BOLT BARRIER, compound for Tesla coils

Excerpted from “The  Tesla  Phile” newsletter of May 1985 written by
       the late Peter Lefferts.  Provided by Gerald O’Docharty Feb. 1994
                      BOLT BARRIER, compound for Tesla coils


       To have an easily castable compound for insulation that is tough yet
       slightly resilient so that stress  cracks will not occur.  Available
       kitchen materials and  low  melting  point  are very  important.  My
       primary use will  be  to  cast  insulation  between  the primary and
       secondary using cardboard molds. The  object  is to wind the primary
       closer to the  secondary,  depending  on the insulation  to  prevent
       flashovers between the two windings.

       Paraffin, shredded soft  polyethylene  (old, translucent, coffee can
       lids etc.) (maybe   clean  clear  polyethylene   sheeting   commonly
       available. G.O’), salt, & two large pots… one of  which  will  sit
       easily inside the  other.   These  pots should be stainless steel or
       good uncracked glass-porcelain covered.

       First step is to make up a high temperature  double boiler where the
       inner pot sits in the water. Some sort of support is  needed  so the
       inner pot doesn’t  sit  on the bottom. Put enough paraffin blocks in
       the inner pot to supply the expected  need.  The inner pot will have
       to be weighted down because the outer pot should have  enough  water
       added to come about an inch above the melted wax level.

       Boil the water  while  adding  salt  to  it  until no more salt will
       dissolve. this raises the boiling  point  for  a better product, yet
       greatly decreases the chance of flames.

       When the water is at a medium boil with most salt dissolved  and the
       wax melted, start   adding  the  slivers  of  flexible  polyethylene
       (avoiding other plastics that are  stiffer or make a white line when

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       Stir every few  minutes  to  prevent  the  poly from sticking to the
       bottom and browning the wax. When about 1/2 the poly appears melted,
       add some more. Add water slowly to the outside pot to keep the level
       an inch higher than the plastic level of the inner pot.

       As soon as a hint of cloudiness  appears  in  the  mixture,  or  the
       consistency of thin oil appears, stop adding poly, and heat and stir
       a little longer.

       A mold of good dense cardboard, glued watertight  sides  and  bottom
       with ample epoxy  should  be  prepared well ahead of time, also seal
       any wire joints likewise. Do not use other plastics such as Acrylics
       as molds, practically all epoxies  and  hard magnet wire insulations
       will stand up  to  the  heat  and  solvent characteristics  of  this

       Pre-heat the mold  cavity  using  an oven for small objects, or hair
       drier for larger ones. If oven,  pre-heat  it  250  deg.F.  and wait
       until well stabilized before putting object in. If  hair drier, heat
       until a metal  part  will  sizzle  slightly  when  touched  by a wet

       Be sure that if a Tesla primary is  being  molded  that several taps
       for tuning are brought out through the mold. Also  if  you  want  to
       take the cardboard  off later, smear the inside with silicone grease
       (easier to paint the cardboard though).

       Pour rapidly without splashing; this  stuff  burns  skin  worse than
       boiling water. Shake gently to bring up bubbles.  If  a  small  leak
       appears, patch with  magic  tape  and  blow  with hair drier on cold
       setting until the plastic in the leak has well solidified.

       Bolt barrier is at least an 8 times  better  insulator  than air. It
       can be carved quite easily and very smoothly, and in  fact  may make
       an excellent amateur’s sculpture media.

       If done slowly,  the material can be drilled and sawed with ease. It
       makes good light duty custom bearings  for  models  etc.  Almost any
       household solvent may  be  used  for  short  term  cleaning  without
       effect…turpentine has some polishing action.

         If you  have comments or other information relating to such topics
         as  this paper covers,  please   upload to KeelyNet or send to the
           Vangard  Sciences  address  as  listed  on the  first  page.
              Thank you for your consideration, interest and support.

           Jerry W. Decker………Ron Barker………..Chuck Henderson
                             Vangard Sciences/KeelyNet