JDS Mirrored Plaques

[Brian Robison]

I ordered a couple of the mirrored plaques. One is clear and one is black. Any one laser any of these yet?
Stupid question but, I reverse engrave these, right?:confused:

[James & Zelma Litzmann]

We have, but from the front, not the back. They look great when engraved. They don't last long in our showroom.

Zelma (Psalm 18:2)

[Frank Corker]

Hi Brian, the mirrored will not show if you engrave from behind, it's the front I'm afraid. They are usually black and when you see the photographs of them they look fantastic, my personal experience of doing them was that I wished I hadn't bothered. Only reason being is that they recommend you use rub'n'buff to get the finish and over large surfaces it's a bugger to get even.

[Frank Corker]

http://www.sawmillcreek.org/attachment.php?attachmentid=61188&d=1174983164

[Brian Robison]

Hmm. Ok, I'm glad I asked now. I reverse engrave and color fill acrylic mirrors a lot for license plates. I assumed it would be the same for these. Should I mask and color fill?

[Frank Corker]

Brian you are engraving from the front, not from the back, applying the finishing touches are pretty much preference. I used silver rub'n'buff, the gold looks good but not on people, white is very effective. Never tried masking it.

[James & Zelma Litzmann]

We don't have a lot of experience but the the first one we color filled with white, I think. Like Frank said its hard to get even, since then we have not done a color fill on them.

Good luck and let us know how it turns out.

God Bless,
Zelma (Psalms 18:2)

[Brian Robison]

Are ya'll using a wet newspaper on top to laser through?

[James & Zelma Litzmann]

I was going to send you a picture of one we just did, but I haven't got the knack of taking pictures of mirrors yet. But no we do not use anything, we just engrave on the front. We were a little skeptical at first, we were afraid of it bouncing off the mirror. It hasn't so far, now this is just with the black mirrors. We have never engraved on the front of a regular mirror. Good Luck.

God Bless,
James & Zelma (Psalm 18:2)

[Frank Corker]

I used the wet paper, but you have to be careful if your picture is large, the paper will dry off well before you finish and if that happens you get a stepped image. The next time I just went for it and it was better.

[Brian Robison]

Well, I finished up the art work so I'll probably be lasering it tonight or tomorrow night. I have one each, clear and black and I think I'll do the black one first. I'll try to take pictures (if I can remember).

[Stephen Beckham]

"Working with the glass without wet paper of some sort on the surface can cause stress cracks that may run like a pebble effects to a windshield..."

So - I've done with and without. Using a monicale I can see little tiny cracks when I don't use the wetting step. My buddy said I should put a piece of glass in a freezer after etching then put it in warm water - that would give me a quick answer.

I've never seen a "run" in one of the cracks - I have noticed more chips missing which caused bleed over between dots, but never runs.

Anyone have more conclusive data that proves or disproves the possibility of cracks forming and running?

BTW - I always use wet paper towel because of the above rumor or true statement which ever it is. It's a pain when doing 200 shot glasses - but worth it if someone could possibly freeze the shot glasses or freeze their beer mug and have it crack when liquid is added...

[Frank Corker]

Steve, it's funny that you suggested the wet paper towel, on one of the black mirrors, I used 'Bounty' because of it's superior water retention skills. It did remain wet throughout the engraving but I managed to get a pattern from the towel on the engraving! Now I use bog standard A4 copier paper soaked in washing up liquid and it gives a really good finish.

Regarding the cracks in the glass, I had a number of mirrors crack on me (not whilst I was looking at myself I hasten to add) but It was on the larger pieces where the laser was running too slow and the heat built up. As regards putting them in the freezer first, wow I'd say that was going to be dangerous, hot and cold differences would be too much I think

[Belinda Barfield]

Frank,

I used Bounty on a piece of stemware for a client "test". Same problem, Bounty pattern on the piece. Luckily I used my monogram on a piece of my stemware, so no real harm done, but lesson learned. Glad to know I'm not the only one with the Bounty experience, as at the time I just assumed it was "operator error". Tried the copier paper to see if there was any change and voila, no pattern.

[Stephen Beckham]

Sorry - that was a misplaces run-on sentence... In my question to find out if there would be long term damage, he suggested I take a test piece and run it normal process without wetting. Then stick it in the freezer to cool, hours later warm it quickly to force a heat stress test.

Although it might be a cool effect to freeze it and then laser it - that might cause a interesting crackled pattern. It would have to be on a thicker glass or tempered glass that wouldn't shatter.

Anyway - I've also noticed the pattern in the glass when using quilted picker-uper type papertowels. I now use a plain brown towel usually found in big rolls in the restroom. You know the stuff that doesn't work and you have to wipe your hands on your shirt anyway... well, I found a real use for it... I found it interesting above to use wet newspaper, I might try that and see how well it works compared to my papertowel.

Take care

[Belinda Barfield]

It would have to be on a thicker glass or tempered glass that wouldn't shatter.

Anyway - I've also noticed the pattern in the glass when using quilted picker-uper type papertowels. I now use a plain brown towel usually found in big rolls in the restroom. You know the stuff that doesn't work and you have to wipe your hands on your shirt anyway... well, I found a real use for it... I found it interesting above to use wet newspaper, I might try that and see how well it works compared to my papertowel.

Take care

Stephen,

It is my understanding that tempered glass cannot be lasered. Please let me know if you find that it can. I could do a lot of work with tempered glass, as well as polycarbonate if not for that pesky noxious gas issue!

Also, let me know about the newspaper. I thought about trying that as well but was concerned that the ink in the newsprint might bond with the glass. Haven't had time to test it yet. Post your results when you test, and I will do the same if you don't beat me to it.

[Stephen Beckham]

Hey do you think if the ink bonds to the glass I could charge some $5500 to tell them how I did it?

Sorry - bad post, but I couldn't resist.:rolleyes:

[Belinda Barfield]

Hey do you think if the ink bonds to the glass I could charge some $5500 to tell them how I did it?:rolleyes:

Shame, shame, shame!;) I'm just sorry I didn't think of it first!! Race ya' to the finish line!

[Mike Null]

Belinda

Contrary to popular opinion you can laser tempered glass with no problem. Like any glass if you over power it and use a slow speed you will make a hot spot causing rapid expansion thus cracking.

I gave up using wet paper and dishwasher detergent a long time ago as I didn't see any benefit to either. Instead I use a low resolution and do two passes. This produces a nice frosted effect without the micro-fracturing.

[Belinda Barfield]

Belinda

Contrary to popular opinion you can laser tempered glass with no problem. Like any glass if you over power it and use a slow speed you will make a hot spot causing rapid expansion thus cracking.

Thanks for the info Mike. Understanding that no two lasers are alike, could you give me ballpark settings for the tempered glass. I was told by someone who tempers glass that any application of focused heat would causing issues with the glass, i.e., it would no longer be classified as "safety glass". Since tempered glass is processed by compression the lasered area would be weakened and therefore susceptible to stress fracturing. Was I given incorrect info?

[Mike Null]

Belinda
My laser is 45w and rasters at 140 ips. I use 100p, 90s, 1000ppi and 300dpi; 2 passes.

As far as your information is concerned I am not qualified to provide the answer---but safety glass, which I believe is a 3 layer glass such as is used in automobiles, is routinely marked with a laser in applying colored marks of the Cermark type.

It is easy to break glass with the laser. People tend to think that more power and less speed, thus a more concentrated beam produce better, deeper marking. What really happens is that you get more micro-fracturing but not a better mark.

DPI can play a role in fracturing glass as well as a higher dpi focuses more heat on a spot than a lower dpi. (that is due to the overlap during rastering not that dpi increases anything else)

The bottom line is: for high quality work sand blasting is clearly superior to other methods of marking. The laser is just fast.

[Brian Robison]

I finished the plaque last night, but I don't have a photo ready yet to post. It looked OK to me but I should have run it with less dpi. There was an area of gray in the art work that don't contrast with the black well enough IMHO.
I'll get pictures up soon, if they came out OK. Darn thing was HARD to photograph!

[Brian Robison]

Crappy picture