Because oil is like a lock moisture barrier, if this layer protective film disappears, then the water will soon be air-dry the external environment.

因为油脂犹如锁住水分的一道屏障，如果这层保护膜消失不见，那么，水分很快会被外界环境风干。

youdao

youdao

Ozone forms a protective layer between 12 and 30 miles above the Earth's surface.

臭氧在距地球表面12至30英里的地方形成一个保护层。

《柯林斯英汉双解大词典》

As you can tell, the device itself is encased in a ShockMount layer of protective armor, and we have to stress the "armor" aspect.

ENGADGET: Ridgid Jobsite iPod Radio takes a beating, survives long enough to go on sale (video)

In the past few years players have started to wear this layer of protective gear meant to feel like a second-skin in a sport that has bigger, faster and stronger athletes than ever.

CNN: March Madness, this year with more padding

Piers, jetties and seawalls with a protective layer of marine growth absorb wave action better.

FORBES: Women Show Construction Industry How to Rebuild Better, Stronger