Hi everybody,
For several Times I try to engrave mirrors. Everybody Time, with différent sort of mirrors, i have some bands paler on some areas like un this photo.
Have you an Idea from where it could Come from?
Settings speed 1000, full power, lpi 265.
just guessing but is there any chance that was a spot where cleaning had streak on the mirror possibly imperceptibly but still had to be burned off by the laser?
Moved to the BTM category since we’ll be talking about settings.
Are the bands always in the same place in the engrave?
What kind of file is it that you are engraving? Is it made of filled vector paths/shapes or is it a bitmap? If a bitmap, what kind. JPEGs can have odd artifacts in them sometimes. If it is a bitmap that you are engraving, have you opened it in a raster art editor and examined it?
These are the most common issues with odd effects in engravings.
I don’t know. I should try with the same sort of mirror and see if so.
For the cleaning hypothesis, I didn’t clean the mirror before putting masking tape and lasering. And bands were there before cleaning after engraving. So I dont know, It could be a cleaning in the manufacture.
So to be continued…
It looks like you’re engraving the front of the glass(?) mirror. Cleaning solution shouldnt cause too much of an issue, but you never know.
If you’re engraving onto glass and seeing that sort of variation… I’d suspect the art, like @marmak3261 mentioned. If you upload the art file we can take a look, or if you know your way around curves, i’d take a look at the histogram and see if you have any weird dips or peaks in the colors, which might indicate a variation in what you’re seeing as “black”. (You are working in a black and white raster image, yes?)
You also don’t say in your settings what mode you’re using. 3d engrave (aka vary power) or dots or what.
Anyway, I’m already way into speculation here, you need to provide a little more info for us to really be of any help now.
I have engrave from a svg file I made. So I don t think it could have colour differences. I m not very familiar with engraving and so I don t see any possibility to choose 3D or point engraving (that’s maybe for png files?).
Here is the file from a company logo 
Yeah SVG files don’t give you 3d options, they are either engraved or not, there’s no variation inside. The color thing was only applicable to a raster image.
This is a glass mirror? The glass isn’t coated? The mirror is perfectly flat? Do you see banding if you do a test engrave on a piece of wood? If you do, are the bands in the same place?
Are you reversing the design and engraving from the back?
May I suggest doing a test engrave on a piece of flat proofgrade to see if you get the banding? It would help narrow down if it’s a file or material issue. If you are engraving on the back of the mirror I’d guess the coating on back isn’t perfectly even.
No I have engraved the “reflecting side” of the mirror but I should try the opposite as you advise.
I don’t have noticed this defect on wood engrave for the moment. That’s why I don’t have put my message on “problem and support”. I guess it is more an method or material issue.
To summarize,
So thanks a lot for your help and suggestions. I will let you know the results. Hae a good day
So tests results:
So I think the problem is on materials. And the solution to engrave the back is good. I should have though about it. And so thanks for your help!!!
Thanks for posting your findings, it’ll help others. Glad you were able to sort it out.
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