<p>All you have to do is submerge your sample of glass into mineral oil. If it seems to disappear, it's borosilicate.</p>

CC BY-SA 4.0
2018-10-10T10:40:43.287Z
Hi and welcome to SE.3DP! Do you have a link, image or video to demonstrate this visual effect? In addition, please keep comments friendly... if you disagree with someone else's answer there is no need to denigrate it. You may also wish to edit your answer, and fix the typos. Thanks :-)
Greenonline
CC BY-SA 4.0
2020-11-23T14:05:40.540Z
https://www.exploratorium.edu/snacks/disappearing-glass-rods
user77232
CC BY-SA 4.0
2018-10-10T10:12:29.130Z
2018-10-10T10:44:10.237Z
2018-10-10T10:44:10.237Z
Anonymous
<p>Some more details about <a href="https://3dprinting.stackexchange.com/questions/3098/how-can-i-determine-whether-my-borosilicate-glass-is-fake-or-not#comment11269_7157">a suggestion</a> made to the answer on <a href="https://3dprinting.stackexchange.com/questions/3098/how-can-i-determine-whether-my-borosilicate-glass-is-fake-or-not/7157#7157">How can I determine whether my borosilicate glass is fake or not?</a>.</p>
<p>Submerging the glass in mineral oil should make it disappear if it is borosilicate glass, as demonstrated below. This phenomenon is known as <a href="https://en.wikipedia.org/wiki/Index-matching_material" rel="nofollow noreferrer">the &quot;index matching&quot; effect</a>. The index of refraction of borosilicate glass is n=1.47, and that of mineral oil is also around n=1.47, depending on the type of mineral oil used. However, as mentioned in <a href="https://3dprinting.stackexchange.com/questions/3098/how-can-i-determine-whether-my-borosilicate-glass-is-fake-or-not/21693#comment40845_21693">this comment</a>, other types of glass might have a similar or close refraction index, making it hard to distinguish borosilicate from non-borosilicate using this test alone.</p>
<blockquote>
<p>The borosilicate glass and the oil have roughly the same index of refraction. When this beaker is immersed into a container of oil, the beaker becomes invisible.</p>
</blockquote>
<p><a href="https://i.sstatic.net/ol9f3.gif" rel="nofollow noreferrer" title="An animated GIF of a small beaker inside of a larger beaker and cooking oil being poured into the smaller beaker overflowing into the larger"><img src="https://i.sstatic.net/ol9f3.gif" alt="An animated GIF of a small beaker inside of a larger beaker and cooking oil being poured into the smaller beaker overflowing into the larger" title="An animated GIF of a small beaker inside of a larger beaker and cooking oil being poured into the smaller beaker overflowing into the larger" /></a></p>
<p><sup>Source: <a href="https://www.teachersource.com/product/the-disappearing-beaker" rel="nofollow noreferrer">The Disappearing Beaker Experiment</a></sup></p>

CC BY-SA 4.0
2023-11-28T13:12:28.117Z
This is true for most glasses other than high index optical types.  Pyrex and window glass have nearly identical refractive index.
Zeiss Ikon
CC BY-SA 4.0
2023-11-28T13:03:25.910Z
2023-11-28T15:01:00.803Z
2023-11-28T15:01:00.803Z
Bob Ortiz
<blockquote>
  <p>"toughened" glass,</p>
</blockquote>

<p>Lead, cadmium and barium would have that effect. It goes without saying that you wouldn't want that kind of glass anywhere near your neighborhood. </p>

<p>Even those items that mention borosilicate glass in the product description may have never seen any boron. </p>

<p>Some studies have found that more than 90% of items sourced from China are fraudulently labeled. There is no enforcement. </p>

<p>While stats say nothing about any particular sample, I'd certainly keep them in mind. </p>

CC BY-SA 4.0
2018-10-16T07:44:50.277Z
It might be worth sharing some of said studies - also while it says what else the glass could be, it dosen't really help OP with working out if its borosillicate glass.
Journeyman Geek
CC BY-SA 4.0
2018-10-16T07:47:11.887Z
Hi and welcome to SE.3DP. Can you provide links, sources to back up your claims? *It goes without saying that you wouldn't want that kind of glass anywhere near your neighborhood.* [Pyrex](https://en.wikipedia.org/wiki/Pyrex) will be found in your kitchen probably. *Some studies*... what studies? Do you have a link? Your answer would have more worth with sources. Thanks. Also, you aren't really answering my question, but rather questioning the morals behind Borosilicate. I just want to know how to check that it isn't just plain old vanilla glass.
Greenonline
CC BY-SA 4.0
2018-10-15T22:27:36.123Z
2018-10-16T07:43:11.157Z
2018-10-16T07:43:11.157Z
NightKnight on Cloudinsidr.com
<p>Google turned up this thread: <a href="http://arstechnica.com/civis/viewtopic.php?t=96214" rel="nofollow noreferrer">http://arstechnica.com/civis/viewtopic.php?t=96214</a></p>

<p>There don't seem to be any easy, definitive tests. You have two main options, both of which seem to require a fairly high level of laboratory skill (but nothing fancy in terms of equipment).</p>

<p>The refractive index of Borosilicate glass is very similar to vegetable oil (implying no reflection from a boundary if you have a pool of oil on the glass).</p>

<p>The density of the glass can be measured too, using a water bath. This should also be able to give a fairly accurate answer.</p>

<p>Stress testing seems the most reliable way to determine if you have a 'good' sample, but may be more expensive.</p>

CC BY-SA 3.0
2016-11-28T11:23:29.840Z
2016-11-28T11:23:29.840Z
Sean Houlihane
<p>Is there actually a way to determine whether the sheet of glass that one has received from a Chinese supplier on eBay is actually a sheet of Borosilicate glass, and not just a piece of normal glass intended for glazing purposes?</p>

<p>Are there any laminations, or markings/features, visible under a certain light or if the sheet is viewed at a particular angle?</p>

<p>I ask because most of the 200 x 300 mm sheets on eBay are priced at around £16 - £26, but there are a few priced at just £10, which still claim to be toughened glass, although they do not mention the word Borosilicate, such as this one, <a href="http://www.ebay.co.uk/itm/300x200x3mm-3D-Printer-Heated-Bed-Toughened-Glass-Clear-Build-Plate-UK-STOCK-/302067007035" rel="nofollow noreferrer">300x200x3mm 3D Printer Heated Bed Toughened Glass Clear Build Plate UK STOCK</a>. </p>

<p>To paraphrase, "Usually if things seem to good to be true, then they are probably fake." However, I wondered whether it was worth a punt as it is only £10, and then if I would be able to verify its veracity once it was in my hands.</p>

CC BY-SA 4.0
2018-10-16T13:31:42.770Z
Good question, I worked a while in labs. I think borosilicate glass was not looking greenish from the side (but I am not 100% sure). Other than that, the density is lower than of regular glass.
dgrat
<build-plate>
How can I determine whether my borosilicate glass is fake or not?
Greenonline
# How can I determine whether my borosilicate glass is fake or not?

(Asked by: username_0 on 2016-11-27)

Is there actually a way to determine whether the sheet of glass that one has received from a Chinese supplier on eBay is actually a sheet of Borosilicate glass, and not just a piece of normal glass intended for glazing purposes?

Are there any laminations, or markings/features, visible under a certain light or if the sheet is viewed at a particular angle?

I ask because most of the 200 x 300 mm sheets on eBay are priced at around £16 - £26, but there are a few priced at just £10, which still claim to be toughened glass, although they do not mention the word Borosilicate, such as this one, [300x200x3mm 3D Printer Heated Bed Toughened Glass Clear Build Plate UK STOCK](http://www.ebay.co.uk/itm/300x200x3mm-3D-Printer-Heated-Bed-Toughened-Glass-Clear-Build-Plate-UK-STOCK-/302067007035).

To paraphrase, "Usually if things seem to good to be true, then they are probably fake." However, I wondered whether it was worth a punt as it is only £10, and then if I would be able to verify its veracity once it was in my hands.

**Tags:** build-plate

> **Comments:**
> **username_1**: Good question, I worked a while in labs. I think borosilicate glass was not looking greenish from the side (but I am not 100% sure). Other than that, the density is lower than of regular glass.  

---

## 4 answers

### Answer by username_8 on 2016-11-28. Score: 3 | Accepted answer

Google turned up this thread: <http://arstechnica.com/civis/viewtopic.php?t=96214>

There don't seem to be any easy, definitive tests. You have two main options, both of which seem to require a fairly high level of laboratory skill (but nothing fancy in terms of equipment).

The refractive index of Borosilicate glass is very similar to vegetable oil (implying no reflection from a boundary if you have a pool of oil on the glass).

The density of the glass can be measured too, using a water bath. This should also be able to give a fairly accurate answer.

Stress testing seems the most reliable way to determine if you have a 'good' sample, but may be more expensive.


---

### Answer by username_2 on 2018-10-10. Score: 2

All you have to do is submerge your sample of glass into mineral oil. If it seems to disappear, it's borosilicate.

> **Comments:**
> **username_0**: Hi and welcome to SE.3DP! Do you have a link, image or video to demonstrate this visual effect? In addition, please keep comments friendly... if you disagree with someone else's answer there is no need to denigrate it. You may also wish to edit your answer, and fix the typos. Thanks :-)  
> **username_3**: https://www.exploratorium.edu/snacks/disappearing-glass-rods  

---

### Answer by username_4 on 2023-11-28. Score: 1

Some more details about [a suggestion](https://3dprinting.stackexchange.com/questions/3098/how-can-i-determine-whether-my-borosilicate-glass-is-fake-or-not#comment11269_7157) made to the answer on [How can I determine whether my borosilicate glass is fake or not?](https://3dprinting.stackexchange.com/questions/3098/how-can-i-determine-whether-my-borosilicate-glass-is-fake-or-not/7157#7157).

Submerging the glass in mineral oil should make it disappear if it is borosilicate glass, as demonstrated below. This phenomenon is known as [the "index matching" effect](https://en.wikipedia.org/wiki/Index-matching_material). The index of refraction of borosilicate glass is n=1.47, and that of mineral oil is also around n=1.47, depending on the type of mineral oil used. However, as mentioned in [this comment](https://3dprinting.stackexchange.com/questions/3098/how-can-i-determine-whether-my-borosilicate-glass-is-fake-or-not/21693#comment40845_21693), other types of glass might have a similar or close refraction index, making it hard to distinguish borosilicate from non-borosilicate using this test alone.

> The borosilicate glass and the oil have roughly the same index of refraction. When this beaker is immersed into a container of oil, the beaker becomes invisible.

[![An animated GIF of a small beaker inside of a larger beaker and cooking oil being poured into the smaller beaker overflowing into the larger](https://i.sstatic.net/ol9f3.gif "An animated GIF of a small beaker inside of a larger beaker and cooking oil being poured into the smaller beaker overflowing into the larger")](https://i.sstatic.net/ol9f3.gif "An animated GIF of a small beaker inside of a larger beaker and cooking oil being poured into the smaller beaker overflowing into the larger")

Source: [The Disappearing Beaker Experiment](https://www.teachersource.com/product/the-disappearing-beaker)

> **Comments:**
> **username_5**: This is true for most glasses other than high index optical types.  Pyrex and window glass have nearly identical refractive index.  

---

### Answer by username_6 on 2018-10-15. Score: -4

> "toughened" glass,

Lead, cadmium and barium would have that effect. It goes without saying that you wouldn't want that kind of glass anywhere near your neighborhood.

Even those items that mention borosilicate glass in the product description may have never seen any boron.

Some studies have found that more than 90% of items sourced from China are fraudulently labeled. There is no enforcement.

While stats say nothing about any particular sample, I'd certainly keep them in mind.

> **Comments:**
> **username_7**: It might be worth sharing some of said studies - also while it says what else the glass could be, it dosen't really help OP with working out if its borosillicate glass.  
> **username_0**: Hi and welcome to SE.3DP. Can you provide links, sources to back up your claims? *It goes without saying that you wouldn't want that kind of glass anywhere near your neighborhood.* [Pyrex](https://en.wikipedia.org/wiki/Pyrex) will be found in your kitchen probably. *Some studies*... what studies? Do you have a link? Your answer would have more worth with sources. Thanks. Also, you aren't really answering my question, but rather questioning the morals behind Borosilicate. I just want to know how to check that it isn't just plain old vanilla glass.  

---

