Good question.
Basically, eVENT is a PTFE (teflon, ie: plumbers tape) membrane laminated to a face fabric.
Gore-Tex was the world's first company to use PTFE in a waterproof breathable. But, their patent ran out a few years ago, and other smaller companies jumped on the proverbial bandwagon and started using PTFE as well.
Both are exceptional fabrics. The only drawback of using a microporous laminate or coating is the garment's complete reliance on the DWR. Once the DWR wears off, and the face fabric becomes saturated, the garment stops breathing. This is why W.L. Gore and all the other microporous garment manufacturers are so adament about keeping the DWR in top condition.
The other route is a MVT (non-pomeric) coating, which doesn't have any pores. MVT's use two diametrically opposite layers, one is hydrophillic (water loving) and the other is hydrophobic. (water hating) Water vapour produced by the wearers body is 'picked up' by the hydrophillic layer, and the hydrophobic layer 'grabs' the vapour and tosses it outside of the garment.
Microporous fabrics are much more breathable, but MVT fabrics are not at all reliant on a DWR.
So you have to pick which road you want. However, companies like Helly Hansen use both technologies combined into one garment. 'Helly Tech.'
There's one other drawback to using a laminate/coated fabric. They don't breathe in below freezing temperatures. This is why countries like Sweden and Norway use cotton as an outer layer in the cold, cotton is unaffected by temperature drops.
Adam
