Shiny stones?

[John Noell]

A friend wants me to engrave some highly polished stone key fobs he found. They are made from turquentine, carnelian, green aventurine, blue agate, honey jade, and hematite. Has anyone tried such stones - and if so, how do they engrave. (He only has one of each so I am concerned about ruining them. Start low in power/high in speed and work my way up?)

[Mike Null]

I haven't attempted to engrave any of those stones but on the ones I have tried the laser ablated the surface slightly without achieving any depth. The mark was visible but not particularly attractive. More power isn't the answer either as you could possibly overheat and crack the stones.

[Darren Null]

Work your way up, yes. Not those particular stones, but stones in general, I've found you only go in a certain depth before the stone starts melting.

You can get a better depth by cleaning the dust from the bottom of your burn and repeatedly lasering, cleaning at each stage. But it takes ages; isn't cost-effective, and requires that the stone doesn't move, or that you can get it back in exactly the same place each time.

[Dee Gallo]

I've done some stone (jadite) and found the best results are from darker colors, since the laser leaves a white mark and not very deep at 100 power/40 speed on my 25 laser. But it looks very nice especially if you avoid stones with veining. Two passes will give you a better job.

These are only one pass, and the pieces are about 1 1/2" x 3/4". I have not tried it on my 35 so I can't tell you if there's a difference. Probably not.

Hope this helps, dee

PS- I should add that the lased images are actually sharp, unlike my photography skills!

[Doug Bergstrom]

We have done stones similar to Dee. They look great but try to stay with darker areas and less veining to get good results.

[John Noell]

Thanks for the tips. These are circular (about 30mm diameter) and thin (maybe 2.5 mm in centre) with a hole drilled through from one edge to the other (they spin on a wire through the centre). I am very afraid that they will be easy to crack. The guy insists I try so when he come back today I guess I'll do it.

[Dee Gallo]

John, take some pictures when you're done! I'm interested to see how other types of stone react to the laser. Could open some doors!

thanks, dee

[John Noell]

The worst part of this job was the poor logo (in design and quality) the client insisted on using. I only managed to grab two pics before he grabbed the rest and drove off (happy with what he got). Each type of stone responded rather differently. The green aventurine was the worst. The other side came out better (using a simpler design). The blue agate was about in the middle pf the pack. The turquentine came out rather well. The carnelian was perfect! Crisp white logo and text. It is wonderful stuff to work with! The hematite marked very little, even with several passes but the client loved it and asked for his name to be put on the other side of the stone. I talked him out of even trying the honey jad as it was light in colour and had white veins. Hope I don't see this kind of job again for a long while!

[Bill Cunningham]

Here's a few I've tried
ApachieTear
A arrowhead of some kind (can't remember the type of stone)
Calcite
and Hemitite(sp?) in the link below
http://www.sawmillcreek.org/attachme...1&d=1208484576

[Roy Nicholson]

Frank got me to try some RubnBuff on a photograsph the other day and it came up 100%

I'll be trying it far more often in the future.


Regards


Roy N.

[John Noell]

Looks like hematite in the middle. That's about the same type of mark we got. I would have tried some rub n' buff but the client was in a hurry.

[Chris Hanson]

The arrowhead looks to be obsidian (I have done some flintknapping among my other strange hobbies). Tons of these are made in Mexico and sold in souvenir/museums shops. It is volcanic glass and so (except for more flaws) should engrave the same as commercially produced (black) glass.

[Bill Cunningham]

YUP!! Thats what it is... obsidian ...
Hematite is heavy, and looks like a silver or chromed coloured metal. It lasers to a raised image... kinda neat..

[John Noell]

YUP!! Thats what it is... obsidian ...
Hematite is heavy, and looks like a silver or chromed coloured metal. It lasers to a raised image... kinda neat..

Hmmm, now I am wondering if I didn't hit it hard enough. I only got a nice grey image. (With only a single very thin disc-shaped sample already in a mounting, with a wire through the entire diameter, I was afraid to blow it up.)

[Bill Cunningham]

When I first got my laser, I did a trip to a rock shop a few miles away, and they gave me a whole bunch of samples.. Hemitite was one of them.. I wish I had known what kind of results I would get. If i did i would have put something interesting on it.. Only had the one little piece and darned if I can remember what I hit it with.. I know it was a raster, probably about 30-40% speed 100% power..