacturer or basic slip-up could cause this.  
> **username_2**: You are linking to a printer that had no [Thermal Runaway Protection](/q/8466) enabled. It seems that your printer doesn't either, please fix that first!  
> **username_3**: note that your Incandescence chart is technically the iron one, the one for aluminum is a little different (by a margin of some hundred degrees). Note that Aluminium (which your heater block is made of) melts at 660 °C, so your most worrying item should be the block, which will melt, drip and melt anything below if this goes on for a couple seconds like seen [here](https://www.youtube.com/watch?v=qVjWg2vuWzk)  
> **username_4**: Just as a by-the-way: there are heat resistant silicones that will burn very slowly and retard fires even if you cross into the high temperatures. Here is an example (Disclaimer, I have worked for the company who made this ad) https://www.youtube.com/watch?v=-xcxDTNbzho  
> **username_5**: While it is good fire safety practice to keep around as few inflammable material as possible, don't forget that the usual filaments are flammable, too. Ultimater lists an ignition temp for their PLA of 388 °C and thermal decomposition from 250 °C (https://ultimaker.com/download/74613/UM180816%20SDS%20PLA%20RB%20V11.pdf)  
> **username_6**: Today I learned that "sock" can refer to other stuff than just footwear. Also, congratulations for reaching the Hot Network Questions!  

---

## 2 answers

### Answer by username_1 on 2019-11-19. Score: 19 | Accepted answer

Neither your thermistor nor your heater cartridge should ever be capable of becoming loose from your hotend, let alone the fact it's capable of reaching 800 °C before your printer even notices (This is a massive issue in itself!!!)

Silicone socks are safe, unless you're printing materials with extremely high melting points, which is *usually* never.

If you're concerned it's going to autoignite mid-print, you have much bigger issues surrounding your hotend than a silicone sock.

> **Comments:**
> **username_3**: @steveantwan it's not opinion based but PLEASE replace your firmware for one with TRP.  

---

### Answer by username_2 on 2019-11-19. Score: 19

Silicone socks are **safe to use**, provided your **printer is safely operating** and you are **using the silicone socks in their operating temperature range**.

---

# Your current setup is NOT SAFE!

---

When the heater element falls out of the heater block (that should not happen in the first place, please secure it correctly) and heats up to about 800 °C this means that the printer has no active [Thermal Runaway Protection (TRP)](/q/8466) enabled. Basically, when the thermistor doesn't measure a temperature rise while the voltage to the heater element is being scheduled, the firmware should shut down the voltage to the heater element. When this fails, the heater element can reach dangerously high temperatures to start burning anything that can catch a flame on touch. In deliberate tests, heaters have been able to melt the aluminium of the hotend:

You **should be worried at this point** as you see [from the link you provided](https://www.thissmarthouse.net/dont-burn-your-house-down-3d-printing-a-cautionary-tale/) what happens if the heater is not shut off when the heater element is disconnected from the heater block:

[![Burnt Anet A8 as a result of inactive TRP and heater cartridge falling out of the heater block](https://i.sstatic.net/eJput.png "Burnt Anet A8 as a result of inactive TRP and heater cartridge falling out of the heater block")](https://i.sstatic.net/eJput.png "Burnt Anet A8 as a result of inactive TRP and heater cartridge falling out of the heater block")

Please **fix your printer ASAP** by uploading a proper firmware with enabled TRP protection before proceeding to print anything or at least don't let it print without supervision and proper smoke/fire detection devices.


---

