Lasering a mirror

[Bert Kemp]

Show off LOL beautiful Bill wish I could do that.

I've done lots of photographs on mirror, and always engrave and colour from the backAttachment 301777

[Mike Audleman]

I can't think of a single reason I would engrave a mirror from the front, although there are probably a few. That's just my opinion of which you'll find many here. So follow the earlier advice and buy the cheap mirrors and do some testing.

I can think of a few. First, you can frost the glass to form decorative accents on corners and edges. This provides a 3 dimensional look to the accents where the rear engraving would be very flat looking. Second, is wanting to light the effect. You can edge light the glass (mirror) that has been front engraved so that the "frosted" sections will light up. To get the same effect by rear engraving, you would have to engrave through the mirror coating as well as into the rear glass surface or engrave through the mirror coating and then apply an LGA behind the mirror.

But for this apparent project, i agree with the double reflections issue of front etching.

First or second surface mirrors Matt?

cheers

Dave

I would be surprised to find a front surface mirror used in a project like this.

[Charlie Hawkins]

I was given a bunch of mirrors out of projection TV's, and the fellow said I may be able to use them for engraving wth my Epilog Summit. They are double-sided mirrors, however, and have no 'coating' like one-sided mirrors do. I did try a smaller one that fit in my engraver, and it did a glass-type etching on the mirror glass... however, the other side didn't engrave at ALL! Are these a special type of mirror, and has anyone ever used these for engraving? I am not sure what you all use to mask the mirrors, either. The side that did engrave, had small 'shards' of glass left on the surface (very small particles), and is this normal also? I am in need of knowledge on this, as I am not sure about these mirrors. I have had a lot of fun engraving granite tiles so far, and am enjoying my EPILOG Summit very much!! Thanks!
Charlie

[Bert Kemp]

Charlie I have no idea what type of mirrors these are but the side your engraving leaving the shards is normal, you can cut your power down some to reduce this, but you are fracturing the surface and it results in tiny pieces of glass.

I was given a bunch of mirrors out of projection TV's, and the fellow said I may be able to use them for engraving wth my Epilog Summit. They are double-sided mirrors, however, and have no 'coating' like one-sided mirrors do. I did try a smaller one that fit in my engraver, and it did a glass-type etching on the mirror glass... however, the other side didn't engrave at ALL! Are these a special type of mirror, and has anyone ever used these for engraving? I am not sure what you all use to mask the mirrors, either. The side that did engrave, had small 'shards' of glass left on the surface (very small particles), and is this normal also? I am in need of knowledge on this, as I am not sure about these mirrors. I have had a lot of fun engraving granite tiles so far, and am enjoying my EPILOG Summit very much!! Thanks!
Charlie

[Nancy Laird]

Hi, all. Just getting back into SMC and reading up on past laser questions. As far as engraving glass is concerned, if you are engraving flat, from front or back, make sure your piece is stable, and ENGRAVE IT TWICE. As soon as the first pass is finished, just press the button to do it again. The second pass removes most of the glass bits and removes those bits that didn't get knocked out the first time. We do glass for flag boxes and always engrave in reverse, and running it twice makes it look like it has been sand-blasted. Just our experience.

[Mike Audleman]

They sound like first surface mirrors. This is common in projection systems. The side you engraved is actually the back of the mirror. Its the side with the glass. The other side is what the TV used not the side you etched. The reason your laser didn't touch the second side is, well, its a mirror! The light bounced off as it should have. I don't know any way other than applying some sort of material to it to etch on that side. Tape, masking spray, anything that will absorb the IR from the laser.

The reason for this style of mirror in a projection system is so that the image is not doubled. A standard second surface mirror (typical bathroom mirror) actually casts two reflections! Take a standard bathroom mirror and lay it flat on a counter. Set a pill bottle or other upright object on top. Now get down at an angle (45 or so) and look at the base of the object and its reflection. You will see two reflections! One is coming from the silvered surface on the back of the glass. The other is coming from the front surface of the glass. The thicker the mirror glass, the more obvious this second image will be and the farther it will be separated from the main reflection. This is why typical mirrors are made from the thinnest glass possible, it reduces the offset of the second reflection.

Now take one of your projection mirrors. Set it on the counter and put another pill bottle on it and look at it from the same angle. You will see only one reflection. That is because the silvering (aluminum usually) is on the TOP of the glass, not the back. Since light does not pass through the glass to get to the silvering, there is no second reflection. If you see two reflections like the bathroom mirror, you are looking at the BACK of the projection mirror, not the front!

Here is a photo I took with objects sitting on top of a standard second surface mirror.

Look in the lower left at the reflection. Notice there is a second fainter reflection offset from the brighter first. That is because the glass and the silver both reflected the light.

[Charlie Hawkins]

Hey thanks for the tip on engraving twice to get rid of the shards1 And, the first surface mirrors is something I had not heard of before, but it makes sense. I am at a loss as to how i could get good results from these mirrors, as I have seen on here. I don't know if there is any way to engrave through that surface, as it is metal of some kind, I believe...