Mazak New DP1?

[Bobby B]

Hi

does anyone know if the new DP1 in metal (Mazak?) will have the same issues of old, or have processes improved today?

[LTSR_NSE]

Firstly Mazak (an old UK trademark) & Zamak (collection of even older international trademarks) are not particularly useful/accurate descriptions considering none of us are privy to what licences/IP the Chinese factories producing/casting the metal are operating under.

A more accurate description would be a Zinc-alloy.

The contamination (which leads to expansion or contraction & ultimately disintegration) is due to Zinc of a too low purity being used in the alloy.

Considering the problems with Zinc contamination affected several model commissioners (formerly manufacturers) in the early 2000s when they started using Chinese production, it is extremely unlikely today that they wouldn’t include the necessary Zinc purity in the specification.

Whether that will completely prevent a recurrence of the issue, only time will tell - but it did succeed decades earlier (when the problem was encountered) in UK manufacturing.

The difference appears to be that UK had/has national standards that can be altered when issues are encountered, preventing any future recurrence. Whereas (it appears) Chinese manufacturing uses case-by-case specs & unless everything required is specifically detailed, there are no/less/worse default standards of quality.

[Bobby B]

Thanks for the reply LT&SR which is extremely informative. In your opinion is there any storage conditions and maintenance of this type of model using this material that might help reduce any potential long term effects?

[ellocoloco]

Bobby,

My understanding of mazak/zamak rot is that if the model has it, it is just a matter of time before it starts to show and the model fails. Storage conditions don't appear to make any difference but dry and ambient conditions may prolong life for any model.

On the plus side. I have 100+ locos and assorted diecast wagons and have never experienced the problem. I did once buy a crumbling DMU for rebuilding. It had failed after about 8 years (based on catalogue listing date and when I bought it on eBay) but I knew in advance and had plans to deal with the remains.

[threelink]

Mazak rot is caused by impurities in the alloy mix itself and by nothing else. Storage conditions are most unlikely to have any effect, but dry storage without extremes of temperature is always advisable. There is no maintenance arrangement that will prevent rot - if it is going to occur, it will and nothing will stop it

[Bobby B]

Thank you both for your added comments as all these posts give me a much better understanding of the process and it gives me confidence in modern newer metal models which I’m sure are of excellent quality using today’s standards of production.

[Bulleidboy]

Rather like ellocoloco I have 100+ loco's and have never experienced "the rot". My loco's are all stored in their boxes and indoors - so warm and dry. However as has been said "if you've got it you've it" - and some of my loco's bought in the early 2000's have never seen light of day - other than the day they were purchased/arrived.

[threelink]

I too have many locos, most of them ancient Triang or Hornby based with mazak chassis, stored in cardboard banana boxes in a bedroom. I have experienced only one instance of rot, in a mazak chassis weight of a relatively recent Lima Crab loco. The weight went for scrap (as did the loco, eventually, when I found out that it was much under scale). Mercifully, rot is not transmissible. It will either happen or it won't but if it does it will be confined to the individual loco in which it occurs.

On a separate issue has anyone come across plastic rot? I had some old 1950s plastic dolls house furniture set aside for a dolls house for a grandchild. The furniture was stored in a cardboard box in an insulated loft room for many years.. The plastic was a hard shiny sort, not at all flexible. Out of the blue one of the chairs started to disintegrate into a liquid goo with a vaguely vinegary smell. I outed it pronto and there has been no recurrence in the remaining furniture. I have never come across this before and have no idea whether polystyrene loco bodies can suffer such a rot.

[sxbiker]

@threelink, funnily enough, I had a problem quite recently with a flat screen TV when the plastic casing suddenly burst out in blisters. When pricked a liquid oozed out. The TV was still working but stopped shortly after the discovery. I was told that this was a problem with some "phenolic" plastics. I don't know if this is the same problem that you had.

[ColinB]

I thought it was a well known fact that plastic after a number of years goes extremely brittle. Car bumpers are an example but the other thing where it really shows is in those under bed boxes. I had a couple which after a few years disintegrated as I picked them up. This definitely depends where they ate stored.

[threelink]

@sxbiker. That's interesting. I'll research phenolic plastics (whatever they are).Thank you.

@CO. The brittleness problem is well known. In this case the plastic had not gone brittle but had simply decomposed onto a gooey mess and I don't think storage conditions were to blame (boxed in cardboard so in the dark in an insulated, well ventilated loft free from extremes of temperature). Only one item in the box was affected - all the others were fine. Bit of a mystery.

[threelink]

I have done a bit of on line checking and it seems that the plastic rot I mentioned is a variation of the cellulose acetate problem that many will be familiar with in relation to early Triang locos and rolling stock. Apart from the dolls house furniture my only experience of it has been distortion of loco body shells but apparently it can cause decomposition into goo with a smell of vinegar. It seems to affect old films and dolls and is known in the doll museum world as sad doll syndrome. It's irreversible, untreatable and infectious to other items of the same material. I routinely throw out any cellulose acetate loco bodies I may acquire but do have a few items of rolling stock which I believe to be cellulose acetate so I shall be keeping a careful eye on them. It makes you wonder what else might be out there intent on destroying our models.