How to make scratchboard art

There is very few scratchboard artists in Finland. Leena Pekkalainen is one of them. She makes black and white horse scratchings. It seems that I am the only one here who makes fully coloured scratchboard paintings.

Scratchboard or scraperboard is a technique where pictures are created using sharp tools for etching into a thin layer of white caolin clay that is coated with black ink or colourful paint. I use Ampersand claybord that I colour before srcatching. I also wash all exposed white caolin with thin layers of acrylic colours. Usually I airbrush the layer that I am going to scratch first. Next layers I paint by brush.

Some of the tools that I have tried:

I find the scalpel in left to be best tool. Brushes and needles loose their sharpnes. Blades can be changed easily. Fiberglass brush tends to take too litle or too much paint of.

Painting where scratching is well visible