Various Materials And Longevity.

[Mountain Goat]

We have all heard about chassis rot due to imperfections in thw mazak material, but what about other materials like plastic, resin etc? Some older plastic bodied models have showed signs of warping (E.g. the earliest Triang examples and other makes), but these issues were soon solved as manufacturers of plastic toys and models adapted the formula they used. However, sunlight is a well known destroyer of plastics and even the best plastic windows or facias, guttering etc can show signs of brittleness and damage usually after about 20 or more years as the products start to return to their origional form. (Steels rust, aluminiums corrode... Everything only lasts so long. Even weather exposed rubber tyres start to break down and rot as I once found out the hard way when I went to move a bicycle I had not used for two or three years and where the damp barn floor had been in contact with the tyre, the tyre had gone and the aluminium rim had dissapeared. Only a few rusted spokes remained.
So what about our models? How long should we expect them to last? What does last without any issues? Looking at older models, tinplate lasts if the rust does not set in. The Hornby Dublo cast metal bodies and chassis do tend to last. Though the very early Triang plastics were prone to warping (The ones where coaches were only half the proper length etc) but after this they were fine if kept out of strong sunlight.
Resin. Many kits are made from resin, but how long does it last. It does turn a more yellowy colour as it ages but the material seems to retain its qualities. No warping. No brittleness. (Resin can be broken with force but this is a natural quality. In other words it is not that much different from a stiff plastic (The plastics that snap rather then bend if too much force is applied to them)). The only issue with resins so far are that I don't believe the current mixes of resin have been around long enough for a lont term assesment, though some resins used in the manufacture of fibre glass bodied motor vehicles have certainly lasted. This is their achillies heel as one can have an immaculate looking fibre glass vehicle (E.g. A Reliant or Lotus or one of the many makes that used fibre glass) where the body looks fine, until an MOT is tried and the metal chassis has corroded. The immaculate looking fibre glass tends to hide the rotting chassis. Fibre glass resins (The part that gives a smooth outer surface for the vehicles body) have shown they have lasted the test of time. It is not the same mixture as most resins used for model railway purposes, but it may indicate that though ones lovely resin kit may start to turn yellow before one gets to make it, it is not so much of a concern.
Turning back to plastics, the materials do last a good while but in old age they either warp or become brittle. How long this takes depends on the individual plastic mix along with its colour, but one should get a good 50+ years from most of them when used on a typical model railway, which by then other more mechanical issues like weak magnets may be more of a concern.
Now how about Das modelling clay, plaster of paris etc? Clay pots do last a great many years. They do break down when one finds them underground in damp conditions as they tend to flake rather like an incorrect mix of concrete. Would we expect Das and plasters to do the same? Fine in an enviroment friendly to the material concerned but difficult when the material is exposed to an enviroment in which is hostile to the material concerned. For plaster of paris dampness is an issue. Das is basically a clay so dampness may be less of an issue. However, if the material is kept overly warm and dry does it break up like cement does when ones added too much cement and not enough sand?
There are a great many different materials used with our models and model railways, each one having their own properties. For most of us who may only use our railways for a few years before we make another it is less important. But for those who want their models and layouts to last, the materials may become a more important issue and hence why my thoughts are along these lines.

[IanS]

An interesting and thoughtful commentary. Another set of products that are coming onto the market to be considered is the 3D printed items.

The are usually of a plastic type, although the chemists will tell us that they are very different in a number of ways. They are so new that it will be a very long time (hopefully) before the degradation noted in older plastics will be obvious.

[Mountain Goat]

I didn't think of 3D printers. The potential is amazing where it is possible for a naval vessel to print out spare parts they may require during their journey, thus saving space which would otherwize be allocated to keep spares.. No doubt other materials will be invented to be used in 3D printers.
Some materials are available which would seem ideal in theory for model railway use. Take a portable layout as an example. The ideal qualities for the structure of the layouts are to be light and strong. Well, how about fibre glass or even carbon fibre in the forms of prebuilt structures to use? Fibre glass has been proven to have a long life. Carbon fibre is still a relatively young product but it has been with us a while, and maybe for bicycle use it may not be a very long lasting product (There have been quite a few failures of early CF bicycles though designs have been changed to compensate for these issues both in the material and the fittings), but for model railway use where we are not actually riding on the material, could this offer an ideal solution as carbon fibre is a relatively cheap material in its constitute form.

[footplate1947]

I would like to ask a question about this Mozak rot if any body knows. I have an old Die cast loco body which has been away in a box for years and I noticed the other day that the the rear panel of the coal bunker had developed small cracks around the rear of the bunker. I presume this is Mozak rot. I am not sure because I have never had this happen to any of my models before. I assume this has been lke it for a long time because I have not looked at this loco for ages, years even.
My question is, can I just fill the cracks and paint it over to repair it or is it a right off meaning the cracking will continue. .....John

[brian1951]

It will continue John, it swells first then slowly disintegrates im affraid.

[footplate1947]

I was afraid that would be the answer Brian. So the body is for the bin. Thanks Brian

[brian1951]

Just make sure its mazak rot before you discard it, i have not seen it in die cast bodies myself, only in chassis.

[Mountain Goat]

Could one add some sort of glue into the cracks to save the model? What model is it?
I have heard of mazak rot destroying whole bodies of trams. I have a book about trams which is based on collecting toy trams, and it shows a picture of a dicast tram body which is in a state. It was one of the few surviving trams from a certain manufacture from many years ago.

[Walkingthedog]

I have many diecast things and the only mazak rot I have seen is on one Hornby chassis.

[brian1951]

A little tech info on mazak, https://web.archive.org/web/20110716065 ... ang~en.pdf