Early Lima OO product mouldings becoming fragile?

[Mountain]

But my coaches have been in the loft nearly all their working life, no skylight so the must be another reason.

Jim

Could it be the type of lighting you use in the loft?

[Ken Shabby]

The loco which I most commonly see with a brittle body is the Hornby Dublo R1. I've come across quite a few with the rear buffer beam and bottom of the bunker broken, and it's nearly always the green version and not the black one.
Before I got back into Model Railways , I spent a decade collecting old Matchbox models. I once bought a really awful looking car, number 37 in the range the 'Soopa Coopa' from the boot fair. The model was good only for spares, and when I tried to dismantle it, the plastic interior moulding crumbled to dust. The model would of been about 30 years old at this point. Fortunately this was the only time I came across this problem, and at one time I had several hundred models from the 70's era. This made me think It could of been down to a batch of poorly mixed plastic.

Ken

[Ironduke]

Plastics like polyurethane decay in the presense of their own fumes. You'll often find that anything made of polyurethane, if left in a draw or box, will be sticky and horrible to touch. Perhaps there are other plastics that do the same?

[Bufferstop]

I think there's a clue in the Rovex banana coach roofs in the model shop window, if some of the plasticiser hangs around in the finished product and will have a small slow acting effect, wouldn't subjecting it to strong sunlight step up the rate at which it happens.

[Meister]

The loco which I most commonly see with a brittle body is the Hornby Dublo R1. I've come across quite a few with the rear buffer beam and bottom of the bunker broken, and it's nearly always the green version and not the black one.
Before I got back into Model Railways , I spent a decade collecting old Matchbox models. I once bought a really awful looking car, number 37 in the range the 'Soopa Coopa' from the boot fair. The model was good only for spares, and when I tried to dismantle it, the plastic interior moulding crumbled to dust. The model would of been about 30 years old at this point. Fortunately this was the only time I came across this problem, and at one time I had several hundred models from the 70's era. This made me think It could of been down to a batch of poorly mixed plastic.

Ken

Re. Matchbox cars, the interior moulding crumbling to dust happened to me a couple of times as a kid in the mid-1970s when they were new. One of the cars was the Iso Grifo and the other the MG 1100, both with Superfast wheels. They were bought from the local Post Office and from the boxes must have been in stock for a few years in a display cabinet which caught the sunlight. Never happened with any others so a batch of poor plastic could be a factor but I think prolonged exposure to sunlight/heat also is.

[Lysander]

Early Rovex products were extremely sensitive to daylight. Any modelshop which put a circle of Triang(Rovex) track in the window would in a very short time have an example of the banana shaped cab roof. I'm not talking of the kind of bowing which would only be noticeable against a straight edge, this would lift the two ends out of a coach body and allow the roof to fall off.

I’ve a feeling that those early Rovex coaches had acetate rather than polystyrene roofs. It was particularly unstable and few coaches have survived from that period with completely flat roofs.

Graham Farish OO Pullman coaches had exactly the same problem and I have yet to see one with a completely unspoiled roof - a shame, as they had very nice body mouldings. Their ‘normal’ OO coaches often turn up with cracked ends too and I have seen too many for it to be simply a consequence of rough handling. The cracks are hairline though and easily remedied by a capillary application of Mekpak or similar (which make it sound more like a stress crack than a degradation of the plastic).

By the way, does anyone remember from the ‘50s and ‘60s retailers lining their sunny windows with transparent orangey screens to filter out the UV and prevent fading of packaging and products? Can’t remember when I last saw that! It wouldn’t have dealt with overheating though.

Tony

[GeraldH]

I had a Lima 117 DMU which was boxed up and stored away from any light for 18 years. When I reopened the box, the bogies had turned grey'ish and had some fine grey dust on them. I brushed off the dust and everything seemed fine apart from the slight colour change. The bogies didn't seem any more brittle, but then I didn't try to remove the wheels. I no longer have it, but I expect that it is still happily running somewhere.

[Ken Shabby]

Sorry to dredge up a 3 year old post, but I bought this today for £4. It was boxed, but has the previously mentioned faded grey bogies.. One of the bogies was detached because the mounting had sheared off.
I have s couple of spare bogies, so it will be back in service in a couple of minutes.

As an experiment, I tried flexing and bending the bogies to test their strength . I found that with the exception of the already sheared off mounting, the bogies could still take a fair amount of punishment before they broke up.
The coupling hooks were salvaged for my Lima Class 33
Ken

[Bigmet]

The bottom line in all this, is that polymers are 'novel materials' and the earlier any particular formulation was produced the more likely that unexpected deteriorations may occur. The horrible gungy mess of deteriorated light seals on what were expensive large format and 35mm SLR film cameras perhaps makes the advent of solid state rather fortunate?

[Dad-1]

Age decay.
Something I'm learning about !!

Geoff T.

[Mountain]

Glad you have spare bogies. Plastic discolouring is less of a concern. Is the structural integrity that matters. Glad this aspect was ok. There are types of plastic which fall apart as they fade or disscolour. PVC is one. Lima bogies are more solid and have a degree of flex to them as I did check that on the odd few things I had which had disscoloured, otherwize I would have been concerned. The only real model railway item that feels brittle with age apart from very early Triang acetate bodied models is the Jouef bogie tanker body that I cut ready to make two separate tanks for 0-16.5 use. The modelling clay/superglue mix supports the structure well on my tanks. The tanker body seemed ok until I went to cut it, and found the plastic so thin that it surprized me, as I assumed a thicker plastic structure. Not sure if the age of the plastic made it brittle though. I think it was how thin the plastic was made and the type of hard plastic (Not flexible) they used.
I don't recall other Jouef Playcraft items being made so thin like that, but I could be wrong. No wonder the things are so lightweight! Hornby tankers were of thicker plastic as I recall, but I do question how long modern highly detailed models will last because their plastic is so thin in places to get the detail, that it has less overall structure to it, so if it is effected by age, it is more likely to start falling to pieces than the older thicker models made from more flexible plastic types. I believe that the thicker bendier plastics will last a lot longer than the thinner harder plastics.

Mazak rot scared me with models because it is a bit more of an unknown. (Unknown as in which batches happened to give issues... As it could be years down the line when one can discover the issues on ones locos!)

Another unknown are resins. While resins used in casting have been around a little longer and I have not heard of any issues other than they can be brittle anyway as they tend to mash a bit like a plate if they are dropped from a height (Easily repaired if it happens as long as one finds all the pieces and is a material that is very easy to work on), the resins used in 3D printing are more of an unknown. The bendier types seem to me like they will last ages and ages! But other types may not. We do not know as yet as time will tell.
3D printing is a realm I have not gone down, but is fascinating what can be done, as in theory the idea could use other materials as well. Though this is a theory I heard, but a certain Navy and Army was mentioning that the future is in 3D printing as instead of taking loads of spare parts with them incase they needed to replace anything, they could in theory ake a 3D printer with programs for every part, and just print replacements as needed. The theory is amazing!

Regarding broken or missing plastic parts in regards to our hobby... One can copy them in resin if one has a good one to copy and no new parts are available, but one needs a good one to copy. I was surprized how versitile a resin casting kit isif one also uses playough to cast into for "One off" single sided castings. (For multiple castings, or "Good" castings one can use the proper moulding rubber supplied in the set).