In this article we will discuss Feather Edge, Prime and Block Sand (FPB) in detail. What specifically is the operation, what do the major database providers say about it and how is it properly calculated in the estimate.

What is involved in preparing a repaired panel for refinishing, whether it is a bodywork area or a sectioned and welded area?  The answer is commonly referred to as the Feather, Prime and Block Process.  This article will assist in dispelling the myths, explaining the truths and outlining the required but not-included procedures to restore a repaired or replaced panel to the condition of a new, undamaged panel.

How Do “They” (Audatex, Mitchell, and Motor/CCC Pathways) define this operation or simply what do they say about it?

The Audatex Procedural Pages (P-Pages) (Database Reference Manual: Section 4-4 Refinish Guidelines, Page 142) states:

Feather / Prime / Block:

“Audatex recognizes that Feather/Prime/Block are required operations when replacing welded-on panels.  Time to perform this operation is included in the Audatex time for welded panel replacement in the seamed areas, to bring the panels to the condition of a new, undamaged panel for the purpose of refinish.  Although the time is included, Audatex does not provide a material allowance for the Feather/Prime/Block process. If necessary, the determination and assessment for materials is best provided by the estimate preparer for consideration and allowance during the estimate preparation process.”

Feather, Prime & Block are required operations in the panel repair process, however, Audatex Estimating does not provide a labor time allowance for repaired panels since the amount of time is subjective.

Audatex Estimating

• Is able to allocate a portion of the repair judgment time to FPB for any part with a refinish record attached.
• Displays FPB under refinish labor.
• Calculates FPB materials.
• Identifies FPB labor and materials on the estimate.

When the FPB feature is enabled, and both Repair and Refinish operations are selected on the Part Edit window, the repair operation expands to show the breakout of how much of the repair operation is allocated to the repair time, and how much is being allocated to FPB (Refinish).

Allocating Feather, Prime & Block on the Damage Page:

1. Verify that the Rates page has a labor rate for the FPB Materials Rate.
2. Click Damage on the left side navigation.
3. Click a part to open the Part Edit window.
4. Select the Repair and Refinish operations and provide a repair time.
5. The repair operation expands to show the breakout of repair time and FPB time.
6. Provide how much of the repair time needs to be allocated to FPB
   1. When FPB time is allocated, it will be automatically deducted from the Repair
   2. The FPB time cannot exceed the total Repair time provided in Step 4.
   3. See Additional Information for other calculation factors / limitations.

When FPB is allocated for a repair operation, the time is added to the Estimate Report in the refinish breakout under the refinish operation for the same part.

The Mitchell Procedural Pages (P-Pages) (Procedure Explanation: P16, Procedure 28 – Refinish Procedure) states:

Feather, Prime & Block

“Is the Not-Included refinish operation that completes bodywork repair from 150 grit smoothness to the condition of a new undamaged panel, and the point at which refinish labor time begins.  The labor and materials associated with feather, prime and block may vary depending upon the size of the repair area and should be evaluated when determining the work to be performed.

See Welded Panel under Estimating Information (General Estimating Information >>>Labor General Information).”

Welded Panels

“Replacement labor times for new panels that are joined by welding include the necessary use of inserts and accepted sectioning guidelines developed by OEMs, I-CAR, and TECH-COR.  The labor times for welded panels include grinding, filling and final sanding with up to 150 grit sandpaper to match the original panel contour.  Labor times do Not-include the Feather, Prime and Block refinish operation.

See Procedure 28 in Procedure Explanation section, for information on Feather, Prime and Block.”

The MOTOR Information Systems CED P-Pages (Guide to Estimating: Refinish Time Premise) state:

PRIME & BLOCK

“Prime & block (high build / primer-filler) is a required procedure that restores a repaired panel surface, including the joined areas of replaced welded panels, from 150-grit finish to that of a NEW UNDAMAGED condition.  It is MOTOR’s position that prime & block is a refinishing process best reserved for the judgment of an estimator / appraiser following a thorough on-the-spot evaluation of the specific vehicle and damage in question.”

As you can see, all three database systems basically state the same opinion: A panel MUST be restored to that of a NEW, UNDAMAGED PANEL.  A NEW, UNDAMAGED PANEL is defined as a component manufactured to the same exact standards as the components installed on new vehicles with a smooth painted surface (e-coat/electrodeposition primer) and a replacement part from the vehicle manufacturer without exterior trim, interior trim or attached components.  Let’s now look at what exactly is meant by Feather, Prime and Block

Feather (Feather Edge):

“is defined as the process of using a pneumatic orbital Dual Action (DA) sander or a sanding block with 180-grit followed by 220-grit and 320-grit sandpaper to level out the surface topcoats and imperfections, in preparation for primer coats.”

Prime (Priming/Primer):

“is defined as the process of the application(s) of etch/acid/wash primer (if required by your paint manufacturer) and epoxy primer (depending on the paint manufacturer’s recommendations as well as the OEM requirement, this application is generally required prior to the application of body filler), primer filler/surface primer and guide coat (if applicable).”

Block (Blocking aka Sanding):

“is defined as the process of using a pneumatic orbital dual action (DA) sander, a sanding block and/or sanding pad to level out the primed surface to be at or near level with the adjacent painted area to give a smooth visual transition between the original undamaged area and the repaired area(s).”

Now that we have defined the Feather, Prime and Block process, let’s look at the process to perform this procedure.  After the body filler and surrounding area is leveled with 150-grit sandpaper, the following not-included procedures are required:

1. In general, sand the surrounding area with a sanding block or DA sander with 180-grit, followed by 220-grit and 320-grit sandpaper. A tip is to sand and prep the rest of the panel for refinishing topcoats to prevent priming “ghost lines” or shadowing of the primed area.  Scuff the surrounding area of the panel with a red scuff pad, water and blend prep paste, in preparation for topcoats later in the refinishing process.
2. Blow off and/or vacuum all dust residue off the vehicle.
3. Mask off body filler repair area to avoid wetting or soaking the body filler, with wax and grease remover. Wax and grease remover will soak through the filler and get trapped, causing solvent issues during curing.  Ensure to clean the painted surrounding panel area thoroughly.
4. Wipe the panel with a damp towel and blow dry with clean compressed air. Remove the masking tape over the body filler area.
5. Place the vehicle in the spray booth.
6. Wipe down all edges with wax and grease remover and ensure you dry the area. Use caution to avoid wetting the body filler.
7. Mask all edges and adjacent panels for overspray. Back mask the perimeter and create a soft, rolled edge with masking paper, do not create any hard lines. Allow adequate spacing for the primer overspray to land without contacting the edge of the masking paper and tape. Primer near the edge of masking paper and tape may create an edge that will be visible after the repair is completed, even if the amount of contact is light.
8. Cover the vehicle for priming.
9. Blow off the vehicle with clean compressed air and wipe the vehicle with a tack rag. Place a lint free rag on the panel and feel the body filler to ensure the proper contours and straightness has been achieved.  At this time, carefully look for any pinholes.
10. Mix the acid/etch/washer primer and/or epoxy primer (specific to your paint manufacturer’s directions).
11. Mix the surface primer/filler and apply the required coats as per your paint manufacturer’s directions. If priming flexible parts, utilize adhesion promoters and flex additives as required. After the first coat, visually re-check the panel for proper contours and straightness. Use reverse priming (applying primer from the outside-in) to prevent trapping dry overspray, leading to layering within the primer material.
12. Bake the primer at the proper temperature for the proper amount of time (bake cycle) as per your paint manufacturer’s recommendations.
13. After, a proper cool down, check the primed areas for proper coverage using guide coat and then remove the vehicle from the booth.
14. Place the vehicle into a repair bay or prep area for Block Sanding. If possible, leave the masking paper and masking tape in place to keep the sanding sludge from entering the recessed areas and crevices.
15. Fill a spray bottle with water or use a hose to wet the panel and lubricate the sandpaper and wash away the sludge. If using a bucket, be sure to use a grated shelf to prevent sandpaper and tools from coming in contact with the debris that will accumulate in the bucket.  Or dry sand the panel depending on the process in your facility and based on your paint manufacturer.
16. Now, you are ready for the Block Sanding process. Prepare your sandpaper (220 wet/dry and 320 wet/dry sandpaper) for your sanding block and/or sanding pad.  Remember that refinish time starts at 400 wet sandpaper.

Now to the big question, how do you calculate the FPB process?  As you have read above, all three database companies basically state that for the Feather, Prime, and Block process, determination, and assessment is best provided by the estimate preparer for consideration of required labor time and allowance of materials during the estimate preparation process.  Larry Montanez of P & L Consultants LLC, and Mike Anderson of www.CollisionAdvice.com, have been conducting time test studies to determine a fair and reasonable calculation of the Feather, Prime and Block (FPB) process.  And to be honest, not much has changed in the past 15 years since the articles on this topic by both were published.

Method 1

The 40/20 – A damage assessor calculates 40% of the total repair time for the feather edging and blocking process, under body repair labor, plus materials and then 20% of the feather and block time under refinish time which plus materials for the application of primers.

For example, let’s use a 2025 LM X65s SUV (a fictious sports utility vehicle with four doors, a tailgate and a quarter glass with a visible C-Pillar and D-Pillar).  The left rear quarter panel was replaced using a sectioning procedure though the C-Pillar, D-Pillar and the rear area of the rocker panel.  Let’s say that after the technician has completed the welding and dressing procedures of the sectioning areas and the mating flanges, we will now have to calculate the amount of repair time for those areas.  The following is an example for an explanation of how to calculate the FPB for this vehicle.  Remember that the repair for the welded areas is included in the replacement time of the panel to 150-grit, but shop materials (body filler, sandpaper, etc.) are not included.  The following repair times are only examples so you can visualize what you would do. They are included in the replacement time of the panel up to 150-grit, but shop materials are not.

If we take the 2.4 hours of Feather and Blocking and now want to calculate the time to apply primers, we will now take the 2.4 x 20% = 0.48 hours rounded up to 0.5 hours Refinish time. Using a labor rate of $50 hr for all operations, a paint materials rate of $30 hr, and shop materials rate of $7 hr we can calculate the following:

This would account for an additional $145.00 in labor and an additional $31.80 in materials, based on the rates we used.

Method 2

Let’s look at the same exact numbers using Method 2 which would be taking the total labor repair hours of 6.0 and multiplying it by 30% and placing the sum under refinish time.  Many find this Method easier to calculate, explain and get reimbursement.

Now keep in mind that the mating flanges, to the replacement quarter panel mating flanges, would need sanding, priming and scuffing prior to refinishing.  No blocking would be necessary, and as such, this is where you would need to use experience and reasonable calculations to determine the time allotment for this operation.  So, in this example, the quarter panel is joined to the following components (number of welds), followed by the suggested repair time and the primer refinish time (no clear coat allocation).  Keep in mind that you will have inner mating and outer mating flanges to prepare, however only outer panels would require scuffing.  Keep in mind that repairing these panels would then require refinishing applications and some of the components may have no listed refinish time and you would have to determine and allocated time.  Please remember to add clear coat to all the refinish times.

• Rocker Panel Reinforcement (9) 0.3hrs / 0.1hrs
• Inner Rocker Panel (8) 0.3hrs / 0.1hrs
• Outer Wheelhouse (13) 0.4hrs / 0.1hrs
• Front Extension (3) 0.1hrs / Incl
• Inner Quarter Panel/C-Pillar (24) 0.6hrs / 0.1hrs
• Inner Quarter Panel Reinforcement/Glass Opening (7) 0.3hrs / 0.1hrs
• Inner Quarter Reinforcement Front/C-Pillar & Glass Opening (31) 0.6hrs / 0.1hrs
• Reinforcement Plate Outer (2) 0.1hrs / Incl
• Gutter Panel (6) 0.2hrs / 0.1hrs
• Tail Lamp Panel/Rear Body Panel (12) 0.2hrs / 0.1hrs
• Rear Floor Side Extension (19) 0.2hrs / 0.1hrs

This would total 3.3 hrs of body labor and 1.0 hrs of refinish labor for priming.

Method 1 Combined Totals:

Labor Combined 3.3 + 1.0 + 2.4 +0.5 = 7.2hrs x $50.00 = $360.00

Shop Materials $39.90            Refinish Materials $45.00

Method 2 Combined Totals:

Labor Combined 3.3 + 1.0 + 1.8 = 6.1hrs x $50.00 = $305.00

Shop Materials $16.80            Refinish Materials $77.10

Now some other operations to consider that would be associated with Body Labor, Refinish Labor, and material costs would be:

• Blow off vehicle 0.1hr Body
• Mask off body filler area $5.00 and 0.2hr Body
• Scuff surrounding area of the panel 0.5hr Body
• Towel off vehicle and dry 0.2hr Body
• Place vehicle in spray booth 0.1hr Body
• Mask for Primer $10.00 and 0.6hr Body
• Car Cover for Primer $10.00 and 0.2hr Body
• Mix and prepare corrosion resistant primers (epoxy) 0.3hr Refinish
• Blow off vehicle and tack $2.00 and 0.1hr Body
• Bake cycle fuel charge for primer applications $10.00
• Set Up Stands for Components in Booth $2.00 and 1.0hrs Body

Please keep in mind that these numbers are just for examples to have you visualize the operations and costs of those operations.  We cover these types of calculations and decisions each month in our Collision Hub C20 Estimating Group.  Please feel free to email us with any questions you might have.