Sciencemadness Discussion Board

How does K2r work??

Quince - 24-9-2005 at 02:43

From the ingredients I found on the net, it's not clear to me how it works (pentane, hexane, heptane, and silica gel). When you spray it on, as the propellant evaporates it sort of grows out from the fabric surface about half of a millimeter into a white powdery texture, carrying some of the stain. So, how's it work?

neutrino - 24-9-2005 at 05:35

A silica gel aerosol? Strange.

My guess about how it works: the mixture of alkanes and silica is applied to the surface. The nonpolar alkanes absorb into the fabric and dissolve the stain, as dry cleaning solutions do. The stain solution on the surface (where the silica remained because it is a solid and thus cannot penetrate the fabric) evaporates, depositing the stain on the silica and, by capilary action, drawing more solution to evaporate until all of the liquid is gone.

That's my guess, anyway.

Quince - 24-9-2005 at 14:52

Is silica gel powder white? Whatever it is, getting the dry powder on one's hands you can feel the dehydration. Nasty stuff, especially if it gets in your breath...

praseodym - 25-9-2005 at 01:41

Yes, silica gel powder is white. Silica gel is normally made from sodium silicate, if I am not wrong. And we do know that most solid sodium salts are white.

unionised - 25-9-2005 at 03:50

Silica gel is made from sodium silicate but it is made of silica.
Silica is white.
Plenty of sodium salts are coloured, chromate, manganate etc.
Plenty of silicates are coloured too.

praseodym - 25-9-2005 at 22:50

Quote:
Originally posted by unionised
Plenty of sodium salts are coloured, chromate, manganate etc.

The colours in these sodium salts are attributed by the presence of the coloured anions. The sodium salts which I am talking about here are sodium salts coupled with anions that do not give a colour. That is why I said most sodium salts are white because the sodium salts I am talking about here are those without coloured anions, e.g. permanganates, dichromates, etc. Thanks for the clarification anyway, since I did not make my point very clear.

FrankRizzo - 26-9-2005 at 19:57

Sounds like it works via chromatography. The stain, assuming that it's soluble in the solvents, is carried up through the substrate.

Ingenious.

Quince - 14-1-2006 at 22:06

I ran out and now I can't seem to find it anywhere in Vancouver. Anyone in Canada have a couple of cans I can buy off them? I don't want to be importing from the US.

I tried using alcohol and talc, but it doesn't work nearly as well.

mick - 15-1-2006 at 07:54

You could try get some "water glass" which is sodium silicate solution (in the UK it is still sold and was used as an egg preservative). If I remember right add some acid and precipitate colloidal silica. Filter and dry. Outside, cover the stain with the silica and spray ligher fuel from the other side.

mick

Quince - 15-1-2006 at 11:13

For a moment there I thought you meant the liquid lighter fuel, rather than the butane. That would have been fun...