Although it is certainly not a must, we recommend that you seam seal your X-Pac® project for a few reasons.
First, every time your sewing needle penetrates the fabric, you create a place for water and moisture to pass through. Repeat that hole-punch several hundred times and you've got a LOT of places for water to seep in. Proper seam sealing will close all of those little needle holes and make sure the items inside stay dry.
Second, seam sealers help strengthen the stitches by acting as a bonding agent that holds everything together - sort of like glue. Some people worry about the additional weight of seam sealant, but this is often negligible.
Lastly, to further standardize things, we put the same amount of stuff in each sack. We even matched the number of rolls for the roll-top closure.
Finally, it was time to make it rain!
Putting the stuff sacks through a rigorous test was important to us. Simply testing water resistance wouldn’t tell the whole story. That said, we chose to completely submerge the stuff sacks to stress the seams as much as possible.
Silicone Sealed Stuff Sack
The silicone-sealed stuff sack was noticeably damp on the inside, but not sopping wet or dripping. Also, no water had pooled in the bottom. But yeah, it was a far cry from a "dry" bag.
From what we could tell, most of the moisture was near the bottom of the sack. For that reason, we think that water probably entered through the bottom seam. When we sealed the bag, we made sure to seal on the top, bottom, and in between the panels knowing that this might happen.
Overall, we give the silicone seam sealer a grade of "C". It kept the items mostly dry, but not entirely.
DCF Repair Tape Sack
If the silicone seam sealer got a C, then the DCF® repair tape got a C+.
It was also noticeably damp on the inside, but again, none of the fabrics were soaked. There also appeared to be less moisture overall within the sack as compared to the silicone-sealed test.
Interestingly, it appeared that the water was more prevalent on the upper half of the bag. Most likely entering through the closure or the roll top seams.
But once again, not good enough to be a dry bag.
Although neither system worked as well as we hoped, we still recommend that you seal your X-Pac® projects. The test that we ran on the bags was far more rigorous than what most people will see. We believe that if these bags were just exposed to rain or a brief submersion, they would have been totally fine.
The most important piece to remember when seam sealing is to cover all important seams. If you’re taping, ensure your margins are small enough to tape over comfortably. If you’re sealing, then make sure you apply the gel in all areas needed, (i.e. between panels).
After all, a bag with good water resistance is better than a bag with no water resistance.
Lastly, be sure to stay tuned as we plan to continue this testing in future articles with new methods and sealants. The seam sealing search continues...
March 04, 2021
Silicone seam sealant is for silicone fabrics, so is a poor test for XPAC? Surely seam grip is a better choice, as it sticks well to anything but silicone fabrics.