Track crud......mystery solved?

[bertiedog]

Repeated as a new post after adding to posting about track woes, as it is really a separate issue.

 

 

I may may stumbled on another answer to an old Model Railway conundrum, where does the crud on the track come from?

 

I recently saw a demonstration of a very strange device advertised to remove toxins for the human body. You sit with the feet in a bath of plain tap water, insert the electrical device into the water, two electrodes, and hold an earth lead. The water turns very turgid over a few minutes, and the sellers of these devices call the brown waste liquid the toxins that have left the body via the skin. They even provide a chart of colours to match with different toxins from different human organs

 

Needless to say these devices are a total scam, they do nothing to the body whatsoever. Most seem to be of US "design", and Chinese made.

 

This can be shown by inserting the electrodes into tap water, without your feet and the water turns brown anyway, the colour seeming to come from nowhere. Gas also appears, hydrogen and oxygen, normal electrolysis.

 

It seems experts say the brown stain comes from the steel electrodes, basically iron oxide.The voltage is about 12 volts dc (no AC) in these devices. When the water evaporates it leaves a brown powder.

 

If AC voltage is applied to electrodes in water, then the alternating current constantly reverses the process, and no brown sludge is created.

 

Now thinking about this, and a couple of experiments, it looks like a similar process is at work in Model Railways. It can also explain why some people do not get the problem and why electronic track cleaners work.

 

I damped a section of Peco track, (the make is irrelevant), with a mist of water, and let it dry a bit, then dragged wires along the track with 12 volts connected. It was fed by a current limiting circuit to prevent shorts blowing things. After a few minutes a brown/black deposit began to appear on the surface, coming it seems from nowhere...............

 

Now I repeated with 12 AC and no crud appeared at all.

 

The general idea is that damp in the air allows the same electrolytic action to act in the same way as the Toxin scam does. The variation in the amount of crud is down to how dry the air is in the layout room.

 

Track cleaners use a high voltage high frequency AC signal added to the DC to run the motors and this must stop some of the electrolytic action, and helps break up the deposit on the track.

 

It may also explain why older half wave controllers and PWM controllers seem to keep the track cleaner, as the waveform acts a bit like AC. It cannot reverse the action like AC, but there appears to be a reduction.

 

I checked with an industrial chemist friend, as most of the track we use is nickel silver, or brass, rather than steel, and he pointed out it is probably the zinc content in both that is behind the oxide crud instead of the iron oxide with steel.

 

So it seems the answer is to restrict any damp near the track, or in the room or loft etc., not very easy frankly. Over the years, on reflection, the worst cases of crud on the tracks have been in sheds, where damp is obviously higher.

 

It also goes to help explain why some modellers swear that electronic track cleaners do nothing, the air in their room is already dry, and helps explain why results with such cleaners are at best variable.

 

So dehumidifiers and heaters may be part of the answer!!!

 

Stephen.

[Phil Bullock]

Or go DCC? :sungum:

 

Phil

[34theletterbetweenB&D]

Having had a full battery of physical characterisation lab kit available in the long ago, I put 'the crud' to the test. Nickel silver rail layout, mostly n/s or brass wheels, some plastic.

 

Metallic constituent: principally copper, present as copper oxide. Small percentage of other metals: lead, tin, iron and nickel, all as oxides.

 

The organic component was a mix of polymer species (matched the plastic wheels) and lubricant residue. My expert friend Dr Neelam Singh did all this as he had forgotten more about organic chemistry than I ever learned.

 

What I learned from this was to eliminate plastic wheels, and to be much more scrupulous in placing lubricant so that next to none could get onto wheeltreads and the rail head.

 

Regarding the very dominant presence of copper in the crud compared to the other metals, especially the nickel, I used a particularly whizzy XRD (in its day, we are talking 35 years ago) to look at the railhead of some well used rail, and also the underside of the same rail. The railhead surface was depleted of copper, compared to the underside, and indeed the bulk of the rail. So using the track changes the worked surface, accounting for why new track both dirts up faster, and then becomes both cleaner and with a better adhesion factor. Same applies to n/s tyres.

[Phil Bullock]

Have to agree with the "eliminate Plastic wheels" mantra

 

Best thing we ever did!

 

Phil

[bertiedog]

I am not surprised there are oxides of all the metals, there must be some ground off as wear as well.

 

The explanation about DC versa AC might also explain an odd comment many years ago at the MRC, that smaller end to end lines stay cleaner than large loop line layouts, where traffic tended to move in one direction. Constant reversal on a shelf layout reverses the polarity, and undoes the electrolytic action of the opposite movement, but longs runs in one direct build up the effect.

 

I am surprised that the rail shows depletion of most of the types of metal in the alloy, the zinc content would be the first to go, as with brass, where model loco fittings in brass on live steam boilers lose the zinc and then break up, all due to the slight electrolytic action between the brass and the copper boiler, aided by the heat.

 

Stephen.

[Matt]

I've also found one of the biggest sources of crud on my rails is from wheels of newly purchased stock. Previously I was placing anything new straight onto the track assuming all was clean... Not so. Everything now must be cleaned before first use - even factory fresh models including wagons and all. It does vary but I've seen brand new wagons turn a cotton bud black. Agree on sentiments around plastic wheels. And traction tyres too. M

[Graham456]

Have to agree with the "eliminate Plastic wheels" mantra

 

Best thing we ever did!

 

Phil

Hum but on the other hand ! Are plastic wheels cleaning your track for you, fit all your stock with plastic wheels and you won't have to clean your track, just grow long finger nails and sit in front of the TV watching crud whilst turning the wheels and running a nail to peel the crud off your wheels it used to get like traction tyres! there you go you can multi task?

( this is how I used to clean my triang wheels years ago)

 

More seriously this might explan why layouts need the track cleaning so much at shows, to many people breathing out damp air in the room

[Butler Henderson]

Agree with Matt, avoid traction tyres. After Warmingtons exhibition at York in 2014 I noticed a thin black deposit on most tracks but not those where the Q (Golden Arrow on the new Hornby 4F chassis, with much hacking away or the inside of the body and some significant chassis alterations) had been. It was the only loco in use with traction tyres and since then has had the traction tyre wheels replaced with plain ones. Just need to do with same with the Schools and T9 before they reappear on it.

[kevinlms]

Have to agree with the "eliminate Plastic wheels" mantra

 

Best thing we ever did!

 

Phil

The other thing is pick ups on more wheels. After all the 'crud' is often aided & abetted by arcing from poor contact.

[Gwiwer]

Dehumidifier?  Heaters?  

 

Has anyone told these people that my big layout is outdoors???

 

I agree with the fundamentals of what's been suggested.  I get more crud that I did before (and that was more than average because of being outside) since I disconnected the ultrasonic cleaners.  I only did that in order to run some locos with coreless motors but they don't need to be run outdoors and are intended for another project altogether.  I could refit the cleaning units.

 

As for getting into a bath with electrodes I'm pretty sure the "brown residue" which enters the water might emerge from a bodily orifice if there's any hint of electric shock!

[bertiedog]

 

As for getting into a bath with electrodes I'm pretty sure the "brown residue" which enters the water might emerge from a bodily orifice if there's any hint of electric shock!

The electrode detox scam foot bath devices seem safe, but, yes, a shock could cause issues in a bath. Amazingly a type of water heater from the past is being marketed by the Chinese, anode water heaters where mains is passed through the water to do the heating, It must be  AC to work properly with no crud. Used with care these devices work very efficiently, but they send chills down the spine of heath and safety people, and most electricians.

 

Of course I bought one off Ebay and now use it to boll water for coffee, but then I am a qualified electrician. The only Anode heaters I has seen before were large industrial boiler units, were efficiency is vital,

 

Stephen