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View Full Version : Any way to fix uneven engraving in glass?



Scott Shepherd
09-13-2009, 10:16 PM
I've engraved some glass and it's splotchy and I can't seem to get rid of it. It's like the glass fractured at different rates and I can't correct it.

Any way to fix this, make it look all the same?

Darren Null
09-13-2009, 10:57 PM
Twonk about with the focus a little and re-re-re burn it until it cooperates. Might just be more/less dense patches in the glass. Or uneven surface. Anyway, multiply-engraved glass looks much the same as once-engraved glass. So just nuke the reluctant bits till they give in. That's what i do, anyway; although my unevenness problems are usually caused by glass curvature, but the principle is the same.

Scott Shepherd
09-14-2009, 8:06 AM
Thanks Darren, it was burned 3 times and then I bumped it from the fixture it was in, so I'm a bit afraid to try to burn it again once it moved, since it's small text on it.

Turns out it was where the top level of glass hadn't come loose yet. I can take a small pick and lightly scrape it and it seems to make it all look alike.

Dan Hintz
09-14-2009, 8:11 AM
Some of the less stubborn spots come out with a good Brill-O pad / steel wool scrubbing.

Clyde Baumwell
09-14-2009, 8:35 AM
I have used silver Rub&Buff to enhance the frosted/engraved appearance

Darren Null
09-14-2009, 8:52 AM
I bumped it from the fixture it was in, so I'm a bit afraid to try to burn it again once it moved, since it's small text on it.
Very wise. I have NEVER managed to match up a job perfectly once bumped. Particularly if a rotary is involved.

Glad it came out well.

Scott Shepherd
09-14-2009, 9:38 AM
Some of the less stubborn spots come out with a good Brill-O pad / steel wool scrubbing.

Tried a dishwashing scotchbrite pad and scratched the crap out of the glass, thus ruining it. Got any ideas on how to get the micro scratches out?

Luckily I had an extra blank, so I'm engraving another, but if this one dies for some reason, I'd like to be able to salvage it, since it has to be delivered today!

Martin Boekers
09-14-2009, 10:07 AM
Scott, there are different methods that sometimes seem to help.

It seems everyone has different experiences here.

I do find a general consensus is to apply liquid dishwashing soap to the surface of the glass as that does help, as does a second burn most of the time.

I usually burn at 1200 DPI if I have the extra time on it.

I also look at glass as being a lower resolution material and keep that in
mind when designing the project, such as using a block or more bolder
font as opposed to a more detailed finer lined font.

Even then sometimes the glass engraves, you can see it and feel it, but when you look at it straight on it appears to drop out or have a different density than the rest. Still looking to get a bit more consistant with it though.


Marty

Dan Hintz
09-14-2009, 10:42 AM
Tried a dishwashing scotchbrite pad and scratched the crap out of the glass, thus ruining it. Got any ideas on how to get the micro scratches out?

Luckily I had an extra blank, so I'm engraving another, but if this one dies for some reason, I'd like to be able to salvage it, since it has to be delivered today!
You scratched the glass with a Scotchbrite pad? Really?! You're supposed to rub, not try to start a fire :p The only way to get scratches out of glass (that I'm aware of, anyway) is to put even finer scratches in it using something like cerium powder.

I use some random pads Amy had sitting dormant under the sink for several years... steel wool with some red powder soap mixture caked on it. Don't recall the brand.

Scott Shepherd
09-14-2009, 10:58 AM
It's all done now but gluing the glass together and UV curing the adhesive. All the engraving (and re-engraving) is complete.

Martin, I took a video of something bizarre happening and those that engrave glass may have seen it. When I get some time I'll post the video online. It's something you have to see happen to believe. I've told people over the weekend what was happening and no one believed me. So I filmed it :) Now I have proof :)

I have a sample drying in the UV room now (That's a cardboard box that's sitting over 2 black light bulbs). If that glues up well (as it should, I tried it once yesterday and it worked fine), then we'll be happy.

Dan, I must be stronger than I thought I was :D

Bill Cunningham
09-15-2009, 8:34 PM
I had something happen to a set of wedding flutes this week that was really weird.. Chinese glass, it etched totally transparent !!! No frost at all.. I actually pulled them out of the cabinet, thinking heck!! These things are extruded acrylic, but nope. The only thing I can think of is they have a very high lead content, and/or some weird super hard glass. They certainly have a good sharp ring to them.. I etch literally thousands of glass items a year, and I have never seen this happen before..

Scott Shepherd
09-15-2009, 8:40 PM
Bill, what was happening to me was I was engraving lines of text and it would leave out a letter here and there. So you might have :

"ASSOCIATION" and it would engrave "AS O A ION".

When it got to the next line, you could keep watching it and BAM, the letters, one by one, would magically appear. One of the most puzzling things I've ever seen. I understand it all now, but to see it was a mystery for more hours than I wish.

Rodne Gold
09-15-2009, 10:13 PM
Do not use "Solid" engraving , convert the file to a raster file and instead of black , use a dark grey. What this does is break the graphic up to discrete "dots" and thus you get better control over fracturing.
Combine that with the The Wet newspaper and dishwashing liquid method.
Once you got "bad" engraving , nothing will really fix it barring trying to re engrave it..maybe...

Bill Cunningham
09-15-2009, 10:55 PM
I use 70-80% gray on most etching, including this one. This was just real weird glass.. If I ever see any more of these come in the shop, I'll just mask and sandblast them. It was just as if the laser was melting, and reforming the glass, thats why I did a double take and check to see if it wasn't acrylic.. Rub and buff fixed the contrast problem..

Brian Jacobs
09-16-2009, 12:34 AM
Bill, what was happening to me was I was engraving lines of text and it would leave out a letter here and there. So you might have :

"ASSOCIATION" and it would engrave "AS O A ION".

When it got to the next line, you could keep watching it and BAM, the letters, one by one, would magically appear. One of the most puzzling things I've ever seen. I understand it all now, but to see it was a mystery for more hours than I wish.

Scott,

You're not alone. The same exact thing happened to me last week and I thought I was seeing things. I purchased a case of 5x7 glass and was running a test sample at the time. I did increase power on consecutive runs, but that 'delay etch' effect never completely went away. This is scaring the heck out of me because I feel that I have to proof 'everything' before I move the piece off the table. Even harder if everything is inverted.

I've never seen this before and I don't understand why this is happening. If someone has an explanation, please let me know. I still have a case of this stuff (minus 1).

BTW- Maybe a good idea would be to make an initial pass at 70-80% black (and possibly 300 dpi) then follow up with a second pass at 100% black and higher resolution to capture the small details.

PS- I have been engraving dry. Maybe I'll have to go the soap and paper route.

-Brian

James Stokes
09-16-2009, 1:46 AM
I have had Corel files done in version 11. I am now using x4 and I have had lost letters more than once. I really think it is a Corel problem.

Scott Shepherd
09-16-2009, 8:22 AM
My lost letters weren't a corel problem, as the letters were being engraved and they did appear.

What I roughly figured out later is that I had the power too light. So what was happening was it was hitting the glass, but it wasn't enough to really fracture it like it needs to. But once it reaches a certain point or temperature from cooling down after the engraving, that thermal shock finally pushes the glass to fracture. I know that's not the technical side of it, but it's the only theory I could come up with.

I tried dishwashing liquid with no help at all. Then I cranked the power way up and it all worked like a dream. No dishwashing, no paper, no nothing.

Martin Boekers
09-16-2009, 11:18 AM
I've never really totally lost the letters. It just seemed that the letters didn't engrave (frost) evenly.

I wrote this off as the fratures maybe fractured a sliver as opposed to a dot pattern:confused:

Dish soap took care of most of the issues.

In the future I will try Rodne's idea of converting to raster image first.


Thanks,

Marty

Martin Boekers
09-16-2009, 12:41 PM
I had to open my mouth didn't I!:eek:

I have never had letters totaly drop out until 5min ago.

I was burning a pilsner beer glass and sure enough 3 letters were missing!
A second burn with a new glass, the same file still on the laser it turned out a perfect glass.

When will I learn not to challenge the "Laser Gods"!:o


Marty

Phil Garcia
09-16-2009, 4:28 PM
A few weeks ago, someone had posted that a setting around 150 to 200 dpi was better than using the higher settings due to the heat transfer causing the glass to cone so if the dots are further away from each other you do not get the flaking effect. I have tested this and with the better quality glass it does make a difference.