Hard Marble

[Joe Motley]

I have been using the black 6x6 hard marble from LaserSketch for garden markers, pet memorials, people memorials, etc., obviously for outdoor use. A customer recently brought one back because something from the white engraved areas seems to be leaching out onto the black surface. The shiny black surface seems to fade pretty quickly, too, becoming splotchy. Have tried washing, polishing, etc. The surface seems to be permanently marred. Visited a cemetery this AM where some of our markers are and found the same thing.
I called LaserSketch yesterday and they said they had never heard of such problems.
Any ideas will be much appreciated. Thanks

[Martin Boekers]

I have heard that a test to distinguise granite from marble is to put a bit of acit (citrus juice, vinager etc) and it will ruin the surface of marble.
The granite it won't effect.

Is there a chance the area where these are has a higher content of such acid in the rain it could affect it?

It seems most use granite for outdoor usage, I know that granite wears better than marble.

Someone with more experiece maybe able to help.

[Dee Gallo]

I've only used black granite for outdoor use, since others said marble is not very weather proof. I have one marker that's been out for 3 years, in rain and snow and even buried by a digging woodchuck (grrrr) and uncovered again... with no visible change. I have other tiles in places which are mopped regularly and never had a complaint of wear. I'd guess your material is not the right thing for outdoor use, no matter what LaserSketch says...

Check with Belinda, she knows all about the dye processes they use on marble, which might explain the leaching.

I got my granite from Home Depot.

:) dee

[Joe Motley]

Dee, Thanks for your response. I have an epilog mini 40w and am currently experimenting with settings for granite. May I ask about the settings you would recommend? Thanks, Joe

[Dee Gallo]

Joe,

I use 100 speed/25 power/600 dpi ... but that might have to be tweaked depending on the job. I took a sample tile and did a series of tests to find the right settings for my laser and for future reference. You should too. You don't tell us in your sig what laser or power you are dealing with, so my settings may be completely wrong for you.

cheers, dee

[Larry Bratton]

Epilog 40watt here...granite...100s 38-40 power at 300dpi.
Be careful with that stuff from Laserbits. He sells a product he calls absolute black MARBLE..it ain't marble. I use it, I tested it with acid ( vinegar )and it absolutely will not marr it. It is some type of granite, I engrave it using those settings I just gave you and it works great. Not saying it's a bad product or anything, it's just not marble. Marble is a lot softer too. When I engrave marble, I can literally get enough depth in text to put a good fill in it..not so with this stuff.

[Dan Hintz]

Agree with Larry... what he sells is definitely a fine-grained granite, not marble, despite the name.

One possibility (and I would suggest speaking with Belinda about this) is the stuff was dyed and the dye is now leaching.

[Bill Cunningham]

If it is real marble, you probably wont be able to etch it clearly using granite settings.. On Real marble, I use 35 speed, 100 power @ 600 dpi, and sometimes go over it twice to brighten it up. Marble turns white when engraved and needs no whiteners as granite does. But don't use it out side, even if sealed. The laser sketch 'marble' is granite, and excellent for out side use. It's just a much finer grain than the pieces they sell as granite. I use exactly the same setting for both of these lasersketch products. and they both have to be whitened for maximum brightness.

[Larry Bratton]

what Bill said and use Winton's oil based artists paint to whiten it. Rub it into the whole thing and it's like magic when you buff it off. To quote Bill "it makes it pop off the rock"