I had great success engraving some off-cuts of large Black Limestone flags a while back. I was oiling them up with a beeswax / mineral oil mix first and then letting them sit for a while before engraving. Here’s a pic of one I just did (obvs the left one) and one I did a while back. The older one has faded in a bunch of places which is really disappointing. I’m not sure if excess oil has spread to those ares or what. I’ve given the older ones a scrub with soap and water but they’ve not come back to what they were at engrave. Any ideas? Do we think this is a natural ageing of the material / engrave or could I prevent it?
Here’s one of the faded piece not long after engrave.