Laser engraving matte silver aluminum plate

[Clyde Cochrane]

I am having a challenge laser engraving an anodized aluminum silver matte plate. It is supposed to engrave black. However, when I do, it smudges and there is a black ash that I have to wipe off with water and a rag, which dulls the black color. I have had great success with black plates that engrave silver and gold, but those are glossy finishes. This is very frustrating. I am lasing at 45% power and 100% speed on a 40W laser. I have tried higher and lower power settings and speeds, but I just can't seem to get it right. Any ideas on what I am doing wrong? I appreciate any help or guidance. Thanks

[LINUS]

It is generally known that the lase engraving machine is poor in engrave metal,especially pure metal.But I can give some tips to you to have a try.
1.You can put masking tape around the metal to prevent reflection
2.You will need the help of the “thermark spray”, you can visit www.thermark.com for more information.
Of cause,you can buy a laser marking machine .It's good at engrave directly pure metal.