How to Inspect and Specify
PVC and Mesh Bookbags
1. Always check the thickness of the PVC. The thicker, the better! Most PVC bags are between 10-14 gauge (Nike clear bags are 14 gauge) and the best ones, like ours, are at least 20 gauge thick PVC.
2. The simple way to check PVC thickness is to fold the clear plastic accordion-style three times. If you can do this easily, or if the clear PVC creases easily, then don?t even consider the bag.
3. Look for bags that are 100% transparent from all sides. (Dark mesh or semi-opaque PVC defeats the purpose of having see-through backpacks in the first place.)
4. Check the top seam. If the shoulder straps and hanging loop are all stitched into the same place at the top seam, then this is the first place that the bag will fall apart.
5. Look for double stitching for all load-bearing seams. The seams and joints are where most of the cheaper bags fail because they aren't properly reinforced at the stress points. Any cut, tear or unusual stress can pop any single point on a single- stitch bag and this will eventually tear out your entire seam.
6. Demand that 100% nylon thread be used, and not cotton or cotton/poly thread. The simple test of thread type is to open the seam and hold it up to the light so that you can look down along the stitches. If the thread is fuzzy, like an angora sweater, then they are using cotton-based thread in the manufacturing. Cotton thread shreds and tears too easily for use in backpacks, and should be avoided.
7. Make sure that the bags will carry the weight that will be put in them! Fill the backpack with books and make sure that the weight of the bags will be borne by the bag's seams or webbing reinforcements, and not by the vinyl itself.
8. For mesh bags, judge the mesh opaqueness by placing a text book inside and stepping back 10 feet. If you can read the cover, then you can deem the bag ?transparent.?
9. For mesh bags, take a pencil and attempt to poke it through the holes in the mesh. If the pencil moves the mesh aside and goes through easily, then the mesh isn?t doing its job (this test will not work if the mesh holes are larger than pencils to begin with). The best mesh backpacks will break the pencil before they allow it through.
10. Finally, look for the warranty. A company that promotes a bag without a warranty is working for their benefit and not for yours.
Bags must be guaranteed to hold up in weather extremes from ?30?F to 120?F.
Only 100% nylon thread may be used in manufacture of PVC bags.
All load-bearing seams must be double-stitched.
Bags must have a 3-Year Warranty
PVC gauge must be 20 gauge (5 mil) or thicker.
Mesh bags samples will be judged for opaqueness, size, durability and size of holes.
Specifications to Use when looking for competitive bids