DyNA Evo – Safely Heating Grilamid

After a season of use my DyNA Evo liners developed significant wear above the instep at the ankle. The wear on one liner almost left the lower shell sticking through the liner. I even wore right through the supplied liner patch. This wear made it impossible to tighten the lower buckle for a good fit without significant discomfort. Upon closer inspection I noticed that just above the ankle the inside edge of the lower shell curved inward instead of having a slight flare back towards or slightly past vertical as was done on the outside of the boot. The TLT5 shell doesn’t have this issue as the lower shell extends higher than that of the Evo.

Area of Excessive Wear and Ankle Pressure Highlighted

Area of Excessive Wear and Ankle Pressure Highlighted

With a little guidance on a safe temperature to use to shape the Grilamid, I brought out the heat gun. I also had access to a FLIR camera and was able to closely monitor the actual temperature of the Grilamid nylon as well as the metal rivets that were close by. Needless to say I didn’t want to render my boots useless! Alternatively, IR thermometers are pretty common and affordable and could be used as a substitute. The temporal thermometer I own has a mode to measure surface temp.

FLIR Scan Taken While Heating Evo Lower Shell

Forward Looking Infrared Scan Taken While Heating Evo Lower Shell

I focused the heat gun stream at the offending area and alternated sides every so often. Above 220*F (I didn’t get an exact measurement but 220-250 is ballpark) the shell became pliable and I carefully sculpted the area so that it would no longer dig in when I tightened the lower buckle. Once I obtained the desired shape, I used a quick spray of water to cool the shell and make the shape permanent. Hopefully this fix will solve my discomfort and reduce wear on the liners.

Shell After Modification

Shell After Modification: Flares Outward to Limit Pressure on Ankle and Liner Wear

I forgot to take a picture of the shells prior to modification but I will try to get a side-by-side comparison.

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