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Sewing Sunbrella - puckering

9K views 13 replies 12 participants last post by  Rhapsody-NS27 
#1 ·
I've been making various covers, sheet bags, and other small canvas projects for several years using Sunbrella and a Singer "heavy duty" sewing machine. Usually they turn out pretty well, given my utter lack of prior knowledge and legit sewing machine.

However, I just made a pair of handrail covers and don't remember this ugly puckering ever happening. Figured maybe it was just the shape of the piece, the stiffness of the fabric, or something, and that it would smooth itself out after a few weeks in the elements.

More importantly, I don't even know if I'm using the right term: puckering? scalloping? dimpling?
Any ideas? Am I feeding the canvas in too inconsistently as I sew? Maybe the thread or needle I used this time were wrong?
These covers will do the job, but would be nice to know how to avoid this on my next project.
 

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#4 ·
Here are some links on seam pucker:

http://www.amefird.com/wp-content/uploads/2010/01/Minimizing-Seam-Puckering-2-5-10.pdf

http://www.amannusa.com/pdf/nahtkraeuslen_gb.pdf

http://www.coatsindustrial.com/en/information-hub/apparel-expertise/seam-puckering

However, seam pucker in your picture was not easy for me to see.

To better understand the impact of pucker on my machine, a Juki 1508 industrial compound walking-foot machine, I cut several 4" x 60" pieces of material, sewed seams, hems, webbing and binding, and measured the shrinkage.

For example with 6 mm stitch length:

Hem -- no pucker
Binding over raw edge -- 1" loss
Webbing over raw edge -- .5" loss
Binding webbing sewed over raw edge -- 1.25" loss

Changing the stitch length to 8 mm resulted in less pucker.
 
#8 ·
Thanks for the quick replies, everyone! That video helped. This was genuine Sunbrella fabric (ordered from Sailrite, so it better be!). I think the thread tension was okay -- nice even loops on both sides of the stitch -- and I did use a new needle, but since I didn't think perfection was required for my initial hems (I did a 1/4" hem and then folded again for a 3/4" hem on both sides to better support the snaps), I didn't pre-fold or use seam tape; instead I cheated and held the folds in place by grabbing the fabric in front of and behind the needle at the same time and "helped" feed the material through. The stitching ended up consistent in length, but in retrospect I think my hand-feeding of the material resulted in a lot of high- and low-tension spots in the fabric itself.

I'm making a mainsail cover in a few weeks, and I'll have similar, though much longer, hemmed seams. Will test doing it the right way before proceeding with that project and see if that's indeed my problem.
 
#11 ·
Assuming you're using a fresh needle, and you have balanced and properly set your upper an lower tensions, the best thing you can do as an infrequent sewist using a non-walking foot machine, is to use the double sided sticky tape.

I just completed a sailcover for my Catalina 28, using the kit from Sailrite (saves a lot of hassle, as they are pre-marked). I did it on my 1968 Kenmore domestic machine. I used the tape for all the seams, so when I got to the end of a long run, the ends were perfectly even. And, it made it easier to sew, and sew well. Bottom line is the tape goes a long way towards making amateur work look like pro work. I hotdogged it a little and used white thread on Navy Sunbrella, and it looks fabulous.

Probably already mentioned by previous poster, but longer stitches are better to avoid pucker.

There were only a couple small places in the project where the machine wasn't up to the task. Areas like corners or corners with zippers will give you trouble, so plan on resorting to just a few inches of hand sewing in these thick areas. Also, the kit comes with some leather, but doesn't specifically say where to use it. I used it at the upper opening of my cover when I had to modify the design to accommodate my mast diameter. I tried using the Kenmore to sew through the layers of Sunbrella and leather. Yeah...right. No chance. Hand sewing did the trick there, too.

If you're thinking about using the Sailrite kit, I would say that the instructions are excellent (written and dvd). Hardware's good, and zippers are good, as is the overall design. Overall, very pleased and would buy again.

Last thought: I completed the kit in the winter and waited until spring (Michigan) for the boat to be rigged and in the water before installing the fasteners at the bottom of the sail cover. Put the cover on the boat, and used masking tape to mark the points where I wanted to install the individual fasteners. That ensures that you don't end up with a fastener in a bad spot, like where the boom vang or main sheet attaches to the boom. Custom!
 
#12 ·
Assuming you're using a fresh needle, and you have balanced and properly set your upper an lower tensions, the best thing you can do as an infrequent sewist using a non-walking foot machine, is to use the double sided sticky tape.
That worked well for me too. I have a Singer Featherweight from the 1940s, no walking foot or zigzag, but using Sailrite's double-sided tape on all the seams really helped. I did a mainsail cover for my 22' boat and although there are a lot of issues with it (it's my first large sewing project) pucker isn't one of them.
 
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