Recognising Hail Dent Damage

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Before you start, refer to the materials required and initial instructions.

Having observed countless dents over many years, it is natural for any PDR technician to readily recognise vehicles with hail damage just by passing near a car. Furthermore, it is a skill essential to the quotation process since the number of dents influence pricing. And of course the recognising of dents is a skill essential to the repair process since understanding the dent depth and size is one of the most crucial skills required when applying pressure to repair the dent.

Using the light, you can see that the dark line contrasted within the light bends caused by one or more dents. If you don’t yet have a light, you need to take the vehicle under cover to ensure you have sufficient lighting reflection without ambient light.
using the line technique to identify very minor dents

Generally, the PDR industry utilise special fluorescent lights to observe hail dents to accurately count dents and categorise into size and depth. Using the varying angles and light, technicians scan each panel, one at a time and carefully counts the number of dents. But technicians are quite experienced in doing this and have mastered the techniques of counting rather quickly.

It may seem simple enough to count the number of dents on panels. But with larger panels and in particular when there are a large number of dents, counting may not be as simple after all. It becomes easy to lose track of what dents were counted and what ones have not.

Counting the Dents

Once you have determined that a vehicle has hail dents, we need to get a sense of the number of dents on the vehicle. Obviously the most accurate method of determining the number of dents on a panel is actually counting them. It may be more beneficial to count smaller hail damaged panels first before graduating to large panels. As easy as it may seem it is a skill and eventually you require to count at a faster pace to provide quotations within 10 or 15 minutes.

Dent Density Technique

A more feasible method to count the number of dents or should we say get an accurate estimate is to count systematically in sections. First, count the number of dents in a specific known area. The dent count per unit area is known as dent density.

The large circle and the dents have been marked out to illustrate the number and type of dents within that large circle. This is an example of dent density. A larger dent also exists within that circle. More common than not, relatively few very large dents will be observed on vehicles.
mark out sizes

Once we know how many dents were in a specific area, you count how many of these unit areas make up the whole panel. A reasonable estimate of the number of dents can be achieved by multiplying the number of areas by the number of dents within that area.

Number of dents = Dent Density x number of unit areas

One method of estimating using this Dent Density technique is using masking tape or similar.

1. Mark out a grid area, lets say a 30cm x 30cm square grid using masking tape. Ensure that the measurement of the inner square is 30cm x 30cm.

2. Count the number of dents within the square. __________ dents per square grid

3. Estimate how many square grid areas make up the whole panel. __________ square grids in the whole panel

Number of dents = Dent Density x number of unit areas
= 6 dents per grid x 10 grid areas
= 60 dents


Another activity

For the purpose of training itself, you may wish to mark all dents on the vehicle panel being inspected using the special marking pens. You could try identifying and marking different sized dents as number 1, number 2, etc including annotating old damage as shown in the video.

Eventually, you will gain sufficient experience to perhaps mark only the smaller dents to recognise them and leave the larger easy to recognise dents unmarked.