[modeleng] Re: Mica?
- From: "alanjstepney" <alan@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
- To: <modeleng@xxxxxxxxxxxxx>
- Date: Sun, 8 Aug 2004 12:48:45 +0100
I would guess that it is mica.
I have seen it flake and disintegrate due to age and heat, but not change as
you mention.
Might only do that under certain heat + pressure conditions.
On the other hand, I suppose there might be some substitute for mica
available today.
If there is, I have not come across it.
But, if so, I wonder how it would be for a gauge glass protector?
alan@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
www.alanstepney.info
Model Engineering, Steam Engine, and Railway technical pages.
----- Original Message -----
From: "Roger Mason" <roger.g3tdm@xxxxxxxxxx>
To: "Model Engineering List - Latest" <modeleng@xxxxxxxxxxxxx>
Sent: Sunday, August 08, 2004 8:41 AM
Subject: [modeleng] Mica?
Hi All,
I've just had a disaster!
I have a large electric soldering iron (300 watts). I was using
this the other day when a sort of Frying noise came from it. Shortly
afterwards I realised that it was cooling down, despite still being
plugged in and turned on. I quickly discovered that the element was
open circuit.
So in the "nothing ventured - nothing gained" spirit I opened up the
iron. I eventually found the secret to getting inside it and found the
element very easy to get to.
The element was a simple coil of heater wire insulated in sheets of
translucent material which I assumed was mica. However as I delved
deeper into the element the sheets of mica became "welded" together.
It appears that the element produced a 'hot-spot'. In this region the
mica has changed in appearance and texture. Instead of being sheet
material with a slippery feel, it was a pink brittle uniform
substance, which looked for all the world like the pink plaster one
uses on walls of a room. I carefully chipped this away and came to a
hollow lump of what looked like a black glassy substance - very like
silver solder flux which has melted and solidified. I presumed this
is where the frying came from - a little arc between the element and an
end wire.
My questions are - was this insulation material really mica? Does
mica behave in this way? If it was not mica what was it? Have the
chemists come up with a modern alternative for natural mica?
In the meantime I am trying to find a source for a new element.
The iron was made by Goot, a Japanese company who have a web site, so
I have asked if they have a U.K. dealer who can supply me - but maybe
someone on this list has this knowledge.
I look forward to the list's input on this topic.
Cheers,
Roger Mason, in St. Agnes.
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