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The Definitive Guide to Grain Patterns in Metals Polishing


As part of our mission “to provide the highest quality metal finishing services for both the architectural and commercial markets,” Diamond Brite Metals has begun to clarify the ambiguities that plague the metals polishing and finishing markets. Our goal is to create a common language, used by each step of the metals supply chain, to avoid miscommunication and unnecessary delays and costs for the ultimate end-user. Finishes and the language used to describe them vary across geographical regions and localized polishers. Diamond Brite Metals has synthesized the different polishing dialects into a common language easily used by distributors, processors, and end-users.


Previously, we have outlined and defined the vast amount of architectural and commercial metals finishes available to end-users. Industry finishes such as #4 or #6 are facially vague. In another post, we explored the different #4 finishes available: commercial #4, true #4, and sanitary #4. This post will focus on the different grain patterns, which contrary to popular belief, are a different specification than the ultimate requested finish.


Difference between Finish and Grain Pattern

The finish is the ultimate surface result or texture whereas the grit pattern is the finish’s direction relative to the product. When submitting an RFQ for metals polishing, it is important to remember to specify not only the finish but also the grit pattern.



Short-Grain

The short grain pattern is the most common finish and it is produced on a variety of both flat rolled and long product. The pattern consists of short, interrupted lines that are the result of the abrasive belt’s intermittent contact with the product’s surface. This grain pattern can produced with a #4, #6, #7, grit, or RA finishes. This grain pattern is also known as a brush or satin finish.





Long-Grain

The long-grain pattern is a special pattern that is usually requested when aesthetics are important. The pattern consists of long, continuous lines that run the entire length of the product without interruption. The result is from the scratching of the locked abrasive wheel upon the surface. This grain pattern can produced with a #4, #6, #7, grit, or RA finishes. This grain pattern is also known as a hairline finish.


Circumferential Grain

This grain pattern is the common grain imparted on cylindrical shapes such as pipe, round tube, and round bar. This grain pattern can produced with a #4, #6, #7, grit, or RA finishes.





Mirror #8

The mirror #8 grain pattern is synonymous with the mirror #8 finish. There are no grit lines. The #8 Mirror can be produced on all products. The grit lines are completely removed by successively fine polishing with abrasive belts and buffing with compound.





Non-Directional

The non-directional grain pattern is a non-linear grain with no uniform pattern. The grain is achieved through successively finer linear polishing and then polishing with an orbital polishing unit. This is also known as angel hair or vibration grit patterns.


It is important to understand the difference between finish and grain pattern because they both affect a product’s ultimate surface quality. Here at Diamond Brite Metals, we are the authoritative resource on metals finishing and polishing. To submit an RFQ for metals polishing, please contact Sales@diamondbritemetals.com.


Cheers,

Colton

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333 Cedar Avenue
Middlesex, NJ 08846

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