White on black plastic

[Jim Reinhard]

I had a client bring me some parts.He had them laser marked by someone trying to sell him a laser.Unfortunatly for him they were all marked wrong.But some of these were black plastic and the mark is bright white.It is not deep so I dont think it was color filled.How could this have been done?

[Robert Silvers]

Fiber lasers tend to do that. Maybe YAG also, though I have not tried it.

[Larry Bratton]

I don't know about BRIGHT white, but cast black acrylic engraves white. In some cases it is bright enough as to not require filling.

[Jim Reinhard]

Fiber lasers tend to do that. Maybe YAG also, though I have not tried it.

Did a google search and I think you are right Robert.He had to have these done tonight so Im going mask and fill.Would be nice to have a speed 400 flex right now.

[Dan Hintz]

I had a client bring me some parts.He had them laser marked by someone trying to sell him a laser.Unfortunatly for him they were all marked wrong.But some of these were black plastic and the mark is bright white.It is not deep so I dont think it was color filled.How could this have been done?

Depending upon the plastic, a CO2 or a fiber/YAG will mark it, as mentioned earlier... they also make laserable plastics with microcaps (very shallow engraving), so that would be a white base with a black microcap. I'm going to guess that's not it, though, as you would likely notice the multiple plys.

During the NBM show, Trotec was using their Flexx machines to engrave black acrylic with their fiber and cut it out with their CO2. Is the engraving about coaster-sized, cut to the shape of the engraving?

[Jim Reinhard]

Depending upon the plastic, a CO2 or a fiber/YAG will mark it, as mentioned earlier... they also make laserable plastics with microcaps (very shallow engraving), so that would be a white base with a black microcap. I'm going to guess that's not it, though, as you would likely notice the multiple plys.

During the NBM show, Trotec was using their Flexx machines to engrave black acrylic with their fiber and cut it out with their CO2. Is the engraving about coaster-sized, cut to the shape of the engraving?

These were like the plastic pieces from a shop vac hose conector and attachments.

[Dan Hintz]

These were like the plastic pieces from a shop vac hose conector and attachments.

Probably a polymer... butyrate, etc. Can you get a close-in look at the engraving? Is it smooth, or is it slightly raised? If the latter, likely a fiber did it... foaming.

[Keith Outten]

White plastic can be spray painted with black paint. When you laser engrave the piece you get white text on a black background.

I do this all the time as I have to match colors for my window style ADA door signs. I use the same color engravers plastic that I cut letters and numbers from and paint the insert the same color as the sign blank. Its rare that I can find engravers plastic that matches both of the colors I need.
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[Jim Reinhard]

Probably a polymer... butyrate, etc. Can you get a close-in look at the engraving? Is it smooth, or is it slightly raised? If the latter, likely a fiber did it... foaming.
Yes ,it was slightly raised.I lasered ovals over them and then just masked and color filled .They came out nice.But I can now see a flex laser in my future.

[Bill Cunningham]

Black acrylic does engrave white, and it can be made whiter with a wipe of white acrylic paint..It also accepts photographs as good as granite, and using exactly the same settings. Sometimes I'll use a piece to test a granite engraving before I etch it in stone..
273709

[Vicki Rivrud]

Interesting, I've got some odd pieces of Black Acrylite and will have to try this out. Thanks for the info!

[Keith Outten]

Bill,

I assume that your black acrylic is cast and not extruded.
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[Jim Reinhard]

Bill,

I assume that your black acrylic is cast and not extruded.
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They are not acrylic .They are the black plastic hoses and conectors for shop vacs.They were labeld for storage.the engraving was white.So I am assumong as Dan said it was marked with a fiber laser.

[Bill Cunningham]

Bill,

I assume that your black acrylic is cast and not extruded.
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Actually I'm not sure Keith..This was a bunch given to my by my signmaker neighbor. He had broken a window on his truck cap, and bought it to cut out the piece he needed. I doubt if he would have bought cast for that job but stranger things have happened. This stuff has a brown paper backing on both sides and nothing is written on it.. I don't use a lot of acrylic so I'm not sure if there is a difference in the etched colour between cast and extruded of black acrylic

[Keith Outten]

Whatever it is the contrast is excellent for a solid color material without having to paint fill.

I purchase Acrylite from a local distributor and I always purchase cast because it engraves with lots of contrast. There is another reason as well, cast acrylic can be cut for routing templates because it holds up really well as a bearing surface. Extruded acrylic melts at a much lower temperature so routing templates don't last very long.

[Larry Bratton]

Most of the time, you will find cast acrylic with paper masking on it. Extruded many times will have a polyethylene film on it. As to whether your neighbor bought cast or not intentionally is a guess, but I personally purchase acrylic from Calsak plastics and their cast is cheaper than extruded. Reason being that they have a private label deal with a mfg. for their cast but have to purchase extruded outside of that arrangement. Cast will engrave a frosty white on any color where extruded will be a chalky white. To tell the difference, burn a piece , extruded burns silently and will drip molten balls , cast burns with a crackly/smokey flame and wont drip.

Actually I'm not sure Keith..This was a bunch given to my by my signmaker neighbor. He had broken a window on his truck cap, and bought it to cut out the piece he needed. I doubt if he would have bought cast for that job but stranger things have happened. This stuff has a brown paper backing on both sides and nothing is written on it.. I don't use a lot of acrylic so I'm not sure if there is a difference in the etched colour between cast and extruded of black acrylic

[Larry Bratton]

If this is not acrylic, are you sure it doesn't contain PVC? Best check on that , it could be hazardous to your health and your machine.

They are not acrylic .They are the black plastic hoses and conectors for shop vacs.They were labeld for storage.the engraving was white.So I am assumong as Dan said it was marked with a fiber laser.

[Bill Cunningham]

Whatever it is the contrast is excellent for a solid color material without having to paint fill.

I purchase Acrylite from a local distributor and I always purchase cast because it engraves with lots of contrast. There is another reason as well, cast acrylic can be cut for routing templates because it holds up really well as a bearing surface. Extruded acrylic melts at a much lower temperature so routing templates don't last very long.

Dug out the part sheet and it does have something written on it.. High impact plexiglass G.. The coasters in the picture I posted have had some white acrylic paint wiped across to brighten them up, but it also etches pretty white on it's own but the white acrylic craft paint makes it pop..

[Elliott Gerso]

This is a colored (black) acrylic that engraves white: https://www.inventables.com/technologies/black-on-bright-white-laserable-acrylic-sheet

[Dan Hintz]

This is a colored (black) acrylic that engraves white: https://www.inventables.com/technologies/black-on-bright-white-laserable-acrylic-sheet

That's the same stuff IPI, Marco, etc. sells, mentioned earlier... microcap plastics. It's a white acrylic with a black cap on it.

[Larry Bratton]

I reckon this could be a bit confusing. As Dan said, IPI and Rowmark make plastics with colored cores specifically for the engraving market. You engrave away the top layer to expose the underlying core. (the product type in Elliot's post). What I call standard acrylic and is marketed as Plexiglass, Pex as it's called in Europe, Acrylite etc. It comes in a variety of colors and transparency. It does not have a core and is the same color all the way through the piece. It is manufactured in two different ways, either extruded, made by pulling through a die or cast which is made in a mold. These acrylics are used for all kinds of things, displays, signs, etc. They are favorites of laser engravers because of their great ability to be cut with the laser beam and engraved. This is the type of acrylic that has been discussed in this thread and not the specialty engraving plastic with a core. Hope this serves to clarify.
Cheers