I am using an Atomstack A5 M40 system, Settings for this project were Power:100%, Speed 10, Number of passes 1. The engraving was perfect. After I was finished I used Tung Oil with a foam paint brush and covered the sides and top and let air dry. I did not saturate the slate just a light finished. There was no yellowing in the etching as some has experienced. I think the yellowing is caused from the speed being to slow at 100%. I expirmented and found that to be the case.
