What are high spots, low spots and tool marks in PDR?

Written by the DentPicks Editorial Team · Technically reviewed by Vytas Kucinskas, Founder & Master PDR Technician

Published: Aug 19, 2026 · Last reviewed: Aug 19, 2026 · 9 min read

Three phrases come up constantly in paintless dent repair, usually at the exact moment a customer is trying to understand why a repair took longer than expected or why a shop is being cautious about a panel: high spots, low spots and tool marks. They are the vocabulary of the finishing stage — the last ten percent of the work, which routinely takes half the time.

Knowing what they are tells you what a technician is actually doing when a dent that looks "basically gone" still has them working on it, and it gives you a precise way to describe anything you are not happy with.

The three terms, plainly

Low spot

A low spot is metal that still sits below the panel's original contour — the remains of the dent. It can be the untouched original damage or, more often after a partial repair, a shallow residual dish that only appears when you look along the panel at an angle. Under a reflection board, a low spot makes the reflected line bow inward and slow down as it crosses the area.

High spot

A high spot is metal pushed above the original contour — the opposite error. It happens when pressure from behind goes too far, or when the center of a dent is lifted before the perimeter has been released. Under a line board, a high spot makes the reflection bulge outward and the line accelerate. To the hand, it feels like a small raised pimple. High spots are more visually offensive than lows of the same depth, because human vision reads a convexity on a curved panel as an obvious wrongness.

Tool mark

A tool mark is a small, localized deformation left by the tip of the PDR rod itself — typically a cluster of tiny circular pushes where the tool was placed in the same spot repeatedly, or a short line where it dragged. Individually they are minute. Collectively, in a cluster, they produce the stippled or orange-peel-like texture that identifies rushed work at a glance under proper lighting.

Why they happen

One pattern runs through the whole table: almost every defect is a consequence of doing in one move what should be done in twenty. Correct PDR is a large number of very small pressures, worked from the outside of the dent inward, with constant reference to the reflection. Our guide on how paintless dent repair works covers the sequence in more detail.

Why the finishing stage takes so long

Lifting a dent is the fast part. A technician with access to the back of a panel can bring the bulk of a hail dent up in a fraction of the total job time. What follows is a loop: push slightly, read the reflection, tap a high back down, read again, adjust, read again. Each cycle changes the surface by an amount smaller than a sheet of paper.

This is also why dent count matters more than dent size on a hail job. Fifty shallow dents on a hood are fifty separate finishing loops, each with its own perimeter to release and its own reflection to verify. That is a real driver of both price and time — see our PDR cost guide for how the ranges work — and it is why full-vehicle hail repair typically runs about 5–10 business days in the shop.

How the panel gets read

At our Plano shop the reading is done under LED line boards — a striped light source reflected across the panel and viewed at a shallow angle. The technician is not looking at the metal. They are watching what the stripes do:

• Straight, evenly spaced lines mean the surface matches its intended contour.
• Lines bowing inward and bunching mean a low.
• Lines bulging outward and stretching apart mean a high.
• Lines with a stippled, broken texture mean tool marks or ripple.
• A halo of distortion around an otherwise flat area means stretched metal — extra material that has to go somewhere.

The same board is used again at quality control. Finished work is signed off by whoever runs quality control and that sign-off is visible in your customer portal.

How each defect is corrected

1. Residual lows are simply continued work — more small pressures from behind, with the perimeter released first so the metal has somewhere to go.
2. High spots are tapped down from the face with a blunt tool and a knockdown, in light repeated blows rather than one hard hit. This is the step DIY attempts almost never include, and its absence is why home repairs so often end with a bump instead of a dent.
3. Tool marks are blended: the technician works the surrounding area up to the level of the marks rather than trying to push the marks themselves out, which would only deepen the pattern.
4. Ripple is treated as one large defect, not many small ones — worked across the whole affected zone so the surface averages back out.
5. Stretched metal with a raised crown may need controlled shrinking, or an honest conversation about refinishing. Panels sometimes do need replacement and refinishing, and the right answer is what is best for the vehicle.

Where these defects come from outside the shop

A large share of the high spots and crowns we see arrived before the car did. Glue-puller and suction-cup kits work by applying one strong pull at the center of a dent — precisely the move that lifts the middle while the perimeter stays trapped, producing a crown around a bump. Slide hammers and dent-pulling tabs concentrate force even harder. None of these kits include the tap-down step that would correct what they create. Our guide on why DIY dent repair kits do not work covers the products in detail.

The practical consequence: every failed attempt makes the professional repair longer, more expensive and less certain. A clean untouched dent is the easiest thing in the shop. The same dent after two hard pulls may no longer be a paintless job at all.

Common misunderstandings

• "A high spot means they ruined it." Usually not. A high spot on a finished repair means the work is unfinished, and tapping it down is routine. Cracked paint over the high spot is the genuinely serious version.
• "If I cannot see it in the parking lot, it is fixed." Flat, shaded light hides a large share of remaining damage. Direct sun or any hard-edged reflection tells the truth.
• "Tool marks mean cheap tools." More often they mean a rushed process. Patience, not equipment, is the main variable.
• "Every dent should come back one hundred percent." Most do. Some do not, and repairability depends on paint condition, metal stretch, panel access and prior repairs. A shop should tell you which of your dents are in the second category before starting.

What to do next

If you are collecting a car after PDR, inspect it in direct sunlight, look along each repaired panel rather than at it, and run a clean dry hand over each repair. If you find a low, a high or a cluster of marks, name it — those three words are all the shop needs to know what you have found and to put it right.

At DentPicks in Plano we read panels under line boards before and after the work, and our repairs carry a written lifetime warranty for as long as you own the vehicle, which is not transferable to a later owner. You can see finished panels in our before and after gallery, or read how our dent repair process runs from first inspection to delivery.

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