So this is mostly a note to myself but maybe it can help others. I made various acrylic backgrounds on various materials:
Ordinary watercolour paper doesn't resist much. The illustration board (Canson) isn't doing too bad but the colours tend to disappear.
No surprise but the Fabriano canevas for acrylics is steadfast and the colours really shine. I'm not sure about the texture but it's ok.
And lastly a plyboard with Daniel Smith watercolour ground is disconcerting but intriguing. I plan to test that further. I was hoping to find the transparent one but it seems impossible to find anywhere in Europe