I am inspired by God to paint "His Word". Upon opening the Bible, the first verse we read in Genesis is "in the beginning God created the heaven and the earth." What does heaven look like? There are angels.
The simplest way to clean up an oil or acrylic painting on canvas is to use a white cotton cloth soaked in a gentle soapy water; olive oil-based soap works wonders. You'll be surprised to see how much grime comes off. Be gentle with paintings with thick impasto, as you do not want to break hardened paint.