Re: [TCML] Form materials, losses, carbon tracking, sealing

["Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>]

Hi Scott,

My large 13" diameter coil was sonotube. The form was prepared with 
thinned varnish to soak into the form. After applying the turns, the 
thicker coating was used on the outside. After I retired the coil, I cut 
it down into 3 sections. One section I gave to Terry Fritz for testing. 
The other two sections I still have. At one point, I did some 1:1 hd 
testing and removed the inside cardboard of the sonotube. I peeled it 
out layer by layer until I could see the winding. Since the inside was 
thin coated, this job was very easy. The coil was rather fragile. It 
held together very well but it was elastic in that I could press it 
inward slightly and it would  spring back to position.

This would be more difficult on a long form, but it's certainly 
possible. It probably helps to use an outer coating that is thick and 
flexible like Marine Spar varnish (since the coil will flex, you don't 
want the outer coating developing cracks). This is the coating I use on 
forms and mainly due to it's flexibility and it's an off the shelf 
product at hardware stores.

Take care,
Bart

Scott Bogard wrote:
> Has anybody ever tried building a coil on a cardboard form, applying 
> many, many coats of thick urethane or epoxy or whatever, and then 
> removing the cardboard form alltogether?  From what I understand of the 
> sonotube cardboard forms, they are meant to peel off once the concrete 
> is dry, so would it be possible to have a very delicate formless coil if 
> great care was exercised during it's construction.  Please note, I do 
> not consider myself careful enough to try this, I am simply curious to 
> see if anybody else did.
>
> Scott Bogard.
>   
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