The ink had faded to invisibility.

　　墨水已退色看不見了。

　　The method had advantages of large capability and good invisibility.

　　該方法具有隱藏容量大和隱蔽性強(qiáng)的特點(diǎn)。

　　Simulated results show that watermark invisibility is good.

　　仿真結(jié)果表明，水印不可見性好。

　　So it's a magic potion?

　　那么，這是個(gè)神藥？

　　Use gauze to filter the decocted herbal potion.

　　用紗布過淋煎好的中藥。