preparing a photo fro engraving on anodized aluminum or coated metal

[David Rust]

Hi all,

I am going to experiment today and try to nail down a process for preparing photos for engraving on anodized aluminum.
I do a fair amount of photo engraving on wood, however I want to do more on another substrate.

How do you process you photos for engraving on anodized aluminum or other coated metal?

What I am going to try:
1. Convert to 8-bit gray scale
2. Adjust Tones
3. Run some tests

I plan to get a roll of colored aluminum flashing from Home Depot for practice.

Thanks,
Dave

[Dan Hintz]

I prefer to see the 1-bit version before engraving... that tells you right away if something has the correct shade compared to the rest of the item. Sometimes looking at a grayscale doesn't give you what you need.

[David Rust]

I did a comparison between running an 8-bit gray scale with tone adjustments and the same picture processed with PLP.

The Gray scale pic had "hash marks" or a matrix of "dots" throughout the engraving, not very eye appealing... Any ideas how to get rid of these?

I had a lot better results with the PLP processed photo...... hmmm.... I still would like to figure out how to process the photo without the use of PLP and get decent results...

[Dan Hintz]

Search for the Gold Method here... that will give you the overall process. You need to select the proper halftone pattern for the material you're working with, and everyone has their own favorites.

[Scott Shepherd]

Any reason you aren't just using ordered dithering in your driver? People say that works well on the Epilog. No need to process much of anything.

[David Rust]

Any reason you aren't just using ordered dithering in your driver? People say that works well on the Epilog. No need to process much of anything.


I guess the real question is: Does a dithered Gray scale yield a better picture than a conversion to Monochrome using PLP? I think it may depend on the substrate. I have found that a substrate like anodized aluminum tends to either have the color of the anodizing or the color of the aluminum, no in-between, so a Monochrome engraving may be better here. The Home Depot coated aluminum flashing acts like a paint, I can burn partially through the color layer with the middle gray-scale and not reveal the aluminum, so the dithered gray scale may be the approach here...

I ran samples of both and the Monochrome results seem to be more appealing to me, but that may be because of the Home Depot substrate not having a nice transition from the color coating to the aluminum underneath...

[Dee Gallo]

David,

I did some comparative tests a long time ago. I like to use the same photo for all tests to eliminate comparing apples to oranges. Here is a pic including a piece of scrap brown coil stock (and bent at that, LOL). I used PhotoGrav for this one, because the stronger contrast and more simplified dot pattern seems to look best in my eyes. Coil stock engraves the same as anodized aluminum.

You can see the difference between PhotoGrav on the coil stock far right as opposed to the laser tile on the bottom left which is greyscale. The detail and contrast are complete opposites.

cheers, dee