Engraving Plastics: Part Three

By now, you know that acrylics are the plastic material of choice to fabricate in your laser. Material manufacturers have been producing laser-friendly acrylics for decades and offer a wide range of colors, thicknesses, and finishes for any type of craft or signage project.

However, not all acrylics are the same. The two main types of acrylics for laser engraving are extruded sheet acrylics and cast acrylics. This article will focus on what makes cast acrylic different from extruded materials and some of the unique ways you can fabricate cast acrylic in your laser.

Cast vs. extruded acrylic

Cast acrylic is made by pouring liquid acrylic into a mold or frame and allowing the material to set. This “casting” process differs from extruding acrylic and gives the finished product greater optical clarity than its extruded counterpart.

Due to the hardness of the material, cast acrylic is ideal for detailed laser engraving. The laser beam can easily penetrate the material without distortion, resulting in sharp, fine lines and intricate designs. When laser-engraving cast acrylic, there's minimal residue or discoloration left behind. This ensures that your engraved designs remain crisp and clean, requiring little to no post-processing.

The benefits of cast acrylic

Cast acrylic comes in a wide range of colors and thicknesses, enabling creative freedom. It's perfect for crafting signage, trophies, jewelry, and other intricate decorative items. Along with outstanding optical clarity, cast acrylic is very durable along with being UV-stable and outdoor weatherable.

Extruded acrylic tends to be slightly less expensive than cast acrylic, but that cost savings for the extruded version comes at the expense of the optical clarity and rigidity found in cast acrylic.

Lasering cast acrylic

Now that we’ve talked about the differences between cast and extruded acrylic and highlighted why cast acrylic is a great choice for laser engraving, let’s take a look at some of the unique applications and uses for cast acrylic.

Cast acrylic is available in several different forms. The three most popular for laser engraving are as follows: a single, clear sheet of plastic; a sheet of plastic with dye added to give a colored tint to the clear acrylic; and cast acrylic with a colored, laserable foil added to the BACK of the sheet.

Laser engraving the front or back of traditional cast acrylic can give you several different looks depending on the speed and power of your laser. You can either get a clean, almost transparent mark or a slightly frosted look. Either of these options can look great when creating signs with edge lighting or when you want to have a finished product that mimics the look of glass.

Cast acrylic products with a laserable foil on the back offers you a unique range of possible projects you can create. To engrave these types of cast acrylics, we’ll be using the “reverse engraving” process.

With traditional front engravable products, the colored cap (top layer) sits on top of a clear or colored core (base layer). When laser engraving through the top layer, you reveal the base layer, creating a contrasting mark. With reverse engravable products, the colored foil layer is on the back of the material with clear cast acrylic on top.

Reverse engraving is exactly what it sounds like. Instead of engraving on the front of the material, you’ll be lasering through the foil surface on the back. The lasered area will appear clear when viewed from the front. Reverse engraving through cast acrylic allows you to use several different secondary processes to create fully customized pieces with your laser.

One application is to reverse engrave a cast acrylic material with a laserable foil on the back and back light the finished product. Doing so will allow the light to shine through the clear, engraved area while the remaining foil blocks out the extra light. The result is a project that looks like the engraved area is lit while the rest of the piece is not. Because of the optical clarity of the cast acrylic and depending on how the piece is being back lit, it may be necessary to use a thin sheet of clear extruded acrylic as a diffuser panel between the light source and the piece.

Another application to use with a reverse laser engraved cast acrylic is back painting. The engraved area can be filled with any acrylic paint that can be purchased from a hobby or hardware store. This allows you to use a custom color to contrast the color of the foil to match whatever your design calls for. This process can be used to create signage that matches a particular Pantone color for a customer to maintain their branding and color themes.

One thing to keep in mind when reverse laser engraving is to “flip” or “mirror” your artwork so that appears correctly through the front of the material.

Conclusion

Laser engraving with cast acrylic is a game-changer in the world of creative expression. From outstanding clarity and precision to a versatile range of color options, cast acrylic delivers great results for any project. Its ability to maintain optical clarity during engraving, minimal residue, and resistance to heat makes it a top choice for intricate designs.

Whether you're crafting personalized jewelry, signage, or home décor projects, cast acrylic offers a world of possibilities. It's the material of choice for those who seek to bring their artistic visions to life with precision and elegance. Dive into the world of cast acrylic and elevate your laser engraving projects to new heights of creativity and craftsmanship.