When creating a product or part using injection molding, it’s easy to get caught up in that piece’s actual production. Things like material, size, and complexity are all important factors to consider and have a huge impact on production. But what about the look and feel of your product? If your product or part is going to be seen by customers, it’s time to start thinking about plastic finishes.

Many different injection plastic parts of white, blue and black color spread on white background

What are the plastic finish types?

Plastic finishes are used by fabricators to give the product its final look, and to reduce the appearance of any blemishes or molding lines. These finishes are separated into grades classified by the Society of Plastics Industry, or SPI. The SPI states that plastic finishes are spread out across twelve separate grades, ranging from mirror shine to a dull matte. In general, these finishes can be placed in four broad groups.


Shiny plastic finishes

This group is made of finishes A-1, A-2, and A-3. All are incredibly smooth and shiny, but A-1 is unique in that it is a mirrored finish. These finishes are all obtained using diamond powder suspended in an oil solution. Such incredibly reflective surfaces are often used to make plastic mirrors or other optical parts.


Semi-gloss plastic finishes

Created using different types of grit paper, the semi-gloss finishes are smooth, but not to the degree of a shiny finish. Grades B-1, B-2, and B-3 range from medium to medium-low polish. These finishes can be used for the exterior of products as well as for parts that require a smoother finish.


Matte plastic finishes

Matte and dull finishes are used primarily for diecast and thermoset parts. They are created using a polish of fine stone powder. Matte finishes are categorized, predictably, from C-1 to C-3.


Dull plastic finishes

These surfaces are created using processes like sandblasting and can result in a finish ranging from satin to dull. These are the roughest and least polished grades and are often used for internal parts or for products that require such a finish.


Sandblasting a plastic car part. Plastic injection molding finishes are typically achieved through the molding process.

What plastic finish is best suited for you?

As with many choices made during the plastic injection molding process, the different elements used to create your product are best determined by the intended use of that product. That’s why it’s so important to have a trusted partner to work with; one that knows the industry inside and out. At Rex Plastics, we have decades of experience helping clients create exactly what they need. From massive production orders to unique prototypes, Rex Plastics is here to serve you for all your plastic needs. If you have a project you’d like to discuss, contact Rex Plastics with any questions or request a quote now.