Thanks George,
I did have a go today and burnt 2 on opposite sides of the same mat. I used the default feeds and speeds on one and lowered the speed to 800 on the other. Pic_1 was the default and shows the white line and Pic_2 was etched at 800 and shows an embossed 'drain pipe' that is very cute. I will see what the committee think whenever we are allowed to meet again.
I also did another double sided mat with a mandala bunny, Pic_3 shows the result from sitting on the wire frame and is quite black and crisp, Pic_4 is the result after raising the mat 3mm and is a bit brown and not as crisp.
It was rather a good day today so I got a bit more sun time than shed time.
take care
Don W
PS I am going to try and etch a picture tomorrow.