This effect is known as orange peel and is caused by a process known as crawling. This can often be caused or exacerbated by silicone contamination of the surface.

If you can sand the surface back with some very fine sandpaper, that might help. Alternatively, you might like to try the PERMAPRINT Premium Opaque White Ink. This has higher viscosity and would thus be less susceptible to crawling. You could also try a finer mesh so that you’re putting the ink down drier. However, you may need multiple hits to get the right film weight.

Given the variability inherent in the substrate, printing on any timber will take some experimentation, so we suggest trialling a print on a small piece of timber first.