It's well known that prewar Gilbert 3/16" O cast pieces suffer from zincpest. But, a 1947 312 that is on my bench has me wondering if it is also affected.
I noticed that the left side of the tender is bowed inward, and there are numerous bubbles under the paint. If it was a sheet metal tender, I'd write the bubbles off as cancer lifting the paint from the steel. Being that it is cast, I am curious if it is zincpest. There is no noticeable cracking.
Has anyone seen any postwar AF like this?
Hi Jim - I've had a tender from the 1939-1941 with a bowed side also, but none from the postwar era. I wonder if the shell was swapped out from a prewar. Come to think of it I'm not sure if it would fit?
Ray
Bayville, NJ
Life is what happens to youWhile you're busy making other plans - John Lennon
I have five smoke in tender locomotives and two of the smoke units in the tenders show cracks and deterioration that appear to be zinc pest. I have also seen exfoliation (a layer of metal coming off) on tender shells. So zinc pest may be possible.
Ray,
Unfortunately, this shell is '47 production with the PRR herald and AFL lettering, which the '46 and earlier shells lacked.
Major,
Are those affected units limited to just '46 or '47 production? I installed a cylinder conversion kit from RFG in the tender in question, and didn't notice any signs of deterioration inside the tender. I am keeping my fingers crossed that it stays that way.
I have only smoke in tender locomotives from 47 production. I have converted one of the better smoke units to the piston drive. The deteriorated units were leaking smoke fluid like a sieve due to the microscopic cracks in them. The fluid was leaking through the sides of the units. I cleaned the smoke fluid from them and use thin super glue to seal the units and they have worked fine ever since. I have also used CA for holding together zinc castings of some prewar accessories with success. On a 322 Hudson (also 47 production) that was a repaint candidate, when cleaning the tender for repainting very thin flakes of metal were coming off the tender sides.
I know the difference between neglect or caustic liquids being spilled and left on a casting and zinc pest. I believe that this is zinc pest
I have a large collection of AF, just what exactly is "Zinc pest"? a rotting condition of Die Cast?
could I see a picture of it?
Ryan
Die casting is a technique for making castings of various metals, not a type of metal. Most die cast toy train parts are made of zinc, which is why zinc pest is a concern for us. It is caused by lead contamination in the zinc; and very small amounts of lead will do it. The result is weakening, swelling, and crumbling of the zinc.
Bob Nelson
sorry for the confusion..I know what die casting is... I own a salvage yard, and when we buy and sell "zinc" in the scrap industry for some reason its referred to as "Die Cast" was the lead used as a mold release?
Most of our diecast trains are made from a zinc alloy called ZAMAC. It is an alloy that is largely zinc, but it does have small amounts of other metals that change its characteristics dramatically. There are several types of ZAMAC that are commonly used. Here is a link for more information:
http://www.eazall.com/diecastalloys.aspx
Zincpest has been discussed at length in other threads and as always is an interesting topic. My reading and research has shown a lot of what has been said already. It seems that metallurgy was not as refined when these items were being made and that lead impurities in the alloy were quite common. Lead impurities would start a crystallization within the metal alloy itself that once started the crystals could grow. This crystal growth from within would cause swelling, bending, bowing, blistering and all sorts of related maladies to the Zinc alloy part that was cast. It is thought that high humidity or even more important a sudden temperature change(s) could hasten the crystallization of the alloy. Many think that if the piece has made it to this point with no Zincpest that chances are better than not that it will survive. Even still a controlled environment for your toy trains is the best prevention. No hot or cold attics or damp basements.
Also it seems that postwar American Flyer did have some problems with the 336 Northern tender chassis. I'm told one of the reasons there have been reproductions made is that this particular part was also prone to zincpest postwar!
Lover of all things Gilbert, truly a man ahead of his time.
To stop the warping problem with the early plastics A.C. Gilbert went to zinc die cast frames. Have you ever noticed how many New Haven passenger cars and baggage cars along with box cars with the die cast frames are cracked at the corners. This is due to the expansion of the frame due to zinc pest! Filing down the frame at the corners will relieve pressure on the plastic if you don't mind doing that to your train cars.
Gray CatNo hot or cold attics or damp basements.
Well that probably describes about 90% of us and our dad's!
Major To stop the warping problem with the early plastics A.C. Gilbert went to zinc die cast frames. Have you ever noticed how many New Haven passenger cars and baggage cars along with box cars with the die cast frames are cracked at the corners. This is due to the expansion of the frame due to zinc pest! Filing down the frame at the corners will relieve pressure on the plastic if you don't mind doing that to your train cars.
Major, I'm just curious did you ever confirm this with measurements? To see if in fact the post war diecast frames did expand? I know that a good many of my post war plastic shell New Haven cars have a slight bow in the roof that I always thought put extra pressure on those corner points causing the results you describe. Only asking out of scientific curiousity.. I do know that a prewar Royal Blue motor chassis I have did expand in just the way you describe causing the rods to knock (so to speak). This was confirmed with measurement. I'd love to hear the results of a comparison measurement. It would be nice to know how many of the postwar items are still affected by Zincpest. IT does seem for the most part that they got the formula down right after the war.
Thanks all for the replies so far. I'll get some pictures added as soon as possible.
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