First real chance I have had to look at some old posts since joining here, great work!
I blasted some mdf for interior work a long time ago, several years back and got a similar effect with my little blaster pot. The set up had to work hard to cut into the medex and so you got this crater effect, my large system I have today you can vary so much.
The Grain-Fraim maybe really well made over engineered as most US products but I thought at $500 for a frame with loads of wires going over it, I could make my own, and I did, and using conventional garden wire, if they break or get malformed it all adds to a more interesting and less uniform pattern in the background. I have found all signs I have seen with the Grain-Fraim look abit too mechanical, abit like some routed stuff….just just me though.
Great job though, and would be really interested to know more about life expectancy of Ext. MDF outside.
Have heard some horror stories in the US, but signmakers in the UK seem to love it, I guess its all down to rounded edges and good paint preparation.