Re: [ATM] dew heater ..Resistive Paint

[George Anderson <georgea@cam.org>]

Hi Malcolm

In a pinch try an auto parts store. They usually carry a resistive paint
for repairing rear window de-foggers. It is a little pricy but you
should't need much for a diagonal.

George Andesron
Montreal Canada

Clear skies and good health

Malcolm Macdonald wrote:
> 
> ----- Original Message -----
> From: "Jerry Reddell" <jerry.p.reddell63@sbcglobal.net>
> To: <atm@atmlist.net>
> Sent: Saturday, January 01, 2005 12:05 PM
> Subject: RE: [ATM] dew heater ..Resistive Paint
> 
> >
> > It is not cheap and I don't know if one can purchase it in a 1 oz size.
> > The
> > actual total resistance depends of the thickness, width and length of the
> > painted stripe... A thin, narrow, long stripe makes a higher resistance.
> > Thick, wide and short stripe give a lower resistance.  Application usually
> > involves use of a template to control the thickness ( squege type
> > application) or a template and empirically derived spray painting times
> > and
> > motions...
> >
> > For a diagonal, I would expect one could just brush it on relatively thin,
> > and let the external controlled current flow establish the wattage.
> >
> > Jerry Reddell
> >
> > -----Original Message-----
> > From: Bob May
> >
> > In the electronics industry, there is a product that is called "resistance
> > paint".  It isn't cheap as paint goes but it does an excellent job of
> > providing a resistance to current flow just like a resistor does.  The
> > interesting thing is that it is measured in ohms per cube.  Longer lines
> > of
> > the paint make larger resistances while wider lines drop the resistance.
> > If
> > you need more power then you scale the size of the patch up.
> 
> Jerry and Bob,
> 
>      Thanks for your replies. I wonder if it is available here in New
> Zealand. I will go shopping, armed with a printout of your replies, to prove
> to the glassy eyed sales people that such a product exists.
> 
>     Malcolm.
> 
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