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Offline Dave  
#1 Posted : 07 December 2004 21:25:38(UTC)
Dave


Joined: 22/08/2004(UTC)
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Is there any way to stop Zinc Rot or Zinc Pest ?

Dave

Offline Dave  
#2 Posted : 07 December 2004 21:32:23(UTC)
Dave


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Forgot the picture

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Offline laalves  
#3 Posted : 07 December 2004 22:19:29(UTC)
laalves


Joined: 10/02/2004(UTC)
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Man.... is that serious. Never seen something so serious. First question: do you store your oldies in the original white-styrofoam packages? If you do, stop doing so. Styrofoam atacks zinc over the years.

To stop the process, you have to deny access to oxygen, since this is an oxidation process. You can use some sort of anti-corrosion primer, after you remove as much of the corroded zinc as you can. Suggest a grinder attachment to your Dremel or Proxxon to remove the corrosion.

After the primer, spray it all black again, and cover with real coal.

You can always bragg that you did an upgrade of your oldie with real coal, for added realism....

Good luck!

Luis
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Offline Dave  
#4 Posted : 08 December 2004 04:19:52(UTC)
Dave


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Styrofoam ? These things came in cardboard boxes biggrin. Styrofoam was not used by Marklin for another 20 or so years. But, thanks for the help. I have a Dremel cordless and will start with a brush to take off the oxididation.

Anyone else have thoughts or solutions ?

Dave
Offline xxup  
#5 Posted : 08 December 2004 10:06:11(UTC)
xxup

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Make sure that you use the Nylon brush - the brass may cause even more long term damage... I wonder what the chemical really is? Zinc Oxide... What could disolve that without affecting the metal? There must be something out there...
Adrian
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Offline nico van zon  
#6 Posted : 08 December 2004 12:09:42(UTC)
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What is going on is not zinc rot, but a phenomenon that's known as tin pest. The cause is a wrong mixture of the alloy. Under certain circumstanes this causes a change in crystalline structure of the tin. One of the circumstances is low temperature, so one measure to prevent this problem, or at least to slow it down, is to keep your models at room temperature.
Search on google for tin pest and you will find lots of sites that deal with this problem.
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Offline Thanos  
#7 Posted : 08 December 2004 13:43:26(UTC)
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Tin pest... Didn't know about tin pest...
This site is an MRR encyclopedia!
Thanos



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Offline xxup  
#8 Posted : 08 December 2004 14:01:11(UTC)
xxup

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Interesting reading.. Looks like the highest priority is to get rid of the crystalised material as it acts as a catalyst for further corrosion... See http://www.finishing.com/188/49.html

Scary stuff...
Adrian
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Offline Guus  
#9 Posted : 08 December 2004 16:18:40(UTC)
Guus

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Hi all,

In addition to what Nico already explained I may add that I've read that locomotives made in the years shortly after the war are the ones that are mostly affected.There was a shortage of the proper alloys so the quality of the material was not always up to standard.
Hope this will put your minds at ease a little biggrin.

Best Regards
Guus

post scriptum: I owe you all a reference to the article in which I found above mentioned information.I'm searching the Web and my desk[xx(][xx(].
Keep you posted Smile
Kind regards,
Guus
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Offline laalves  
#10 Posted : 08 December 2004 17:59:49(UTC)
laalves


Joined: 10/02/2004(UTC)
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Quote:
[size=1" face="Verdana" id="quote]quote:Originally posted by laalves
<br />Styrofoam atacks zinc over the years.


Well, this is what I saw in a cable documentary (I believe in the Odissey channel) where a die cast car collector was explaining this styrofoam related problem.

Anyway, in the 3097 BR23 restoration I finished a few days ago, of which I posted a picture in the Collector's Corner topic, I did what I explained above to remove the crystalized deposits.

To remove the larger deposits, I used a brass wire rotary brush. Then I went to manual removal with an old X-Acto blade and sandpaper. Then I picked up the Dremel again with felt rotary polishing tool.

Then I airbrushed it with dilluted Gunze Sangyo Surfacer grade 1000 and brush-used some grade 500 in places to fill in the roughness. Then I sanded it all flat (the main affected area was the top of the cab and some of the boiler top) and painted with Revell no7 gloss black enamel.

Let it cure for 3 days and applied a 30/70 mix of Xtracolor gloss varnish/Modelmaster flatcote. I obtained a nice satin sheen that looks like the original.

Only time will tell if the pest will surface again or not.

I went through the finishing.com link mentioned above and think that the problem therein mentioned is that of unpainted tin plates and other tin collector/antique items.

I believe the roting lok problem may be alleviated through the use of thicker coats of paint than Märklin used. From what I've seen in old loks, the paint job looks like a very thin coat of cellulose based paint. This wears out over the years and exposes the alloy to air.

I think that a thicker coat of paint may help a great deal in stopping the phaenomenon. I read somewhere that today's loks are painted with resin based paints and the painting process even involves oven baking, but I haven't seen any confirmation of this. Being true, this should be a very resistant coat.

Luis
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Offline Guus  
#11 Posted : 08 December 2004 22:11:43(UTC)
Guus

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Bon dia Luis,

Thank you for your detailed description of a cure for the problem.This is one of the reasons I like this Forum so much.

Best Regards
Guus
Kind regards,
Guus
Offline perz  
#12 Posted : 08 December 2004 22:28:35(UTC)
perz

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Quote:
[size=1" face="Verdana" id="quote]quote: What is going on is not zinc rot, but a phenomenon that's known as tin pest.


No, I don't think so. Tin pest affects things made of tin (and sometimes alloys containing a large portion of tin, like solder). Tin pest is caused by low temperature, since the stable crystalline structure of tin is different below 18 C than above 18 C. For tin alloys like e.g. solder the critical temperature is much lower (below 0 C).

The Märklin locos are made of zink alloy, with no or very little tin. One of the causes is a wrong mixture of the alloy, as Nico says, but it still isn't tin pest and the temperature is probably less important.
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Offline Webmaster  
#13 Posted : 08 December 2004 22:30:58(UTC)
Webmaster


Joined: 25/07/2001(UTC)
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2 years ago, we had this short thread about "Zink Pest"
https://www.marklin-user...fault.aspx?g=posts&t=347
Juhan - "Webmaster", at your service...
He who asks a question is a fool for five minutes. He who does not ask a question remains a fool forever. [Old Chinese Proverb]
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Offline xxup  
#14 Posted : 09 December 2004 00:55:44(UTC)
xxup

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Doomed - does not sound good.. [:(] Still it seems better to scrub it out (with the brass one) and seal with the clear varnish as Luis says in his posting.. Gasp - such a small thing . Imagine if we had these problems with real bridges...
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Offline Webmaster  
#15 Posted : 09 December 2004 01:14:48(UTC)
Webmaster


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Doomed... The process will go on, but at a much slower rate if it is sealed according to the instructions by Luis.
In 20 years or so, you *will* see the problem again...[:(]

Similar problems do indeed occur with concrete bridges standing in salt water....
Salt crystalizes and expands inside the concrete, making it brittle...
Very much the same basic phenomenon...

Rust on iron bridges is much easier to handle since it attacks from outside...
Zamac-pest and saltwater/concrete are attacks from the inside...
Juhan - "Webmaster", at your service...
He who asks a question is a fool for five minutes. He who does not ask a question remains a fool forever. [Old Chinese Proverb]
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Offline john black  
#16 Posted : 09 December 2004 14:25:23(UTC)
john black

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Quote:
[size=1" face="Verdana" id="quote]quote:Originally posted by Webmaster
<br />Doomed ... The process will go on, but at a much slower rate


Yes, in Klaus Eckert's "Das grosse Handbuch MÄRKLIN HO" there's one full chapter about it ... "Nope", he writes, "once it's inside that shell is rotting away" [xx(]

John

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Offline Guus  
#17 Posted : 09 December 2004 16:17:10(UTC)
Guus

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Hi all,

Here's a link to a Website that deals with ZinkPest I came across.Regretably in German only [:I].

http://www.tischeisenbahn.de/Restauri/page4.htm

Best Regards
Guus
Kind regards,
Guus
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Offline Peter Neumann  
#18 Posted : 10 December 2004 05:50:03(UTC)
Peter Neumann

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Joined: 18/12/2002(UTC)
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Location: Fort Wayne, Indiana
The cause of the zink pest / tin pest is accurately described by Guus. Luis's recommendations earlier are EXACTLY the right steps to take to atleast improve the appearance. I have done this several times on - particularly - old 809 metal coal tenders (ie G800, F800, GN800) with excellent results, i.e. no more evidence of corrosion.

Peter Neumann
Florida
Offline perz  
#19 Posted : 10 December 2004 10:16:15(UTC)
perz

Sweden   
Joined: 12/01/2002(UTC)
Posts: 2,578
Location: Sweden
Quote:
[size=1" face="Verdana" id="quote]quote:zink pest / tin pest

Do I have to say it again ? Zink pest is not tin pest. They are two different phenomenons with completely different physical mechanisms. Tin pest is not applicable at all since train models are not made of tin.

Anyway, I assume Guus' advices are appropriate for zink pest rather than tin pest.
Offline Guus  
#20 Posted : 10 December 2004 12:36:41(UTC)
Guus

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Posts: 2,616
Hi all,

I agree with you Per the name of the problem is Zinc Pest or Zinc Rot if you like.The way I understand it ,is that the material used in manufacturing the locomotives is called Zamac,which is an alloy of mainly Zn (zinc) and in addition Al (aluminium) Cu (copper) and Mg (magnesium).Inevitable there will be some other elements like Fe (iron) Pb (lead)and here she comes wink Sn (tin),which are seen as contaminants and their share must be kept as low as possible.
Might be that the latter gives some confusion in naming this phenomenon.
It's a long time ago I had training in Mechanical Engineering and I must stress that I only express my vision in this topic and it's in no way academically verified to be correct.

Just kidding biggrinbiggrin: Märklin has found the definite solution of keeping locomotives in top condition forever.You all know her: A platinum crococodile with ruby eyes made in 2000.

<hr noshade size="1]
originally posted by John:

Yes, in Klaus Eckert's "Das grosse Handbuch MÄRKLIN HO" there's one full chapter about it ...
<hr noshade size="1]

Thanks John for recommending this book in another topic.it's a gem biggrin.

Best Regards
Guus
Kind regards,
Guus
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Offline stenscience  
#21 Posted : 11 December 2004 00:52:47(UTC)
stenscience


Joined: 18/09/2004(UTC)
Posts: 789
Location: Santa Fe, New Mexico
I agree that the problem is likely to be Zn pest rather that Sn pest for the reasons stated above. Further, SnO2 (can't figure out how to insert subscript in this format) tends to form more rutile, elongate crytals than Zn oxide.
I was intrigued by the observation that the tender well appears to be most significantly affected by the oxidation. If there were some type of load in the tender that was laquered, or if the well itself were laquered, then the interaction of some types of these organic coatings with oxygen may have produced acetic acid, which may have accelerated the problem in that area. If so, then an aggressive debriding may be neccessary. If you do not wish to repaint (some old models may lose value when doing so) you might wish to seal the surface with some type of wax.
Although styrofoam was not used as original packing, if it was packed along with more modern models, or if Styro 'peanuts' were around, I believe that they can, over time, release some organic acids.
Please take this with a grain of salt, I am making suggestions based on my knowledge of science, not M* models.
Offline john black  
#22 Posted : 11 December 2004 16:49:05(UTC)
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Quote:
[size=1" face="Verdana" id="quote]quote:Originally posted by stenscience
<br />If you do not wish to repaint (some old models may lose value when doing so)


George, thanks for that scientific point of view - now even I can see the "chemical picture" Smile
Regarding value I guess there's nothing lost when painting a rotten and "restorated" loco. Since it's pested, anyway - all substantial collector value is already down the river ... biggrin

Best Regards
John

I hope no one visits a poor Southener's layout in Brooklyn. Intruders beware of Gators.
AT&SF, D&RGW, T&P, SP, WP, UP, BN, NYC, ARR, epI-III - analog & digital Marklin Classics only.
CU#6021 FX-MOTOROLA DIGITAL SYSTEM. Fast as lightning and no trouble. What else ...
Outlaw Member of BIG JUHAN's OUTSIDER CLUB. With the most members, worldwide

Offline Peter Neumann  
#23 Posted : 14 December 2004 05:35:55(UTC)
Peter Neumann

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Joined: 18/12/2002(UTC)
Posts: 251
Location: Fort Wayne, Indiana
Yes, one and all, it is ZINC pest, NOT tin (I merely referred to tin in response to an earlier message that mentioned it). George asked if this is particula to the tenders...and it would appear to be the case. The engines that this paticular tender went with: the G800, GN800 and F800 - in all cases the engine bodies were made of cast metal, not the very light weight composite alloy of which the tender body was made. Whether the coal load might ignite the problem seems improbable, given that a number of the 31X series cars made from the same kind of alloy had the same oxidation problem and they didn't carry coal.

Peter Neumann
Offline Dave  
#24 Posted : 18 December 2004 02:28:56(UTC)
Dave


Joined: 22/08/2004(UTC)
Posts: 86
Location: , Southeast
Well,

It looks like "Old Zinc Pest" is is headed for the big layout in the sky.
I got the tender apart - there was an unsuspected screw - see below.
UserPostedImage

Dave
Offline Dave  
#25 Posted : 18 December 2004 02:31:45(UTC)
Dave


Joined: 22/08/2004(UTC)
Posts: 86
Location: , Southeast
The sad part is that after using the nylon brush, it really did not look any better.
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Offline laalves  
#26 Posted : 18 December 2004 03:46:10(UTC)
laalves


Joined: 10/02/2004(UTC)
Posts: 2,162
Location: Portugal
Quote:
[size=1" face="Verdana" id="quote]quote:Originally posted by Dave
<br />The sad part is that after using the nylon brush, it really did not look any better.


Try the brass brush as I suggested earlier.

Luis
Offline Dave  
#27 Posted : 19 December 2004 02:41:02(UTC)
Dave


Joined: 22/08/2004(UTC)
Posts: 86
Location: , Southeast
A stiffer brass brush took more of the rot off the inside of the tender, but there are places on the inside and outside of the casting where a even a fine brush will not go.

If there is a chemical way to stop the rot, then I can seal it and paint it. If not I will probably let nature take its course. The loco itself must be of another alloy as it is not rotting.

I also have 3-4 early wagons that are showing small signs of rot coming through the paint, so a chemical that would stop this would be welcome

**** Some of you are probably in contact with Marklin direct. Would you please ask if they have answers ? *****

Thanks
Dave


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