Whitewash is one of those old-fashioned products we here about but never get to use. A trip overseas to the Greek Isles and you get to see whitewash everywhere. Every house is whitewashed. The only time we get to see it is when we scrape off flaking paint that was painted over calcimine without proper sealing. Up till the 1930's whitewash (calcimine, or often called distemper for inside work) was the main paint used on masonry and plaster. Thankfully it went out of favor.
Of course, with the return of "earthy" building designs whitewash is making a comeback. Special "Limewash" paints are now sold at a higher price than the best acrylic paint, and on brickwork the coverage is minute. Mind you, we don't have to finance the life-style of some marketing-mogul. It's as easy as a wink to make with an all up cost of around $1.50 a liter. Take one bucket of rock lime (sometimes called fro lime for inside work) add a couple of handfuls of Casine glue (skim milk powder), mix in a drum, add water, watch it boil - and don't touch it. Let it stand for a few days. Add your oxide color for a tint, and there it is.
Now whitewash is one of those products with a rather long use - from the Egyptian pyramids to Roman frescoes. And believe it or not, in the Bible it's a kind of swear word. Paul the apostle called Ananias the High Priest a "whitewashed wall". Jesus called the religious authorities of his day, "whitewashed tombs". These may not seem strong character slurs, but they are indeed very strong. Them there are frighten words!
Chapter 13 of the book of Ezra has most of the references to whitewash. They refer to whitewashed walls. These are walls roughly built and then covered over with a thick coat of whitewash to hide the lousy work. Yes indeed, we all know about shoddy workmanship hidden by a thick coat of paint. Ezra's point is that the people of God in his day had built their lives out of rubble and then plastered it over with religious whitewash. They were hypocrites, godly do-gooders on the outside, but rotten on the inside. Just as a rubble wall will easily fall over, even though it may look good, so will the life of a hypocrite.
So that was the thrust of Paul's insult to Ananias and of Jesus' insult to the churchies of his day. They were "whitewashed tombs", clean and white on the outside, but rotten inside. No good dabbing a bit of whitewash on a rubble wall. How then can our lives stand before the one who sees through the whitewash? It can't unless we put on the "white robe" Jesus freely gives.