Sciencemadness Discussion Board

Boiling Stones

JJay - 16-11-2015 at 22:10

It looks like teflon boiling stones are very expensive on online auction sites. I've heard of people using pieces of pottery or broken glass, and carbon boiling stones are available quite inexpensively, but I'd really prefer PTFE... are there any inexpensive ways to acquire PTFE boiling stones, or can I actually get by without them?

ganger631 - 16-11-2015 at 23:15

I have similar question regarding boil chip. However, i think teflon stir will work.

Deathunter88 - 16-11-2015 at 23:39

Quote: Originally posted by JJay  
It looks like teflon boiling stones are very expensive on online auction sites. I've heard of people using pieces of pottery or broken glass, and carbon boiling stones are available quite inexpensively, but I'd really prefer PTFE... are there any inexpensive ways to acquire PTFE boiling stones, or can I actually get by without them?


PTFE stir rods work beautifully as boiling stones. More reliable than pottery/broken glass, and reusable too. Also has the functionality of being a stir bar at the same time... (YAY my 100th post)

JJay - 17-11-2015 at 00:02

Can you actually use a stir bar as a substitute for boiling stones or is stirring necessary also? I usually prefer to use stirring, but sometimes I'd rather do without it....

[Edited on 17-11-2015 by JJay]

Deathunter88 - 17-11-2015 at 01:56

Quote: Originally posted by JJay  
Can you actually use a stir bar as a substitute for boiling stones or is stirring necessary also? I usually prefer to use stirring, but sometimes I'd rather do without it....

[Edited on 17-11-2015 by JJay]


You can use a stir bar purely as a boiling stone. In fact, any sizeable piece of PTFE will work. I sometimes use the stopcock of my broken buret as a boiling stone.

ave369 - 17-11-2015 at 07:09

I think porous boiling chips are better. With them, even concentrated sulfuric acid boils as calm as a chicken egg being boiled.

Deathunter88 - 17-11-2015 at 07:57

Quote: Originally posted by ave369  
I think porous boiling chips are better. With them, even concentrated sulfuric acid boils as calm as a chicken egg being boiled.


I have never had a need for boiling aid when boiling concentrated sulphuric acid, it just goes nice and smooth on it's own. I don't know why, maybe some contaminant in it?

ave369 - 17-11-2015 at 08:00

In my experience, sulfuric acid is always a tough customer when boiling. There were times when even diluted sulfuric acid bumped like gunfire: I was even afraid that my retort will explode.

Amos - 17-11-2015 at 08:29

Quote: Originally posted by ave369  
In my experience, sulfuric acid is always a tough customer when boiling. There were times when even diluted sulfuric acid bumped like gunfire: I was even afraid that my retort will explode.


I use pieces of clear natural quartz; I honestly think they're just about the best thing possible to use. They've never given me a problem even with concentrated sulfuric acid.