Engraving on Black acrylic

[Carol Barbero]

Okay, I'm ready to do a graduation announcement for my nephew on black acrylic. It has the school logo, a photo of him, and text. Do I need to invert anything or should it be "normal" engraving. Also, the picture is a color pic, would I be better off changing to gray scale. I'm such a novice!

Thanks in advance
Carol

[John W. Love]

Carol,
I haven't done any engraving on Black Acrylic, but you will need to convert it to grayscale. Are you using photograv or are you manipulating the picture yourself? I am assuming you are engraving on the front since it is black Acryllic. Is that correct? If you are manipulating the photo yourself you may want to look through some of the threads on here on engraving on marble or granite because there is some excellent advice on how to get your photo just right by lightening and darkening different areas.

[Rodne Gold]

You have to invert when engraving on black , the laser engraves all the "black" in the picture.

[Chris J Drew]

Hey Carol.

You can get more control over the result by converting to 1-bit in Corel-Draw, rather than relying on the Epilog driver to interpret your greyscale.

In Corel, select your image & choose "Bitmaps/Mode/Black & White (1-bit)..."
Select the "Stucki" dithering pattern & adjust the slider to tweak the result, you can pan around your image & check the preview.
Pay attention to where you have black-to-white gradiends or detail in your image, you always have to "juggle" how much to lose during the conversion.

This method is much better than converting to a greyscale & then having the driver do the dithering ( even though the "Stucki" dithering in the Epilog Driver is very good, for photos you need more control over how the dithering is applied to light & dark, gradients & details etc )

You can get better results by experimenting with adjustment of brightness & contrast of the image before doing the conversion.

Good luck!

Chris.

[Frank Corker]

Yes it needs to be inverted. If you decide that you want to remove the background before inverting it, then it has to be black because when you invert it, the black will turn to white and won't engrave.

[Carol Barbero]

Thank you all for the advice. I'll give it a try tonight!

[Brian Robison]

And make sure to use cast acrylic.

[Steve Clarkson]

Not sure......but I think all colored acrylic is extruded......no one that I bought acrylic from has ever confirmed it......they just say they don't know.

But the only time it really makes a difference is on clear acrylic.

[Brian Robison]

I've buy extruded acrylic in black.
I use it all the time as a back piece for my license plates.

[Rodne Gold]

Burn a piece , cast burns with a crackle and wont drip molten flaming balls , extruded will burn silently and drip molten flaming balls

[Brian Robison]

Ouch! That's gotta hurt.

[Mike Null]

Steve

Check out Rowmark colorcast acrylics in the Johnson Plastics catalog.

[Larry Bratton]

Not sure......but I think all colored acrylic is extruded......no one that I bought acrylic from has ever confirmed it......they just say they don't know.

But the only time it really makes a difference is on clear acrylic.

I buy cast colored acrylic from Piedmont Plastics regularly. Just because it is colored doesn't mean it's extruded.

[Frank Corker]

I have about 2 tons of different coloured acrylic. All of it is cast. I actually don't have any of it which is extruded.

[Rodne Gold]

Degussa who supplys Euro and africa make a huge range of extruded colours and others
Extruded will stress crack with solvents far more than cast
Extruded is generally far tighter in thickness tolerance than cast - cast can vary by more than both plus and minus 10-20% over a sheet.