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Darryl Keil
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Carl, I suspect you have a leak somewhere along the seam, since when you put curved work in the bag the seams probably do not lay flat like they do with only the platen. The other possibility is there is a hole in the surface of the bag which show up only when the form is in the bag. When the bag is flat the hole gets sealed up onto the platen. My first guess is a seam leak though.One thing about vinyl bags is they are inherently weak at the seams especially on curved work. Vinyl bags transfer all their stress to the seams and the seams start to thin out at the inside edge of the heat weld. You can get 4 or 5 years out of a vinyl bag or less than a year, depends on how they are treated and what's done in them. Although they are considerably more expensive Polyurethane bags never have this problem. In twelve years of offering Polyurethane we have never had a seam tear. You may want to consider this material on your next bag. Polyurethane comes with a 5 year seam warranty.An additional idea for finding your leak is to soak a sponge with colored water and place it on the suspected area while the bag is under vacuum, preferably with the curved form in the bag. The colored water should be sucked through at this point showing you where the leak is.SincerelyDarryl Keil: When I test my bag, with only a platen, I pull 20 inches Hg in about : 1 minute. With a curved form in the bag, I can not get a vacuum. : I recently had to repair a tear. It was 3 inches long. On the seam : ridge where the bag pieces were joined. i.e. the little hump 1/2" : from the edge. This is my 3rd repair in 4 years on this bag, and I : believe I did an excellent job with the repair. : Does this sound like a leak? I tried looking for a leak with soapy : water, but did not think to color it. Any other suggestions?: Thanks, Carl
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