Wanted: Small Quantitites of Tedlar

What gauge?

A little thicker than thinner is better. I want to make an air supported structure, roughly 20' or 6m in diameter. I am planning on cutting gores and need to seal them together somehow. ...

Even white or translucent (vs clear) is great for my needs.

Since this is non-commercial and coming out of my pocket, I am price sensative. But after researching, I think tedlar is a better covering for this use than most (tear resistant). ... But I do need to keep branches from falling and puncturing it!

Thank you for your response...

Hi s74,

"I am planning on cutting gores"

I don't know what you mean by this. What are gores?

I have been working with films for many years. I have worked with Tedlar before and it is very expensive. I think that you could get the properties that you need from a cast polypropylene which is cheaper.

You must be more specific on the thickness that you need. (1-mil?, 10-mil?, 1/8 in?).

Mike

Think pie-shaped wedges, only that 'bulge' a little bit. If you take a look at a beach ball from one end, the 'stripes' look pie shaped. Now draw a line around the ball along it's 'equator' (equal distance from each 'end'). The shape made by one of the wedges from one end to the equator is a gore.

If you cut gores like this, and join them on edge, you can make a round ball from flat material. The more gores you have, the better it approximates a ball, but the number of seams to deal with really goes up.

Does that make sense?

... Jack

Try here.

http://www.professionalplastics.com/TEDLARFILM

I saw a discouraging comment on their web page. Dupont is currently limiting sales to only aircraft and solar cell usage.

It is their product, but it seems odd to me their limitation on sales like that ...

they have limited production at this time and are supplying 100% of it to existing customer base.

I find that odd since it is over a 30 year old product. ... But possible.

I have only seen it used for wear resistance on wall covering at a 2mil, adhesive backed, laminate.

I'm guessing this would be too thin?

Part of my conundrum is that it might be OK at that thickness, but I am guessing thicker might be better. But if it is adhesive backed it might be laminated onto PVC or some other film, but it still would not have the toughness of the Tedlar.

I don't know where to get it.. but we used to use 6 mil as part of a solar glazing (at a small solar factory I worked at)... for which it was very well suited.. damn near bulletproof, and UV resistant...

we used to have contests in the shop to see who could punch through the glazings that were deformed. (waste) after the Tedlar had been heat-shrunk to drum tightness... you had to hit it with everything you had...at the right angle so your knuckle could cause the rupture.. it was not puncture proof.. an arrow would penetrate easily, but a cinder block would bounce off. amazing stuff..

the back side of our glazings was covered with very thin teflon..on 1" aluminum frames.. made a very high efficiency glazing with the trapped air.. We used 3M double sided adhesive tape on 2 sides each. (flat and side). then the whole assembly was heat shrunk in an oven, and sandwiched into the collector frame.

Chris

Yep, Tedlar is tough stuff. I was figuring if I could keep from cutting it, it should take almost any kind of abuse.

Out of curiosity about what temp to you heat it to to get it to 'heat shrink'? I didn't know it had that property. Or is that the tape that shrunk?

The temperature was not very hot.. we also used one of those paint stripping heat guns, held about 8" away to spot cure and remove waves and wrinkles.. so you can determine it yourself.. but this was 1980.. I don't remember.. the oven was homemade with metal strapping for heating elements.. and while there was a temp guage, I can't remember... it was 220 vac.. I remember that.

we would put each frame in the oven for about 30 seconds, once the oven was up to temp.. and could do a whole batch (30 frames) in a short period.. with 2 guys handling the frames. had to be careful not to puncture, as the oven ceiling supports was angle iron, and had sharp edges.

the heating element was a flat spiral, and wrapped around thermal thingies in the ceiling (no element below) of the oven... and so we made one bake for the tedlar, and flipped it over, and did one for the teflon. (same time duration) (I could make you a picture if that would help

after cooling we would clean up the corner wrinkles with the heat gun.

and definitely the tedlar itself was heat shrunk. sometimes there were difficult wrinkles that were just too large, and it took a long time patiently to shrink it.. but there was a limit, and if the shrink was insufficient.. because someone didn't lay the tedlar right, or the frame was out-of-square, then you simply coudln't remove the wrinkles.. for that reason, we evolved a bit of QC.. because after a while, you could look at a frame pre-shrunk, and know that you were not going to get that wrinkle out.. and getting the tedlar off after the tape has been set by the heat... difficult..

we also used a special pinch roller, which took rolled on the top and bottom edges and further set the bond.. if you did this while the tedlar/tape was hot.. it was a powerful bond.. near impossible to get off.

anyway... what is your application?

Chris

I have wanted to make an air supported structure that I could use as a temporary workshop for a few days at a time and be easy to take up and down (thus the air :).

For my 'needs' even polyethylene would do, but Tedlar would last a LOT longer (with puncture resistance and UV aging resistance. Also Tedlar, being a 'cousin' of Teflon, is also pretty resistant to 'dirt' attaching to it, and would be easier to clean with a 'light' power washer or garden hose.

If it worked out for me, I could see this as a 'product', but initially it is just a personal project. For my use about a 20' dia 'bubble' would be about right, and I prefer white to clear. If I decide to give up on getting the Tedlar I might just get some tarps or even some sheet polyethylene to do a prototype to see what other issues I face.

a 90x90 sheet of anything would 'cover' a 20' dia dome/bubble with enough left to have some 'play' in it and cutting waste. Actually a 70x70' sheet should be enough if there are few mistakes.

I did an air dome when I was a teenager in our front yard in the 'burbs. Kids flocked from a couple of streets around to play in it. I just rolled out a big sheet of black polyethylene my dad had, laid 2x4's around the periphery and duct taped the exhaust end of a whole house 'swamp cooler' squirl cage blower to one area and turned on the blower. The 50x100 plastic was about 20'wide and 70' long, more or less. But kids had fun for the day playing in and around it. I wish I had a few pictures, but so it goes.

I built a small storage shed a couple of years ago, in another province.. but it was just a 2x4 frame 8 x 8 x 8... sloped roof.. and I just stapled 2 layers of 6 mil poly over it.. it lasted a couple of years.. and I love the smell.. and I can totally relate.. althought i've never tried to build a pressurized air-supported structure.. it sounds like fun.

Chris.

We live on a 'Girl Scout' camp. So something like a dome would also be a real conversation piece. I could see it being used for the girls as well as a fun project for me.

Since I don't have any 'funding' for it, doing it inexpensively is one of my major issues.