I have a theory that McMaster-Carr actually sells every material you could ever want, but that it has these items so finely categorized that you just can’t find the bulk of the more unusual ones because you don’t know what to search for. Sort of like dark matter.
For example, you can search through their entire listing of “Plastics” and not find any two color sheets. If, on the other hand, you search for “Blank Engraving Plates,” you find a whole category of inexpensive two-tone plastic (ABS or Acrylic) sheets in a variety of sizes and color combinations, with or without adhesive backing:
They’re meant to be engraved with a hot iron that holds metal character stamps, but doesn’t that sound PERFECT for laser engraving? I got some of the 2"x4" black surface, white core ABS plates with adhesive backing (Item# 4071T161, ten pack for $8.07!) to cut/engrave durable and easily readable face-plates for some custom PC104 enclosures, which came out quite nicely given that I spent a total of 5 minutes playing with settings before cutting the lot of them:
The plates come with a protective plastic sheet over the colored surface. I found that if I removed it before cutting, the engraving came out very clean and white, but that hot gases from cutting marred the “micro-thin” black surface. I left the coating on when I cut my set, which kept the un-engraved surface nice, but resulted in some of the black coating getting melted down into the white engraved lines (plus it was a real pain to pick out the bits of coating from letters with closed loops).
I was in a hurry, and what I got is totally functional, but in hindsight, I bet I could have had it both ways if I removed the plastic coating and put something more easily vaporizable, like masking tape, over the sheets. I also could probably have tuned the laser settings a little more finely. Oh well, no regrets. The next time I want a fancy cover plate for a project I’m totally going to try out some of the other colors!
I never noticed McMaster carried this stuff; thanks for the tip!
If you ever need a large variety of colors and thicknesses, you can probably find them at johnsonplastics.com/. They can also arrange to make custom color combinations and can apply adhesive backing on most sheet products.
Note that some two-tone materials are not laser-safe or do not respond well to the laser. The Johnson Plastics online catalog shows small thunderbolt icons for products that are meant for laser cutting or engraving. We typically use either the IPI “Laserables” or Rowmark “LaserMax” brands, both carried at Johnson Plastics.
We stock 1/16" and 1/8" two-tone material with either a white core and black top layer (like the one in your picture), or with a brushed-aluminum top and black core (Johnson Plastics part numbers LZ901M2P08, LZ991G2P08, LM922354NMP, LM922402). They come in 1, 2, or 4-square foot sheets. For those brands, what has worked for us is to remove the plastic masking during engraving, dab the material with a damp paper towel and pat dry (don’t make sweeping motions to avoid getting dust and dirt into the engraved areas), then re-mask with a low-tack masking (such as part number SUS 016 at laserbits.com) during cutting. You can engrave with the low-tack masking on, but that sometimes leaves a gooey residue in the engraved areas.
Cleaning dirt out of the engraved areas is tough; certain cleaners that contain rubbing alcohol (like Windex) might rub off the top layer of color. One of our customers has found that dipping the pieces in gasoline cleans the parts well.
We use Diapthylate potting shells in some of our products.
Each of our sensors carries a unique ID internally, electronically, but we would like to etch that ID onto the sensor’s diapthylate potting shells. It etches well, a company called Tradewinds did it for us, but there is no contrast, and thus the ID is hard to read. Is there a way to etch this and still get any kind of decent contrast? I don’t think a two-tone plate like this will work for us because of the shape of our sensors.