Ampersand clay board in test

Some scratchboard artists have had problems with their scratchboards when humidity is very high. Since every artist do what, that their work will tolerate normal conditions.

I use nowadays only Ampersand claybords as surface for my paintings. I decided to test these hardboards that are covered with thin layer of kaolin clay. I have this ruined incomplete painting available for testing. It was more than 3 months in bathroom next to steamy sauna. Humidity varied weekly from 20% to 100% and temperature from +20 °C up to +35 °C.

After this kind of treatment I was prepared to see some damage, but I could not find anything!