What we need to achieve is the markings that appear on the concrete in this photograph of the wood store and class A3 lorry at Thornycroft.
The joins between concrete sections that we marked into the DAS (ref: previous posting) are gently scribed with a scalpel to break through the grey and reveal the black, thus highlighting the joins.
The whole area is then gently scrubbed over with a very fine grade of emery paper to flatten brush marks and deepen the grey in places as the black begins to penetrate.
Next a stiff brush was dipped in black, wiped almost dry and lightly dabbed onto the concrete to represent dirt and grime caught in concrete imperfections.
Finally, scrapes from a black pastel stick were picked up on a dry brush and rubbed over the concrete in places for more grime especially at door entrances.
This was our first attempt at this procedure. The idea of layered paint and cutting through I remembered from a magazine article years ago.