7

I've been waxing my road and mountain bike chains for a few years now, and have always used just paraffin wax. Typically, I leave the leftover melted wax in the heating element (an old slow cooker) for use the next time, so the wax that's in there now has been heated up and cooled off several times now.

I've noticed that early on when the chain had cooled off it was incredibly stiff with wax, whereas now it's still stiff but much less so. I'm wondering if the age or constant heating/cooling of the wax is producing a worse/different lubrication.

Should I completely replace the wax every time, or just more frequently, instead of repeatedly re-using it?

  • Have you empirically observed chains lasting less long as the wax is reused? I suspect even if the wax is degrading, its not going to be all that significant in the amount of chains you use over your lifetime. – Batman Jul 14 '17 at 15:22
  • I have somewhat though measurements aren't precise. The first time on my road chain (new wax, new chain) lasted well over 1000 miles. The latest time (used wax, used chain), where the chain was never used in wet conditions, lasted for about 500-750 miles before I noticed typical chain noise indicating a need for lubrication. – Patrick Quirk Jul 14 '17 at 15:32
  • How are you cleaning your chain before waxing? If there are solvents left on the chain they could break down the paraffin over time. – Rider_X Jul 14 '17 at 16:11
  • @Rider_X I rinse with mineral spirits until the spirits come back clear, then rinse with denatured alcohol, air dry, then into the wax. – Patrick Quirk Jul 14 '17 at 16:18
  • @PatrickQuirk protocol sound right. Out of curiosity how many times have you re-heated the paraffin? I have just started waxing chains so this is thread is useful! – Rider_X Jul 14 '17 at 17:27
12

Paraffin wax is not a single chemical, rather it is a mix of alkanes with the formula CnH2n+2, having between 20 and 40 Carbon atoms. Commercially available Paraffin wax may also contain additives to raise melting point (normally 37 °C, 99 °F) or reduce brittleness (often stearic acid as found in tallow).

It's possible that when you immerse your chain, the longer alkanes are more likely to be retained in the chain. The stearic acid molecule (C17H35CO2H) is only 18 Carbon atoms long, but the O and OH groups may increase the chances of it adhering to a surface.

Alkane cracking might also be occurring, catalysed by some impurity in the pan or chain, breaking the longer molecules up into shorter alkanes. Paraffin's density should be about 0.9g per ml. Alkanes from C5-C16 (inc octane, decane) are liquid at 20 °C with density 0.63 to 0.77 g/ml. The shortest Alkanes are gases: Methane, Ethane, Propane, Butane. With an accurate scale you may be able to detect a difference in volume between your used wax and the same volume of fresh wax.

  • Whew, more chemistry than I was expecting on this sub. Next time I get it warmed up, I'll see if I can weigh and measure volume of the wax to determine if density is indeed decreasing. If so, and if I understand you correctly, that indicates fewer long alkanes which could mean less wax retained in the chain, making older wax less effective than newer wax. Correct? – Patrick Quirk Jul 14 '17 at 15:20
  • Yes, and the tolerances in a worn chain will be wider, so the range of alkanes lengths retained would be higher than in a brand new chain. You could use your thinner wax for new chains and mix in more fresh wax as the chain ages... – Emyr Jul 14 '17 at 15:25
  • I don't believe there will be preferential adhesion for the longer chain molecules - since the paraffin is well mixed, and viscosity means there is not just a monolayer of molecules transferred to the chain. Chemical degradation is more likely to be the cause. It would be interesting to measure the change in density - which according to your numbers would be surprisingly large. – Floris Jul 14 '17 at 20:01
  • For chains though, it's not the surface adhesion that matters, it's getting the lubricant into the space between the pin/outer-plate and the inside of the roller where the the inner plates deform inwards. You need capillary action to draw the lubricant in and for it to stay when you cool and dry it. – Emyr Jul 14 '17 at 20:10
  • Note also that the crystallization temperature of the longer chains is higher than that of the shorter chains, so they may preferentially crystallize onto a cold chain first. – Warren Dew Jul 15 '17 at 1:42

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.