Zamak Attack

[Showme]

   This car has never been on a layout but was not in its original Walthers humongous cardboard box. Those take up too much room for storage, so I toss those boxes and put Walthers cars in spare Atlas or MT boxes. All stored in the same low humidity, temperature-controlled year-round closet. All of its new brothers with it and it is the only bad one. Humidity might have a factor in the problem, but I suspect very minor.

Bob

[learmoia]

The Rivarossi Zinc rot started to spike in the mid-late 90s and early 2000s (about 25-30 years after release)..

The Walthers Coil Cars were made in the mid 1990s.. and it's... 2024........

[Showme]

  Speaking of dates and time, something I had forgotten about came to me. I have 4 of the Micro Trains boxcars that the floors swelled and exploded the shells. I'm not at home to look at the model numbers but they were released within the last 5-10 years so not that old. They are a modern style 50' boxcar that came with loads inside. MT did replace those for me with substitutes they had on hand. They got stuck with some bad alloy at one time.

Bob

[Doug G.]

If there is a Zamac problem, it usually presents itself well within a few years. A casting doesn't go years and years and then suddenly deteriorates.

Doug

[GGNInNScale]

Hi to all   Zamak is zinc and aluminum with a touch of magnesium and copper.  Aluminum is barely affected by moisture- it forms a protective layer and is relatively inert.  Zinc will oxidize ("rust") like iron does.  Magnesium and copper are between zinc and aluminum in reactivity to moisture.  The issue is that zinc oxide forms (yep, the stuff in sun blockers) swells and the frame becomes somewhat spongy.  This is the "rot" to which people refer.  A lot of the problem is the storage environment (moisture and temperature), but also on the quality of the initial mixture blending, and pour conditions at molding time.  If the mixture retains a good metal distribution it will be more resistive to rot.  If not, then you get the crumbles.

[jagged ben]

I have four Intermountain F units that sat stacked with each other on a shelf in their boxes for maybe 4 years.  One frame rotted and the others are all fine.  In fact it was just one half of the frame that rotted, the other half was ok.   Not to mention the dozens of other locos also stored in their boxes on the same shelf.   The conditions of storage are just not a factor in which ones rot and which don't.   Stop telling people that the conditions of storage have anything to do with whether (as opposed to perhaps how fast) it happens.  The storage environment is not a 'lot' of the problem, it is in fact almost zero percent of the problem.   (Barring, like, your stuff actually getting wet.)  The lack of quality control in the metal alloy purity is the problem.  It is essentially the entirely of the problem.  As Wikipedia says.

(Btw if anyone wants to know, I went to IM's 'Parts Request' page and requested new frame pieces and one spacer/coupler mount part.  Only got an auto-response by email.  Then about three weeks later a package shows up with an entire mechanism minus one truck.  Motor, worms, lightboard, etc.   YMMV.  This was all recently after they just shipped new ones for the first time in years, so I guess I got lucky.) 

[peteski]

   The conditions of storage are just not a factor in which ones rot and which don't.   Stop telling people that the conditions of storage have anything to do with whether (as opposed to perhaps how fast) it happens.  The storage environment is not a 'lot' of the problem, it is in fact almost zero percent of the problem. 

I wouldn't be so absolute about dismissing the storage conditions. You actually contradicted yourself by stating "(as opposed to perhaps how fast) it happens".  That will play a factor in how fast the inferior alloy will degrade.

[jagged ben]

I wouldn't be so absolute about dismissing the storage conditions. You actually contradicted yourself by stating "(as opposed to perhaps how fast) it happens".  That will play a factor in how fast the inferior alloy will degrade.

Perhaps.  As I said.  I'm rather doubtful about that though.  I'm also quite doubtful that zinc oxidation has anything to do with it, but decided not to get into that since I don't know for sure.  I suspect that temperature variation plays a bigger role than humidity.   If either really matter.

One thing's for sure, if humidity and zinc oxidation were the primary cause then I'd have had over a hundred loco frames rotted, not half a frame.

[tehachapifan]

It seems to be very common for folks to equate zinc pest with corrosion and assume that storage conditions must be the culprit. I think of it being more like weeds growing in the Spring. If the seeds are there, the weeds are going to grow anyway, but wet conditions may make them grow sooner and taller. in the case of zinc pest, the "seeds" are the contaminates in the alloy.

[brokemoto]

(Btw if anyone wants to know, I went to IM's 'Parts Request' page and requested new frame pieces and one spacer/coupler mount part.  Only got an auto-response by email.  Then about three weeks later a package shows up with an entire mechanism minus one truck.  Motor, worms, lightboard, etc.   YMMV.  This was all recently after they just shipped new ones for the first time in years, so I guess I got lucky.)

The guy on the other forum who brought the IM problem to the attention of many of us had something on the order of fifty locomotives explode, if not more.  He is a power collector.    When he told IM about the problem, they offered him replacement frame halves but he had to pay for them.  He considered that response to be somewhat less than satisfactory.

My guess is that one reason that IM would not do much for him was the numbers.  IM was not about to eat that expense for one person.  In quoted poster's case, it was one unit.  IM can afford to do something about that.

All who read this will do well to be aware that I neither damn nor defend  any party involved in this.  I simply state what occurred (to the best that I can remember) and offer my guesses as a possible explanation.

I did once have an unrelated  problem with a pair of IM units. An official of IM instructed me what to do.  I sent the items to IM, they fixed the problem and returned them to me, all free of charge. When I had a similar problem with another pair of units, I opened them up, found the problem, corrected it and informed IM.  IM did reply to me that it had just discovered the same culprit and was going to address the problem.  .The official informed me that he would not consider the warranty void i my case.  In short, the CS that I have received from IM always has been top-drawer.

[Showme]

   Off of the original subject just a little but I have kudos for IM. I lost one of the handrail medallions from one of my Santa Fe Bicentennial SD45-2's. I called IM and the gentleman I talked with said those were long gone. I was going to scan and print the medallion from the other side and glue it to a thin styrene dot for an acceptable replacement but lo and behold, an envelope with 3 of the originals arrived in the mail before I did that. The man didn't just drop it, he obviously searched until he found some.

Bob