Corel Draw setting for glass?

[Keith Upton]

Several days ago I thought I read something about either a contour or inverting the image before laser engraving it on glass. But now I can't remember where I saw it or what it actually said. Am I way out in left field with this, or is there some trick evolving that stuff?

[Mark Sipes]

I don't recall the posting you are referring to Not sure why anyone would invert ( make a negative) of an image to print on glass. As for contouring.. that is shaping tool that may be used for just about any graphic but regarding glass specifically.. ????.

[David Somers]

Any possibility they were referring to etching on the back side of a piece of glass rather than the front side?

[Dan Hintz]

Ah, so reversing the image, not inverting it... that would make more sense.

[Dee Gallo]

Why wouldn't you invert the image? It seems to me anything black will engrave, giving you a frosted line or area. So you want to invert the image (make it negative) to get your white areas to look frosted and your black area to be clear (and appear darker). You would ALSO want to flip it if you are engraving the back of the glass.

So unless you WANT the black parts of the engraving to appear frosted, you would invert it.

That's my 2¢ FWIW

[Vic Velcro]

... unless you WANT the black parts of the engraving to appear frosted, you would invert it.

On occassion, I have rastered on glass opting for the blacks to be 'frosted'. I have done this when I used ink to fill the frosted areas with black or with color. When I did not intend to fill those areas with ink, I did invert the image before running the job. As Dee indicates, the effect has a better appearance (if not using ink to fill).

[Dan Hintz]

Part of the confusion is the OP has not mentioned (as far as I can tell) whatis being engraved. If it's text, then typically you do not invert B/W... if its an image, then inversion may be necessary to get a proper looking result. When I think of glass, my mind wanders to awards or simple text of one form or another.

[Keith Upton]

You are quite right Dan, I should have said for images or artwork. The actual artwork I had in mind were these:

http://www.wingsofwar.org/forums/attachment.php?attachmentid=88125&d=1367435056

http://www.wingsofwar.org/forums/attachment.php?attachmentid=87661&d=1366895719



If I want the black areas to appear darker, I should invert the images correct? If I do that, everything white here (these files have no actual background colors (they are transparent)) will be lasered and appear as frosted on the glass (front engraving in my case) correct?

Also, when I invert one of the images above in Corel, the black ares turn a light gray and nothing happens to the white areas... is that correct?

Thanks again for all the help.

[Mark Sipes]

Inverted like this?

[Mark Sipes]

The dog fight does not appear to be fair since the Brits are flying a jet...

[Keith Upton]

Inverted like this?

That's not how mine looks in Corel when I use the Invert effect. The white areas stay white and the black areas are turn a light grey.



The dog fight does not appear to be fair since the Brits are flying a jet...

Yeah, lol. That was actually a shot of the artwork with out the prop visible to show the details behind it a little better. The final version does have the prop ;)

[Dan Hintz]

That's not how mine looks in Corel when I use the Invert effect. The white areas stay white and the black areas are turn a light grey.

Change to a 1-bit colorspace before or/after you invert... if black is turning to gray, sounds like you didn't have black to begin with. Also, make sure you're running RGB, not CMYK.

[Keith Upton]

Thanks Dan, I'm new to CD... I'm an AI guy ;)

[Keith Upton]

You were correct Dan, even those that artwork was drawn in black in AI, Corel did not show it as true black. I corrected that and now when I invert it, the black artwork turns white and you can no longer see it on the screen. The clear areas did not change, which I expected since there is nothing there to invert. But that leads me to think that if I send this inverted image to the laser, nothing is going to "print".

So does this inverting trick only work on gray scale images like photographs and such?

[Dan Hintz]

You were correct Dan, even those that artwork was drawn in black in AI, Corel did not show it as true black. I corrected that and now when I invert it, the black artwork turns white and you can no longer see it on the screen. The clear areas did not change, which I expected since there is nothing there to invert. But that leads me to think that if I send this inverted image to the laser, nothing is going to "print".

So does this inverting trick only work on gray scale images like photographs and such?

It's a function of the substrate your engraving on, as well as the look you're after. For example, when engraving an award on glass, I want the text to be engraved... so it needs to be black in the image I send to the enngraver. Same with black marble. But we're used to seeing black text on a white background when it's viewed on the screen, so it can be passed directly to the engraver.

An image, however, is usually viewed with light areas viewed as light, dark viewed as dark, etc. If we sent that over to the engraver as is, the dark portions in the image would engrave as a light color (and vice versa). So for photos, it's typical to invert the colors. But what if we're engraving a light substrate, like a piece of white tile? In that case you would likely send the image over "as is" and color fill with black ink... black on the screen appears black on the engraving.

[Bill Stearns]

Hi All -
May I throw in my two-cents 'bout glass engraving.(laser engraving). If you use engraving software (mine is PhotoGrav 3.0 )- you specify the material you're engraving on - and the program does the inverting of image. Once imported in to Corel Draw (X5)- what is black will engrave ALSO: I've learned that if I dampen glass with a light coating of Dawn dish soap diluted in water the engraving turns out much nicer. (using Epilog 35 watt - )

Bill

[Bill Cunningham]

When working with photographs on glass or black granite (not line art or text) sending a positive image to the laser results in a negative image being etched, and this is not usually what you want. Sending a negative image to the laser etches a positive image on the glass or black granite.. Any text and line art would be left monochrome black.

[Dan Hintz]

I've learned that if I dampen glass with a light coating of Dawn dish soap diluted in water the engraving turns out much nicer. (using Epilog 35 watt - )

Plenty of us get great engravings without it... if you find you need crutches like soap, wet newspaper, etc. to get a good engraving, your settings aren't dialed in yet.

[Bill Stearns]

Dan - Was just trying to be of help, telling 'bout my experiencing better results using Dawn dish soap on glassware. (35 W Epilog - my settings 30 speed/100 power/400 dpi). Never could get the hang of using damp paper, etc. - I just dampen the glass with my fingertip. - 'least seems to work for me. Maybe you can help me with another issue: I engrave photos on absolute black granite tiles - have trouble getting some (most) images to engrave bright enough. Learned it helps some not to laser too deeply. (typical setting: 58 speed 37 power - 400 dpi). I do use Home Depot granite 'cause of price difference v.s other sources. - any ideas for achieving brighter engraving on granite? (I do brighten photos in Photoshop first - this helps, but I lose some photo detail- sometimes. Your ideas would be much appreciated ...

Bill

[Dan Hintz]

Dan - Was just trying to be of help, telling 'bout my experiencing better results using Dawn dish soap on glassware. (35 W Epilog - my settings 30 speed/100 power/400 dpi). Never could get the hang of using damp paper, etc. - I just dampen the glass with my fingertip. - 'least seems to work for me.
No problem, Bill, I'm just suggesting you can get rid of the extra step and mess if you spend a little time tweaking your settings. There are a few here who still hold to the idea that they can only achieve good images using soap, paper, et. al., but I always suggest to new folks they keep working at it until they don't need it.


Maybe you can help me with another issue: I engrave photos on absolute black granite tiles - have trouble getting some (most) images to engrave bright enough. Learned it helps some not to laser too deeply. (typical setting: 58 speed 37 power - 400 dpi). I do use Home Depot granite 'cause of price difference v.s other sources. - any ideas for achieving brighter engraving on granite? (I do brighten photos in Photoshop first - this helps, but I lose some photo detail- sometimes. Your ideas would be much appreciated ...

Engraving deeper (i.e., more power) will not net you brighter engravings. I would suggest running a power grid to determine the lightest power you can get away with while still providing a consistent engraving. Often you will see a brighter result with a second run over the same spot, but that's not guaranteed. Various coatings have been suggested over the years for a brighter etch, but I find them to be a red herring (at least in the sense of achieving a whiter white). Some will produce a perceived brighter etch by making the surrounding areas darker... in that case, I'd say it's an acceptable method, red herring aside.

Brightening in Photoshop will not net you brighter etches, but again, it can give the perception of such by providing a wider contrast over the image. For poor pictures, it makes sense to spend some time tweaking the contrast only within a specific area (judicious use of the lasso tool works well here). Sharpening certain areas can also be very useful. It's more of an art than a science, but you can be taught the basics without a problem.

One option for brightening is to rub white oil paint into the engraving. Rub it in, let it dry a bit, then buff off the excess. I've used that method before in a pinch, but it takes extra time I don't like to spend if I don't have to.

[Bill Stearns]

Dan - I appreciate your thoughts, your input. - gonna test engraving on granite using less dpi - been using 400. - wondering if wider spacing between dots will make a difference - and, still provide a satisfactory photo - guess we'll see. Thanks again.

Bill

[Mike Null]

Beauty is in the eye of the beholder. I know a number of experienced professional engravers who use the soap or wet paper methods. They know their equipment inside out so it seems to be a case of "whatever works".

I do not use those methods but when possible I use sandblasting on glass and crystal.

[Dan Hintz]

Dan - I appreciate your thoughts, your input. - gonna test engraving on granite using less dpi - been using 400. - wondering if wider spacing between dots will make a difference - and, still provide a satisfactory photo

Marble is a decent resolution substrate (some granites a bit less so)... I would expect 400dpi to work relatively well in most cases, but I wouldn't expect much higher to work. I wouldn't go below 300dpi, unless you are after that more rustic look.

[David Somers]

Here is a silly question asked out of complete ignorance.

It dawned on me in the last few posts in this thread that I always hear us talk about laser etching glass and some of the problems that can involve, and sandblasting glass which involves cutting your resist somehow and having sandblasting equipment available. But I never hear anyone refer to chemical etches? It has been a long while since I saw anyone do this, but it seemed to be a quick process, still involving a resist like sandblasting, and the paste that was used to do the etching was easily applied, rinsed off and neutralized and disposed of. (this was years ago of course. Regulations may have changed since)

Any know where this fits into the glass marking process nowadays?

Dave

[Mike Null]

Dave

I haven't tried it but I've heard that diy results are hit or miss. It still requires a resist so there is not a lot of time saved.

[Bill Cunningham]

If your using 400 dpi, make sure your photo is also 400 dpi.. Etching a 300 dpi image at 400 is going to be less than acceptable.
300 can be etched at 300, 600,or 1200 dpi. Titainium white oil paint applied to the granite will whiten things up. Granite will always etch grey, because it 'is' grey.. Marble (real marble) will etch white, and get whiter with a second pass..Real marble is almost goof proof, and can be etched directly from a greyscale image. Photograv, or any other conversion to 1 bit is not needed for marble (real marble, not the granite from lasersketch they called marble).