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Re: Cap materials



Subject:  Re: Cap materials
   Date:  Thu, 17 Apr 1997 22:06:51 -0700
   From:  Bert Hickman <bert.hickman-at-aquila-dot-com>
Organization: Stoneridge Engineering
         To:  Tesla List <tesla-at-pupman-dot-com>

>   From:    Lord Talimar" <lordtali-at-mill.tds-dot-net>
>     To:    "Tesla List" <tesla-at-pupman-dot-com>
> 
> instead of mineral oil, try vegetable oil.  fairly close in dielectric
> value, and cheaper and easier to get a hold of.
> 
> Hope this helps.
> 
> LT
> 

> >
> > I'm about to start building some rolled poly caps, and have a question
> > about sourcing materials.  .09" thick polyethelene is not commonly
> > available, but .006" thick is.  Is it reasonable to use 16 layers of
> > this
> > thin stuff, or would this many layers be totally unwieldy?
> >
> > I don't have access to a vacuum pump to pump the cap down to remove air
> > bubbles.  Would the multi thin layers pose a greater problem in
> > harboring
> > air bubbles?
> >
> > Also, for the mineral oil, what kind of place does one go to for this?
> > Auto supply store?
> >
> > Gary Lau
> > Waltham, MA
> >

Gary and Lord,

Well... not quite. Mineral oil doesn't go rancid with time - while some
vegetable oils may unless they contain anti-oxidants. Also, all
vegetable oils tend to have higher dielectric constants than mineral oil
(2 - 2.2). For example, cottonseed oil is about 2.7, olive oil comes in
at about 3, and castor oil ranges from 4 to 5. Unless you buy pre-dried
oil prepared for electrical use, you may also have an undesirable amount
of water in the vegetable oil you use.

Safe cappin' to you!

-- Bert --