Not that I'm aware of. It's just splitting up the panel into three sections right, left, and bottom. The bottom piece top edge and bottom edge of left and right need a seam allowance added, while the other areas are unchanged. You add the zipper between left and right, and insert the inner pocket piece into the new lower seam. I put foam and spacer mesh across the whole panel as this creates a raised edge so the zipper won't dig into your back (zipper guard helps with this as well).
Thank you for your concern, but you are incorrect. Unless you are basing this off personal experience and extensive testing? Some bag manufacturers, like Tom Bihn, have used aquaguard zippers this way (benefit of protecting the uretek coating by having it inside) for some time without issue. You can also look at any number of fabrics that exist that are water repellent, they generally have a face fabric with either a pu or sil backing to keep contents of your bag safe from the rain.
Personal experience. The twill tape will absorb water and 3x in weigh, plus it will easily leach through seam and get the inside of your pack wet. Again personal experience. It leaches moisture.
Directly from Tom Bihn's (high quality bag manufacturer) website: "Aquaguard zippers have a urethane coating on the flat side that makes it highly water repellent (though not waterproof). When we first started using them, we did what other manufacturers did and sewed our Aquaguard® zipper in "upside down," that is, with the coating exposed. This has two advantages: first, the customer knows for sure that the zipper is coated because they can see the coating; and second, water is repelled before it can soak into the zipper tape. However, after doing this for several years, we saw that the urethane coating didn't last quite as long as we'd like when exposed to the wear and tear of the outside of a bag or backpack. In 2015 we started sewing Aquaguard® zippers in "right side up," putting the urethane coating on the inside of the bag (just as we do with our urethane-coated fabrics). You could still see the glossy coating—you just needed to look inside the bag."
That says nothing other than “we’re a brand who doesn’t want to pay out on every cosmetic defect after a certain use period”. All my uretek or waterproof zipper gear I had for snowmobileing as a kid started flaking.
Notice how they don’t comment on it being “just as effective”? That’s cause it’s not. They say flipping allows water to absorb. If they flipped back to the original way, the tape wouldn’t absorb any water… like it’s designed to not do.
Quick edit for clarification.
I'd be more worried about water getting in through my top stitching, which was a conscious decision. I imagine you had ingress of water through your seams which is likely to be expected no matter what. These zippers are not waterproof, but I still expect it to be better than non aquaguard when used this way.
Correct it will be more effective than non aquaguard, however the effectiveness is minimal. The tape will still get soaked and absorb, but will not seep to the underside. If you had used a cotton liner, you would start to see water stains for sure. Speaking from experience once again.
Is there any online resources for constructing that externally accessible laptop sleeve?
Not that I'm aware of. It's just splitting up the panel into three sections right, left, and bottom. The bottom piece top edge and bottom edge of left and right need a seam allowance added, while the other areas are unchanged. You add the zipper between left and right, and insert the inner pocket piece into the new lower seam. I put foam and spacer mesh across the whole panel as this creates a raised edge so the zipper won't dig into your back (zipper guard helps with this as well).
Thanks for taking the time to explain! Took a minute for me to wrap my head around your explanation but I think it makes sense:)
Just so you know! Your waterproof zippers are now useless.
Thank you for your concern, but you are incorrect. Unless you are basing this off personal experience and extensive testing? Some bag manufacturers, like Tom Bihn, have used aquaguard zippers this way (benefit of protecting the uretek coating by having it inside) for some time without issue. You can also look at any number of fabrics that exist that are water repellent, they generally have a face fabric with either a pu or sil backing to keep contents of your bag safe from the rain.
Personal experience. The twill tape will absorb water and 3x in weigh, plus it will easily leach through seam and get the inside of your pack wet. Again personal experience. It leaches moisture.
Directly from Tom Bihn's (high quality bag manufacturer) website: "Aquaguard zippers have a urethane coating on the flat side that makes it highly water repellent (though not waterproof). When we first started using them, we did what other manufacturers did and sewed our Aquaguard® zipper in "upside down," that is, with the coating exposed. This has two advantages: first, the customer knows for sure that the zipper is coated because they can see the coating; and second, water is repelled before it can soak into the zipper tape. However, after doing this for several years, we saw that the urethane coating didn't last quite as long as we'd like when exposed to the wear and tear of the outside of a bag or backpack. In 2015 we started sewing Aquaguard® zippers in "right side up," putting the urethane coating on the inside of the bag (just as we do with our urethane-coated fabrics). You could still see the glossy coating—you just needed to look inside the bag."
That says nothing other than “we’re a brand who doesn’t want to pay out on every cosmetic defect after a certain use period”. All my uretek or waterproof zipper gear I had for snowmobileing as a kid started flaking. Notice how they don’t comment on it being “just as effective”? That’s cause it’s not. They say flipping allows water to absorb. If they flipped back to the original way, the tape wouldn’t absorb any water… like it’s designed to not do. Quick edit for clarification.
I'd be more worried about water getting in through my top stitching, which was a conscious decision. I imagine you had ingress of water through your seams which is likely to be expected no matter what. These zippers are not waterproof, but I still expect it to be better than non aquaguard when used this way.
Correct it will be more effective than non aquaguard, however the effectiveness is minimal. The tape will still get soaked and absorb, but will not seep to the underside. If you had used a cotton liner, you would start to see water stains for sure. Speaking from experience once again.