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View Full Version : Using Liquid Nitrogen in Modelling for Removing Paint and Putty



Spellscape
01-22-2013, 09:44 AM
Hi all

I've made this video just for fun. It was experiment

http://www.youtube.com/watch?v=gnNhk8BcyaQ

Verilance
01-22-2013, 06:59 PM
I really don't know why you even expected it to work ??? but interesting experiment I guess....

pseudodelic
09-16-2014, 03:26 PM
This is so dangerous. Most people think it is the coldness of the LN2 but it is the fact that it can fill 70 times the volume of liquid with gas and Nitrogen cannot be breathed and displaces the oxygen filled air. Doing this in a small room or a confined space could kill you. BEWARE!

Spellscape
09-16-2014, 03:33 PM
Nope - rember 80th music - most of nice "smoke on floor" was done using nitrogen.
But if you never used nitrogen before - just DON'T do this

daboarder
09-16-2014, 06:27 PM
This is so dangerous. Most people think it is the coldness of the LN2 but it is the fact that it can fill 70 times the volume of liquid with gas and Nitrogen cannot be breathed and displaces the oxygen filled air. Doing this in a small room or a confined space could kill you. BEWARE!

Yup, pushes the oxygen right out of your lungs in no time

- - - Updated - - -


Nope - rember 80th music - most of nice "smoke on floor" was done using nitrogen.
But if you never used nitrogen before - just DON'T do this
Dude, seriously....dont argue with the chemists on this one

http://en.wikipedia.org/wiki/Expansion_ratio\

smoke on the floor is usually done by placing dry ice (carbon dioxide) in water, not liquid nitrogen.....

40kGamer
09-16-2014, 09:49 PM
Dude, seriously....dont argue with the chemists on this one

http://en.wikipedia.org/wiki/Expansion_ratio\

smoke on the floor is usually done by placing dry ice (carbon dioxide) in water, not liquid nitrogen.....

Arguing with a chemist is a good way to win a Darwin award!

Vanadius
09-17-2014, 02:19 AM
I registered just to respond to this, guys :D

78% of the air is nitrogen so its not poisonous to breathe in the fumes because you are already breathing it. Since it's really hard to breathe in liquids as well you need not worry about expansion ratio unless you are sitting in a 1m^3 airtight cube doing this (which would just raise further questions from my side) It's just going to get warmer as a gas which doesn't make up that much volume change as it expands. Even if you would breathe in less than the 21% oxygen the air usually has, it wouldn't be a problem because you don't use all of it anyway. Remember, when you perform CPR you are effectively exhaling into someone else which still has enough oxygen content to supply another persons lungs. So don't be scared about it. There is even an ice bucket challenge where someone pours liquid nitrogen over his (hairy) head. I probably wouldn't do that but there is imho nothing very dangerous about it. short gif of the challenge (http://i.kinja-img.com/gawker-media/image/upload/s--D6Tqzehk--/c_fit,fl_progressive,q_80,w_636/tegqtkxnksclan9fq5zu.gif) Just don't hold your finger in it ;)

This stuff is -196°C when liquid so the experiment was interesting because _rapidly_ cooling the putty might have warped it so much that it would have popped right off. Metal is a good thermal conductor so putting liquid nitrogen on it may have cooled it even faster which prevented that. Thanks for trying it out so I don't have to :D

CoffeeGrunt
09-17-2014, 03:42 AM
It's okay to breathe air with a lower than 21% Oxygen ratio, because Altitude Sickness is not a thing that kills people due to a lower amount of Oxygen, (though this is due to a lower amount of air in general, it still represents less O2 getting pumped into your lungs with each breath.)

That aside, you clearly didn't die and the video was entertaining. I'd say put a, "Don't Try This at Home," disclaimer on it, but it's unlikely Little Timmy's going to crack open his mum's Liquid Nitro supply and start pouring it on his Ultramarines.

daboarder
09-17-2014, 04:23 AM
Ahhh it funny to see people argue with a chemist,just so much fail.

1) No one said that N2 is toxic, its not, heres the MSDS
http://www.liquidnitrogenservices.com.au/safety/ln2_msds_e1.pdf

2) Yeah so you can survive on 20% oxygen.....thats not what we're talking about, when we say that liquid nitrogen displaces oxygen, we mean ALL of it.

That expansion ratio means that for every 1 L of liquid nitrogen that boils off, you create roughly 700 L of N2.....dont be stupid people

And hell, this isn't even touching on the fact that volumes of liquid nitrogen can cause the oxygen in the air itself to condense, forming liquid oxygen...something you DON'T wan't to happen (extremely flammable)


First aid measures
- Inhalation : In high concentrations may cause asphyxiation. Symptoms may
include loss of mobility/consciousness. Victim may not be aware
of asphyxiation.
Remove victim to uncontaminated area wearing self contained
Breathing apparatus. Keep victim warm and rested. Call a doctor.
Apply artificial respiration if breathing stopped.
- Skin/eye contact : Immediately flush eyes thoroughly with water for at least
15 minutes.
In case of frostbite spray with water for at least 15 minutes. Apply
a sterile dressing. Obtain medical assistance.
- Ingestion : Ingestion is not considered a potential route of exposure.


So yeah....arguing with chemists and all that.

I really cannot in good conscience EVER suggest using liquid nitrogen to clean a model when far less dangerous materials are readily available.

Wolfshade
09-17-2014, 04:26 AM
Silly chemist with their smells and colours...

daboarder
09-17-2014, 04:32 AM
Silly chemist with their smells and colours...

and cancer and things like that....



Seriously, you don't even want to KNOW about HF

Mr Mystery
09-17-2014, 05:12 AM
I like heliums.

It makes your voice all squeaky.

Wolfshade
09-17-2014, 05:39 AM
and cancer and things like that....



Seriously, you don't even want to KNOW about HF

[Brian Cox]It's all just a proxy for Physics.. :)[/Brian Cox]

Morgrim
09-17-2014, 05:55 AM
Seriously, you don't even want to KNOW about HFHey now, a chemical that can dissolve your bones without burning your skin and requires the antidote to be applied within 15 seconds is very grimdark.

Kibbles Lil-Bit
09-17-2014, 06:34 AM
I am just curious as to how many people actually have a handy flask of Liquid Nitrogen just happily lying about the house.

Vanadius
09-17-2014, 07:10 AM
We are not arguing because there already is only one prevalent opinion. You are trying to make your arguments more important by using your occupation as a reason and telling others that they therefore fail their reasoning. Which is unnecessary because we already agreed. In response to OP: There still are Clubs that use LN2 systems for smoke creation.

daboarder
09-17-2014, 07:01 PM
sorry, when someone starts talking about the toxicity of an asphyxiant and rambling about the expansion ratio of a liquid boiling to a gas as if they don't understand diffusion or molar heat capacity (or hell even the basics of what cryogenic liquids do to cells) then I kinda assume they have no idea what they are talking about.....because they don't.

and yes I have seen that liquid nitrogen ice bucket challenge and the man is an idiot.

Wizzardx3
09-17-2014, 10:40 PM
Chemist here as well. I wanted to discuss what the OP was trying to do with this experiment.
Materials change sizes slightly when their temperature changes. Different substances grown and shrink different amounts when undergoing those temperature changes. Some materials become brittle (most people have seen what happens to a racquetball in liquid nitrogen). In either case, it is possible that the paint or putty would come loose from the model under extreme temperatures.

Some interesting facts... the molds for making metal miniatures have a 'shrinkage factor' built in... something around 1-2% per linear dimension for most metals.

Now on safety... always read the MSDS and take appropriate precautions. Interesting experiment, but it does prove that there are better ways of going about this task.