I thought I’d post some info about chain cleaning here rather than in the Gravel Waxing thread.
A bit of background: Whilst developing my hard wax chain lube I used lab glassware so I could observe its behaviour during melting / solidification cycles. This meant I then had to clean the wax off the glassware and this proved to be more difficult than expected, every standard cleaning regime left a film of wax on the glass. This is apparently because when solid, waxes are effectively insoluble even in the most suitable solvents because there is not enough entropy available to overcome the enthalpy of fusion*.
An illustration of this point: here’s a pic of a flake of Carnauba wax suspended in a 55 : 35 : 10 mix of xylene, hexane and citrus terpene after half an hour on a magnetic stirrer. This solvent mix is as close to the ideal solvent for Carnauba as I could make, the distance in Hansen space being a little under 0.3 Mpa^1/2, well inside Durkee’s maximal distance for solvent cleaning (Ref Durkee, Cleaning with Solvents: Science and Technology, Elsevier 2013).
The wax is yellow, the solvent is clear. If the solvent were working, it would be yellow with dissolved wax.
The boiling water trick doesn’t work well either: water and wax don’t mix.
Here’s a beaker in which I melted some of my hard chain wax then poured it out, leaving residue on the bottom and sides:
I then boiled water in the beaker for five minutes after which the beaker looked fairly clean with a scum of wax on the surface. Removing the wax and the boiling water however revealed a skin of adherent wax on the bottomof the beaker: sorry for the dreadful pic the camera battery was running low.
This makes sense: water is a very poor solvent for wax (distance in Hansen space is about 40 MPa^1/2) and wets the surface less well than does the wax, so it is not energetically favourable for the water to displace the wax.
So if solvents don’t work and heat doesn’t work, what does?
As I mentioned above, solvents don’t work because the available entropy is not enough to overcome the enthalpy of fusion. The answer is to get over that hump and then dissolve the melted wax. That requires a solvent that can safely be used above the melting point of the wax, stays liquid when cooled and can be washed out by ordinary means. I use the degreaser/ wax remover I developed, it and my wax blend have a distance in Hansen space of about 1 MPa^1/2 and it is stable up to quite high temperatures.
I remelted more wax in the beaker above (to make the comparison fair) then heated my degreaser in it for two minutes, followed by five minutes in ethanol in the ultrasonic bath:
I left the pour mark alone so you’d know I wasn’t cheating and substituting a different beaker.
- Or is it the enthalpy of crystallisation? I’m really not sure.