Re: Pot metal - was something else

On 2026-08-09 14:20, The Natural Philosopher wrote:
> On 09/08/2026 01:47, c186282 wrote:
>>   The alloy does not seem very resistant to vibration.
>>    It's soft enough you'd THINK it would be, but its not.
>>
> The problem is mainly that its has no fixed composition, Its random non 
> ferrous scarp mainly. Use a magnet to get the iron and steel and melt 
> what is left over perhaps
> 
> 
>>    Most aluminum alloys and 300 series stainless are
>>    not super-good with vibrations either - though
>>    better than 'pot metal'. I've seen 'magnesium' tire
>>    rims crack too.
>>
> Pot metal is heavy and brittle in my experience.
> 
> Came across it back in the day in toys, carburettor castings, thermostat 
> housings..valve covers..all stuff that needed shape retention but no 
> great strength
> 
>>    Only steel - esp nearly pure iron - seems to stand
>>    up to vibration, but it's HEAVY. Some cast iron,
>>    like that previously used for engine blocks, can
>>    be pretty good but will fracture on a sharp impact.
>>    I've seen old cracked engine blocks too.
>>
> Cast iron is brittle.That's why they used to use wrought iron - but it 
> was expensive.
> Then making steel got super cheap and that was that. Whole generation 
> learned to treat and alloy steel to get almost whatever you want
> 
>>    Plastics - they start 'crystalizing'/decomposing
>>    the instant they're made.
> 
> Not all of them. Like steel, there is a huge range. There's many a radio 
> case made of 'Bakelite' or stuff skinned with 'Formica'  or floored with 
> 'linoleum'....still functioning
> 
> Epoxy and glass fibre PCBs dating from the 1970s are still OK, as are 
> phenolic resin items
> 
> PVC however is very short lived, In the sun

PVC is used here for window frames and blinds. I had a place with such, 
40 year old, and good. Yellowish, though. And more brittle.

> 
> Nylon is intermediate - UV ageing often gets it
> 
> Jury is still out on polycarbonate, ABS  and ASA.
> 
> In fact one of the eco gripes about plastics is that they *don't* degrade.

They fragment into microplastics.

> 
> Nevertheless there are plastic gobbling bugs thriving at the bottom of 
> the sea apparently, eating all those microplastics.
> 
> Beware the SweepingStatement...
> 
> 
> 


-- 
Cheers, Carlos.
ES🇪🇸, EU🇪🇺;