As of this post, "raining varnish" delivers just one Google result.  The text reads, "how well I know the smell of varnish!"  From Cruises in Small Yachts and Big Canoes by Harry Fiennes Speed, 1883.

From A Family Flight Around Home, 1884.

Here's an April fool caught in a shower, from St. Nicholas magazine, 1903.

From Voyage aux Pyrénées by Hippolyte Adolphe Taine and illustrated by Gustave Doré, 1860.