I just  got   the Poly Fastener sample  from  Northern Green  House   THANKS  BILL!  
 And  some  samples of  the  11 mil   " poly  woven"  he   mentions in  his  web site ,  I'm guessing  some of  you  have  ordered too . ?
 First impression .  My  8 inch piece is   white  and lite !   With  the  single 11 mil  sample   in it ,  I  CAN NOT pull it  out.     When I  take  BOTH  samples of  11 mil  and put  them  in  BOTH  ways  I CAN NOT  pull  them  out  !!!  My Fingers  Hurt  trying!  And I about popped  blood  veins  in my  head ,,,, Thats  How hard I  pulled ..MANY TIMES ...and constant   ... and I  ain't  no  weakling .  
  HOLY  CRAP GUYS  !   If  you  were to  glue  between  your  envelope  pieces WHAT  EVER THEY  MAY  BE   with  ANY THING   that  even  sticks  even  just  a  little ..... Envelope  seaming  air tight   is  DONE !  
 If you  wanted  to  be  100%  sure  the   thing  cant  un zip ,  A small pop rivit  through the  assenbly  every 16 inches or so  would be   plenty!   Drill  the  hole  squrt  some  5200 in it  and rivit it .  Done !   I'm  Amazed !
  On  to  the  11 mil Woven Poly  .  DAMN !  this  stuff is  tuff too !  . But   it only comes   25 foot wide .  Bill does  heat  seal   So   it  could  be ordered  to   sizes   useful .   The  heat  seam  Bill  sent   ..I cant pull it  apart  ether .  It is  a lap  seam   . 
  All Quality  stuff here  guys !   I'd  fly  with it... No Problem-o-   !  In Short  ,    I   IT!  
 Answers and Solves   a LOT of  Questions  for  me .  Done  Deal  here .  
 

Sounds great.  Can you tell me the weight on the 11 mill sample per square foot?

I didn't get  a  1 foot sample  .   But  a  search  shows up  a 12 mil (woven)   at  60 pounds   for  1000 sq  ft  ( MSF)
 So it  would be less  than  that .

   I really like the idea of the poly fastener. It eliminates the need for a heat welder, and the risk of a home grown seam letting go. Apparently it should work with any plastic, so that's good too.
   It would be nice to see if they offer corner pieces for a ship like Nav is building. With the webbing available from the boat wrap people, and some aluminum plates for web mounts, anybody should be able to make their envelope.
   We have good plans for the gondola, too. I picture a swiveling gondola under that nice Russian lenticular eliminating  a lot of weight and complications.

  Yes  Any plastic  could  work  as long as you backed it up to get  the  right  mil  thickness so  the Poly fastener  snaps  tightly . Also   there are  poly fasteners   designed for  different  mil  gages .  For our application, the Poly Fastener system  will   require  a  quality  glue  seal  between  the envelope films  to  create a  air tight  gasket IN  the poly  fastener .   The Poly fastener   will more  than make up for  the  lack of  holding force  that  just  a  glue will have on  plastic ,   But  the  glue  Will need to  be there  to make it  gas tight Performing   more  as a gas proof gasket  now  , with  the  clamping force of the Poly fastener  insuring  it  stays together .  
  For corners ,  if   the poly fastener is on  edge   the   insert seal  strip  can   do  a  90   ( may  need to  heat form it  )  and  add a backing  L  bracket  held on  with  5200  on back of  the  channel  side .  
  Trying to do  a  90  laying  flat   may need  a pre formed  90 L strip  out of  something  reasonable  that  would  snap in   like  the insert strip does .   I  would   pop rivet  this  one in just  to be  sure . Adding a dab of  5200  in the  drill hole   before installing  the rivets  so  there  wont  be any  gas leak  there.   
 The  channel  part would  just butt joint  or  45  angle  cut  with  a  formed  angle  5200 -ed  in place   depending on  which  way you  turned it .  
 I'm  going to order  some   for  a  12 foot  dia  lenticular  And I  also  would like to  try it  with  the  2 sheet construction  method on a  standard  cigar  shape .  Both  cold air inflated to  failure.  Thats  gonna be  FUN! 

I see construction going like this:

• We lay down two layers of plastic film.
• We mark out the circle we want.
• We spray glue the perimeter together outside of this circle.
• We cut off the excess outside of the glue.
• We inflate the balloon and heat shrink the perimeter wrinkles out.
• We poly-fasten the perimeter over the glued film. 
• We rig lines from load tabs hanging from the poly-fastener, to the gondola.
• We trim any excess material hanging past the fastener ring.

I agree  with  everything  except  #3   I  think  you  are going to  need a  "  thick " quality  adhesive  such  as  5200 urethane marine adhesive  .  So  the Poly fasteners  compression  force  has  a  "cushion" of  glue  to   seal into, providing  a  gasket effect .  I don't think  spray on   alone   will  produce  the mil-age for the   gas tightness  we're looking for . 
 

OK. I was just thinking the glue would make the rest of the construction process easier. I didn't think of it as a way to improve the poly-fastener seal. 

I am working on building a model with the above steps right now. Hopefully it will be done in time for the conference tonight. I don't have any poly-fastener so I will stop at that step. 

 Yes  I  think   from looking  at  the Poly fastener   this will be  a  gotta do  thing.  Although  it  Holds  tight  enough    that  the plastic  will  rip  before it lets go  from  friction .  Its  still  not enough  to  be  considered gas tight .  You  will  need  a  Mil or 3 of a  flexible  sealant  between  the  envelope half's ,Inside  the poly fastener  to  make it  air tight when it  clamps down  tight with  the  insert strip .   .  
  Also   Looking  at  this  it looks like  you  will need to     drill through   the insert strip  and u channel part  for   bolting hard ware  on it  Or  bolting  the Hoop  ring to it  .  And  use  the  same  sealant / adhesive  in  the  hole  because   you  will be drilling through the  envelope  too . 
 There  might be  different  types of  Poly fastener  besides  the  white  sample  I  was  sent . I know  they  sell   them  for  different Mills of  fabric.  like  for 20  to  30  mil stuff.  Like  the Black  one  used on  the hover craft   link.   It  indeed looks  bigger  and  thicker  .  It  "may"  be more structurally  sound   for our   applications than  the  white  sample I have  .   As  we  can  always  add backers  to  get  the mil-age up   so the  fastener  Clamps  tight to  our  thinner   films. But  giving  us  the   structure  we  need   to  securely  attach  hardware too .     The  white sample I have  Looks  kinda  weak to me  for  this .   If I used it  (  white sample) I  would  use  a  bracket   strip  that  fit  inside  the U channel  and over the insert piece  clamping the  whole Poly  fastener  tight  between  front strip  bracket   the  back  attachment  bracket .  I  would  5200  these  brackets in place too .    

[[   You  will  need  a  Mil or 3 of a  flexible  sealant  between  the  envelope half's ,Inside  the poly fastener  to  make it  air tight when it  clamps down  tight with  the  insert strip]]]

   Something really good and cheap for this is "Polyseamseal" an adhesive sealant from Ace Hdwre for 4 bucks a tube that fits in a caulking gun that costs 7 bucks. You cut the applicator tip to a small size and you get a small bead that sticks but is easy to pull off when dismantling for transport by trailer.

it is called latex adhesive caulk

Some of you know what a wire "Nut" is, it screws down on a group of wire ends to tie them together.  Try a wire nut to seal the end of your caulking gun in between use, it screws down and stays, and screws off.  It beats trying to dig out two inches of solidified caulk the next day.

I was wrong   on  the  width   the  poly  woven  comes in   , 12 foot is  the  widest,  not 25 ft . 
 Also  got  feed back  coming on  heptax  film , the  high  gas  perm  resistant stuff. 
 Good  fix  for  the  clog problem   I 47 ,  I  useualy  use a 16 penny  nail  or a deck  screw .  

Good news, how much does the heptax film cost?   Who is the supplier?

Dont know yet ,  Waiting for  the  US contact to  Get in touch  .  They  are familure  with heliun  Containments  .   So  Standing  by .

The heptax has been mentioned in previous posts: expensive and hard to work with ( and not easy to get). The permeation properties are excellent.

From our friends at amazon:

[[  Try a wire nut to seal the end of your caulking gun in between use, it screws down and stays, and screws off.  It beats trying to dig out two inches of solidified caulk the next day.  ]]

   Now I gotta kill I47.  8=0

    I've used tons of wire nuts to rewire my house and tons of caulk to seal the siding boards and never put the two together. It just goes to prove that...

I acquired a 100 ft roll of  White  Poly fastener  for  the  11 mil  plastic today . 
 This looks like  my  last  weekend and  free time for a  while because the  weather here in  SW Missouri   has   knocked us  down  and out at work  ( its  snowing  as I type this... another 5  + )  And  we're  way  behind .  Looks like its  going to  be  12 + hr / 7 days a week  every day  workable  until......  mid MARCH!..    ....SO...... I want to have some fun  tomorrow.
 I'm  going to  do  a large saucer CPS test tomorrow  with   2 sheets of  plastic  , no  glue, may try  tape if not too cold to stick   ,  and  just  see   what  will happen , or if  I can  get it  to  inflate  at  all  with  the shop vac / blower.   The  fresh  snow  will  keep  the  plastic  safe from getting holes  assembling out in the yard.  If  time permits , I  will  try   a  traditional  shape  using  the 2 sheet method as well .   Will try  to  get  some vid  up  of it all .  

Sounds great. I hope you have good results. 

Well  the best laid plans of mice  and men   laid to  waste  by  One  Stupid phone call ,  yeah , I got called in to  WORK  this  weekend  12  hr  shifts ,  And  I JUST got Home  about  30 min ago .   yeah ,  its  Nuts   .
  Anyway   I  grabbed  what I got  done after  the phone  call,  crammed it in  the truck ,  and  was  able  to   play   in  that   theater I  filmed  the  PHA   in  this  evening  .   I have not  inflated yet,  maybe tomorrow . I still have to tape up  the  inflation duct .
  My  disk is  9  foot  in  dia , 2  sheets  with  a fill  duct    ,Looks  just like  a round foil balloon  does .
 I  taped   the  2  sheets  together  with  small  strips of  gorilla tape   just to hold  them  together, ( More on  gorilla tape later)  I  started  the insert strip  ends of the  poly fastener on  the  opposite side of the  fill duct  so  the  C channel parts  would meet at  the duct 
  Now  when  you  get  this  stuff , it's in  a coil   , Your going  to  think   its an  unworkable  mess ,  but  as it turns out   it  flows  nicely  around  the  plastic envelope , and  made  a very  nice  circle !   One other  thing   you  need to do is draw a circle  where you  want  the poly Fastener  to  clamp  to,  so  its  all equal  following  the line  ,  I  failed to do  this step and had  a little more  in  some  areas  by just  free handing it  ,   I was  close  however.  
  Being  happy with  this progress  I stashed  the  work   until I can  get  back  to  it  .  It  did coil up  like  a   windshield sunshade does  but  with out  the "springy  snap" they  exhibit   ,that  was  Cool!    
 Now  on  to  Gorilla  tape  made by the  gorilla  glue people  .  A test piece  stuck  to  the  4 mill PE  and  would not  come off  without   ripping  the plastic  first .  I cant  get  the  PE  off of  the tape .  I did not  try  to  pre clean the  plastic ether ,  Just  right out of the bag   ,  taped it ,  and  ripped  the plastic  trying to get it off .   Wow!  this is  the best  Duct Tape  you  will  ever find anywhere . I can  see  many  Airship  Applications  using it  .    More   to follow . IM       

  It sounds like you are making good progress, congrats.
  Gorilla Tape is fairly new on the market, and they may be interested in sponsoring something that will get them good advertising. If someone can convince them that a ship will operate properly, and not turn into another 'Balloon Boy' incident, they just might help with the costs.
  We have talked about advertising before, but I see lots of ads on the sides of foreign ships. Without sponsors, a lot of enterprises, car racing, dog shows, etc., just could not afford to operate.