The Importance of P-Graded Abrasives

Dennis Beardsley, Refinish Application Specialist, Norton | Saint-Gobain 
Mandar Joshi, Senior Product Manager of No-Fil Products, Norton | Saint-Gobain

When evaluating paper abrasives, one of the most critical considerations is the grading of the grain. This is especially important when you are trying to achieve the smoothest, most consistent finish. 

When it comes to grading systems, the gold standard for abrasive grains is set by the Federation of European Producers of Abrasives (FEPA). FEPA standards have a tighter grain size tolerance than other systems. In fact, FEPA requires 95% of abrasive particles fall within a specified range vs 60% in other systems. By minimizing the chance of larger outlier grain sizes, an abrasive that meets FEPA standards delivers the most consistent performance across different grit levels.

When a grain meets FEPA standards, it is designated as “P-graded.” You may see this indicated in one of a few ways. The two most common are:

• Grit Designation – For P-graded grains, the grit may be listed with a “P” in front (e.g. P100).
• Product Imprint – On the backside of P-graded abrasives, you will see the grit written with a “P” in front (e.g. P100).
   

Why should a P-grade matter to you?

There are many industries where the goal is to achieve a final surface finish with a uniform scratch pattern and consistent finish. The automotive manufacturing and aftermarket industry are examples. Nearly all major automotive paint manufacturers specify the use of P-graded abrasives, as stated in their technical data sheets. This is to ensure proper surface preparation before the primer or sealer is applied.

Figures 1 and 2 show the marked differences between using a P-grade abrasive and using a less-stringent standard. In Figure 1 where a non-P-grade abrasive was used, you can clearly see the scratch pattern, even at the finer grit levels.
 

In Figure 2 where a P-grade abrasive was used, you can see the much smoother, finer finish – even at the coarser grit levels.

If you were to paint over the surface in Figure 1, those imperfections would show through any color or clear-coat application. If the problem isn’t caught before painting, technicians may have to strip and re-do the process or risk delivering a product that the customer will ultimately reject.

Using a P-grade abrasive helps you avoid rework by creating the right surface finish long before any primer is applied. The smooth finish helps prevent bubbling and cracking by creating a consistent, unified surface.

See the multi-air cyclonic disc conversion process in action in the video below.
 

Finish Better with Norton

Unlike other abrasive manufacturers, Norton paper abrasives are nearly all P-graded. No other manufacturer offers such a broad portfolio to meet your finish application needs. If you’re interested in learning more, seeing a demonstration, or testing P-graded abrasives in your shop, contact us.