Cosmetic Criteria

Microform Precision divides our cosmetic requirements into four categories: A, B, C and D. A is the highest and consequently requires the most effort to attain. Likewise D is the lowest and will be the fastest and cheapest option. For most applications, either B or C would be advisable. Choosing the most appropriate cosmetic class for your application will help to ensure a finish that will be pleasing to your end user without increasing the time and cost beyond what is needed. Following are a series of the most relevant excerpts from Microform Precision’s cosmetic inspection criteria.

Surface Classification

Class A: Class A finish is the highest quality finish Microform can provide. It is often specified for high visibility surfaces such as control panels, front covers, etc. in which the Customer demands the highest quality appearance. This Class is for surfaces that are of such prominence that imperfections will tend to degrade the public image of the product.


Class B: Class B finish is a quality finish with only minimal imperfections. A Class B finish is the most common finish for exterior surfaces. It is normally specified on surfaces such as external covers, panels, and parts that are fairly prominent.


Class C: Class C finish allows more imperfections than Class A or B. Class C is often specified for interior surfaces not readily visible, surfaces that will be covered by another part when assembled, or surfaces which the Customer feels do not need to meet a high cosmetic finish. This Class is generally used for parts or surfaces which are not viewed after installation or viewed only for service.


Class D: Class D finish might be used when cosmetic appearance is not important. With a Class D finish, all imperfections are permissible provided they do not impair the function, safety, structural strength, environmental, electrical or dimensional requirements of the part; part is usually never viewed.

Viewing Time and Distance

Class Distance Time
Class A 12 inches 6 sec/ 12″x12″
Class B 16 inches 4 sec/ 12″x12″
Class C 16 inches 3 sec/ 12″x12″
Class D 24 inches 2 sec/ 12″x12″

Acceptable Imperfections

Imperfection Class A Class B Class C Class D
Abrasion None None Light **
Bleeding* Minimal Light Light **
Blister* 3 x .010 5 x .010 5 x .020 **
Burr None None 10% of mat. Thickness **
Chip* None None 1 x .030 **
Color Variance* Minimal Light Moderate **
Corrosion None None None **
Crack None None None **
Crater 3 x .010 5 x .010 5 x .020 **
Dent None None 1 x .030 **
Ding 3 x .010 5 x .010 5 x .020 **
Die Mark None Light Acceptable **
Dirt None None Moderate **
Discoloration* Minimal Light Moderate **
Fracture None None None **
Grainy Coating/Orange Peel* Minimal Light Moderate **
Gouge None None 1 x .030 **
Mar 3 x .010 5 x .010 5 x .020 **
Pinhole 3 x .010 5 x .010 5 x .020 **
Pit 3 x .010 5 x .010 5 x .020 **
Run* Minimal Light Light **
Rust None None None **
Scratch 3 x .010x.125 3 x .010x.25 Moderate **
Smudge None None Moderate **
Specks 3 x .010 5 x .010 Moderate **
Stain* None Minimal Light **
Streaking* None Minimal Light **
Forming Stress Marks Minimal Light Moderate **
Tooling Marks None Light Acceptable **