Mmmmmm , interesting. I had made a aluminium bolt (6061 T6 Aluminium) years ago and ended up with a spare. So I figured I would be careful and wrap it in electrical tape keeping it nice and safe. 30 years later I opened it up and where ever the adhesive touched it had pin holes ....... presumably a reaction between the 6061 and adhesive. The metal had never come in contact with anything else. I'm still drawn to think about the Intermountain loco problems. IM locos here in Australia seem to suffer more from loose bodies on chassis , , never swollen. I have not met anyone with IM zinc rot here. Zinc rot, while quite real, doesn't seem to get triggered here. Generally Australia has a warm & quite humid climate.
It is not humid here in Sacramento, but it does get hot in the summer and cold, no snow, in the winter. All of my locomotives were kept in their cases and in a box inside the house. So it is not like they are subjected to humidity or wild temperature swings. For whatever reason, some of the frames are chemically unstable. I have a DRGW FT that I found yesterday, put it on the track and it ran a little sluggish. Then I tried to remove the shell and it was not possible, the swelling has started and there is nothing that can be done about it.The corresponding B unit was the same way. So it goes to show, at least for me, to never trust an IM locomotive, so no more purchases, no more testing no more anything with IM locomotives. Even the one frame they replaced in an SD40T was 1/2 inch too short for the shell, making the locomotive still unuseable. Just a note, adhesives can be acidic depending on what they need to adhere to.
That's interesting. I live in Houston, which is also pretty warm and very humid, and I haven't suffered any zinc rot in any of my 30+ IM locomotives. I seem to think that there is some external factor at play here that we just haven't figured out yet.
Maybe being humid retards the zinc rot...gets humid here in Minnesota and I only had a problem with one F3.....He said not humid at his place and all kinds of zinc rot....make you think...I don't store any of my engines...they sit on shelves in the open when not being used.....
For what it's worth, Wikipedia has an article on Zinc Pest that states that high humidity (above 65%) accelerates the degradation process. Zinc Pest is caused by lead (Pb) impurities in zinc (and/or Zamak alloy) metal. It is also very likely that various batches of zinc have different levels of Pb impurity, and thus differing ZP susceptibility. Thus some batches of locomotives will similarly have different occurrences of zinc pest than others. If lead impurities are not tested, they cannot be controlled for uniform presence either. It is frustrating that Zinc Pest was apparently eradicated in established industrialized nations several decades ago, but continues to pop up in "new" 3rd world sources. The never-ending chase for profit, and tightening environmental controls, leads to new/cheaper material and casting sources that seem to have to learn this painful lesson all over again, for themselves and their customers.
This is getting really interesting, I wonder if we stored our IM FT's, F3's and F7's a bit differently. I am thinking about taking all the shells off their mechanisms and storing them separately so if zinc pest takes hold I will still have the shells intact. Also thinking way outside the box, if the loco's are still intact I wonder if storing them in a fridge might slow down the. chemical reaction between the zinc and the lead impurity. I've seen a claim that every 10 degrees in temperature accelerates the chemical reaction. I also wonder if it's time that MT seizes an opportunity and increases it's runs of FT AB sets to offset IM's crumbling models
I also had some MTL boxcars with the zinc pest. I bought 5 undec 50' ribside cars about 2 or 3 years ago. I got them out to run at a show in Dec of 2021 and the shells were bowed and the sill had broken under the door. I emailed MTL a couple of times but never heard back. I mentioned it to the owner of my local shop and he contacted MTL. They sent 5 replacement frames that included trucks, the underframe deail piece, and body mount couplers. I was able to glue the sills back together so the new frames would fit tight enough not to fall out when handled. I'm not happy with the time it took to get the replacements, but they did eventually sent replacements. I had told the shop owner that I didn't need new shells, as I was happy with the paint, decalling, and weathering on the originals, and they were easily fixed. The undec cars that had the issues were molded in a blueish green plastic. Thanks, Mike
I'll keep mine in the warmish, humid air here as a test for these conditions. . It didn't get that hot today but I didn't bother looking at the temp after it climbed past 40C yesterday. I have 6 IM tunnel motors and 4 Micro Trains FT's ........ all good so far, fingers crossed.
I have no reason to doubt what's written in Wikipedia. Its not a scientific journal article but it will steer us in the right direction. Is it possible to test a failed chassis to see exactly what is the affected metal? .... the horse has already bolted as they say but it would be interesting to know. I don't think Micro Trains or Intermountain would knowingly do something to their zinc mix to cut corners. It is possibly something no one expects .....ummmmm ........... new tools used in the melting and moulding process ???? .......
It all boils down to a lack of Quality Control. Unfortunately, Intermountain has to rely on the Chinese factory, so they have no real control it seems. The Chinese are known for taking whatever shortcuts that will increase profits. In fact in many cases they have delivered baby toys with lead paint and other poisonous finishes until the government here stopped the imports. It seems Atlas has a better relationship with their manufacturer, or at least a better quality control system. I am sure if Intermountain decided to enforce quality standards that these issues would not be happening. I am not sure if they know what they are doing with their Chinese partners. IM has dug a deep hole of incompetence, and until they climb out these issues will continue.
Zinc pest, or zinc rot, is due to a corrosion process between the zinc crystals caused/accelerated by the presence of lead impurities. Corrosion is an oxidation process (like rust*), so oxygen is also required. Metallic oxidation is accelerated by the presence of water (including water vapor) and heat. Therefore, you should be able to delay/slow ZP if you put (and periodically refresh) a desiccant packet in the plastic storage box with the locomotive. You probably do not want to "store" your susceptible locomotives on your layout or display them on open shelving (unless in their cases with desiccant) especially if your layout is in a humid location. Storing your locomotives in the freezer would likely delay the onset/progress of ZP, but you would need to raise the locomotives' temperature in a dry environment (LOW temperature oven or desiccant box) when they are removed from the freezer, until they reach room temperature. *Zinc itself does oxidize, but at ~1/60th the rate of steel. Galvanized iron/steel is essentially zinc plated iron/steel. Furthermore, the zinc oxidation chemically suppresses oxidation of the underlying iron. Thus galvanization with zinc is one of the most cost-effective corrosion preventatives for iron/steel. Galvanized steel is much cheaper than stainless steels, but not as effective. Stainless steels are alloys of iron, chromium, nickel and molybdenum in several different ratios for different levels of strength and/or corrosion resistance. Like my father (a chemical engineer) told me, there are many grades of stainless steel, some much more corrosion resistant (and more expensive) than others, along with variations in other qualities. He saw chemical tanks corroded through (typically at the "water" line where the liquid met the "air"), made of stainless steel that would likely last centuries in household applications.
I was able to buy a pair of MTL C of G boxcars to replace my zinc pest damaged units after contacting the seller and asking that he inspect the potential replacements for visible signs of damage. When he proclaimed them to be “good to go”, I purchased them, and closely inspected them myself once they arrived. While the bodies were not yet cracked and destroyed, close inspection revealed that the frames were beginning to swell slightly, and the ends of the bodies were beginning to curve outward due to the pressure. One truck pin and truck were already loose as well. I was able to remove the shells (although with great difficulty) without major damage, but that means that my experience with these cars has been that 100% of them have shown zinc pest deformation of the frames. Also, I still have had no response to my multiple eMails to MTL concerning this issue. Until I hear from them, I will not be purchasing any new MTL cars. They are far too expensive for me to be able to afford to play Russian roulette with their zinc frames.
Precisely the reason I stopped buying anything but decoders. I have yet to get to all the freight and passenger cars. I am pretty sure since all my passenger cars are Kato, that they will be OK. Lead and Dead seems to be the case when QA control is missing.
@railtwister Did you note @Joe D'Amato from Micro Trains responding a couple of days ago in this thread? Has he responded to any communication from you?
I've not gotten any messages, but the front office did respond to his first email and again when I saw his post. We also issued a voucher to compensate the loss when we first got the email. I'm posting this here in case he is having/or we are having connecting via email....it happens. IF he contacts the front office they can walk him through using the voucher. Joe
Sorry, bad metal is a factory quality control issue, and should not need a warranty to be replaced at no charge by the factory. Something made of metal should not ever self destruct on its own, no matter how old it might be! SHAME on Intermountain!!!
It depends on who sourced the bad zinc ore, not necessarily the factory that cast the frames, or the factory that assembled into the frames into the final product. But ultimately, it is Intermountain's product, and their responsibility.
