Cermark & shades of gray

[R. A. Mitchell]

How much success have you guys had using cermark with a logo that has gradients?

My situation is that I have an advertising agency who wants a logo engraved on the back of an iPod Touch for one of their clients. The logo was color, primarily shades of light blue with multiple gradients, so I converted it to gray scale. I also ran it through Photograve on the Cherry setting. 75W laser, 600 DPI, 20 SP 100 P.

I didn't have the nerve to shoot the iPod right away, so I'm practicing on a scrap piece of chromed material. I don't like any of the results I have yielded so far. I started by trying the settings posted about iPod Touches on this forum a little while ago that used 1200/40/30, and it all washed off of my test piece. When I used my settings above, the cermark adhered OK, but it was so dark that all of the detail from the gradients was lost. More specifically, the lightest part of the gradients washed away, and the solid black areas remained. I'm reluctant to bounce down to 300 because the gradients look so grainy in Corel (after PhotoGrav) and I don't think the client will be pleased with the logo. For the record, I applied the cermark with an airbrush, and I thinned it in advance.

Off the top of my head, my problems could be (1) my test piece isn't chromed well, (2) I'm still putting the Cermark on too thick and (3) my power/speed settings are still off. I'm prepared to run more experiments because I'd like to land this client, but it will be futile if the truth is that you can't get smooth gradients using cermark. So back to my initial question - what is your experience with gradients and cermark on chrome/iPod Touches?

Thanks,

Rob

[Rodne Gold]

Dot Gain is too high with metal marking products to use em with mych success with shades of grey , you have to use gross halftoning to get acceptable results.
Better to run em thru photograv

[Stephen Kane]

I tend to change the lighter colours to deeper shades - works most of the time.

Stephen

[Frank Corker]

I think you'd have better chance of having a success story if you did it at 400. 600 will leave it dark, 1200 almost black.

My handbook says that for a 75 watt you should be doing stuff at the following:

300 dpi - nothing listed
400 dpi - 100sp/100pwr
600 dpi - 100sp/80pwr

Now I don't know about you, but I prefer to do my own tests and go from the recommended settings in my handbook rather than rely on what others do theirs at. Each laser varies a lot from machine to machine, some burn hotter than others. Go to a vehicle scrapyard, they've got tons of scrapped chrome plated stuff if you need to test, but before you go shooting into an expensive ipod, I think I'd prefer to do the research.

[R. A. Mitchell]

Frank,

I appreciate your advice. You have a lot more experience with cermark than me.

I went through a period of testing Cermark on chrome with other products a couple of months ago. At the time, my big concern was working with a dome-shaped chrome object. I was printing a bulls-eye pattern and text, so everything was either black or white, and that's where I wound up with the 600/20/100 setting.

This piece requires more subtlety. I still have my handbook, but I don't know how someone could get a good mark with 600/100/80 and have it stick. Perhaps this works with bare metal, but chrome is really giving me a work-out. I suppose I'll just keep testing to see what happens.

[Frank Corker]

Maybe it is a good point to tell you that if you apply too much heat, the metal might distort. I did some stainless steel business card holders, trying to get a good mark I reduced speed, came out great. Turned it over to see that I could see the shape of the logo I had engraved on the front on the back! The metal was no longer flat either.

[R. A. Mitchell]

You are correct again, sir.

I'm lucky enough to have a local Mac dealer who gave me the backs of a few salvaged iPod Classics. Using those pieces, I ran some more tests. I finally settled on 400/20/100 for this artwork and this medium. It's a bit dark for my tastes, but I showed the client a sample and she liked it.

Something that I would not have otherwise noticed if I had not been using scrap backs, however, is that lasering the image warped the iPod back. I lasered 4 tests on one back stepping down the speed by 20 each time. By the time I hit 400/40/100, the back no longer laid flat on the table. I shimmed it and ran the logo at 400/20/100, and when I was done, the back actually pops when you try to straigten it out. You can also see the shape of the image on the inside of the back.

Using a second scrap back, I hit it twice with the same logo. My test this time was the amount of cermark I applied to the back. On the first hit, I basically frosted the iPod with Cermark. When I engraved it, the image was very faint, and there wasn't any warpage in the back. When I did the second image, I applied Cermark until it was opaque and an even shade of tan. This image was the one the client liked, and the blacks were clear and dark. It also put a warp into the back, although not as severe as the back that I hit five times, and you could see the outline of the image from the inside of the back.

I doubt I ever would have seen this effect had I not engraved scrap iPod backs. There are fourteen clips that hold the back very securely to the iPod. I doubt seriously that the image I lasered on to an iPod will put enough stress on those fasteners to cause them to fail, so I don't see how I would be able to notice the warpage if it was connected to the iPod. Therefore, I feel pretty safe lasering this image to a new iPod.

However, I'd be reluctant to do an image that covered much more than 25% of the back of the iPod. The back that I hit 5 times is really out of whack. I doubt it would case the fasteners to fail immediately, but I think it would put a lot of stress on the iPod's frame over time. Of course, I'm not an engineer - just a guy who doesn't want to wreck a bunch of $300 electronic devices for my customers.

I offer this FWIW,

Rob

[Brian Robison]

Just make sure to document your setting someplace.
I hate it when I forget to do that!!!

[Bill Cunningham]

I've done a photograph on stainless with cermark, and 'no' photograv.. Just used the clipart setting in the epilog driver and 600 dpi.. can't remember the speed, but was probably about 20/100.. Came out fine! It's posted on the creek somewhere..