Here is another guest post by Paul. "The Thief" reader Justin left a comment on Paul's first post: "Big thanks to you Paul for sharing your experience! Always been a huge admirer of the film and Errol's other work... So could you say more about the "bath" and the specific process/ materials you'd use to make one of the BG's?"
Here is Paul's reply: "A lot of Errol's backgrounds were in the film. I think he did the Lion Fountain sequence, a lot of the market stalls, the atmospheric distant hills, the city behind Yum Yum's beautifully rendered roses, and a lot of the War Machine. I never met him, so I don't know too much about his techniques, but I was told he often put his backgrounds in a bath. I tried this with the Zig Zag tower background which had a sort of milky sky. Dick wanted more stars in the sky and the city outside the window more "magical," and he gave me some Edmund Dulac photocopies from "The Arabian Nights" and "The Rubaiyat of Omar Khyyam," as well as some photocopies of Persian miniatures. There was always a lot of reference to look at.
Anyway, I must have dipped the background in the bath half a dozen times,taking it out of the water, adding more blues and greys, and trying to feather out the "tide lines" with a soft brush. Gradually the sky became fuller and milkier, so I put the stars on and John made them twinkle under the camera.
We usually used gouache for the skies as the chalk in the gouache got rid of a lot of the streakiness that sometimes happens if you do a wash with watercolours. However, watercolour washes were used for lots of the really dark backgrounds and gently airbrushed on top to hide any streaks. Generally we tried not to use airbrushing. Some watercolours really stain the paper and you can get a really intense dark effect, e.g. for the Camp of the One Eyes and in the War Machine. Some people were naturally more suited to certain scenes and we each tended to get whole sequences of those scenes. Some of the skies were absolutely flat, some a vignette of two colours and some milky and cloudy. Sometimes spiralling Persian miniature clouds floated by. That looked great on a flat sky. When the grey Polo Scene sky met the peacock blue "beauteous evening" sky Dick stuck a rainbow effect in to hide the join. It worked perfectly.
Anyway, the idea of dipping the backgrounds into a bath was that some of the colours floated off and some remained on the paper (we used watercolour paper, not illustration board.) It made everything look richer, like an underpainting for an oil painting. For rocky scenes, (e.g. in Tack's cell,) you can get a good craggy effect by dabbing randomly with a paper towel after wetting the bg. Then put more colours on and keep doing it 'til it looks rocky. There was often a slight grainy effect of the waterclour on the paper which you often see in the Dulac illustrations. If we had used acrylic animation paints it wouldn't have had the same lightness with the paper being part of everything and adding atmosphere. I guess all this is kind of stating the obvious, but if this is in some way useful then so be it!
Anyway, it was areal privilege to have had the opportunity to work on The Thief. Absolutely."