Tuesday, November 19, 2013

Yurt Design - Canvas Shrinkage

Canvas shrinks.  I knew that. So when I designed the roof pattern for the yurt, I should have allowed for shrinkage but didn't.  Oh well, nothing that can't be fixed with a little more sewing.
Not only didn't I allow for shrinkage in the roof, I also didn't realize that the canvas shrinks unevenly, more along the length of the material than across it.  Something to be conscious of next time.
Now that I think of it,  I doubt that I could plan for shrinkage in any sort of exact way since the shrinkage is non-isotropic.  I suppose I could just make a roof cover uniformly oversize, then when it shrinks, regardless of whether it does it evenly or not, it would still be large enough to do the job.
For now, not having tried to it yet, I am leaning toward pre-shrinking the canvas.  Unroll however much canvas I need, hose it down, dry it in the sun, then cut it up and sew it into whatever shape I need. Everything I haven't tried yet sounds like a good idea.  Whether it actually is, doing it will tell.
Meanwhile, some before and after shrunken roof cover pictures.
Before: the yurt roof cover on its maiden voyage in Kings Canyon National Park. I trimmed the fabric so there would be about 8 inches of overhang.  Sewing the seam at the edge reduced that by about an inch.  Other than the wrinkles which I hadn't dealt with yet, not bad.
After: Overhang of the roof fabric has been reduced to about 4 inches at the max and two inches at the minimum.  The wall fabric likewise has shrunk some top to bottom and side to side. Time to make some corrections. Canvas work is not an exact science.

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