实际操作时可以做一个倾斜测试：把产品挤在手背，倾斜手背，流动最快的先上。

需要注意的是：有些高黏度精华虽然看起来稠，但吸收后并不成膜，这类产品仍应排在乳霜之前。

判断的最终标准是是否成膜封闭，而不仅仅是外观稠度。

A practical tilt test: place the product on the back of your hand and tilt it — the one that flows fastest goes on first.

The real criterion is whether it forms an occlusive film, not merely how thick it looks.