--- title: When a Sydney Used Car Dealer Says "Original Paint," Here's How They Actually Check canonical: https://blog.maxautosydney.com.au/en/when-a-sydney-used-car-dealer-says-original-paint-here-s-how-they-actually-check-8ca0cd8651 --- Colour match is one of the most seductive lies in the used car business. You're standing under the fluorescent lights at a dealership on Parramatta Rd, walking around a silver 2019 BMW 3 Series. Every panel looks the same shade. The salesperson says, "all original paint, no accidents." You want to believe them. The price looks right. The car is clean. You've been looking for three weeks. You buy it. Three months later, a mate pulls out a paint thickness gauge — the same kind every smash repairer has sitting on their bench — and the reading on the front left quarter panel comes back at 280 microns. He moves the probe around the panel: 265, 290, 271. Then he walks around to the opposite side. Right quarter: 108, 112, 105. Every other panel on the car is sitting in that 90–130 range. Someone resprayed that left quarter and didn't bother telling you. Given the location — front left, the side most exposed in a parking lot — you can make your own guesses about what happened before the paint went on. This happens more than people think, and the reason it keeps happening is simple: most buyers look at colour, not thickness. The colour looked consistent. The story sounded clean. That was enough. It wasn't. Here's how paint condition is actually checked — the method, the numbers, and what you can do yourself before handing over a single dollar. --- ## Why colour consistency tells you almost nothing Your eye is surprisingly bad at catching respray, especially in overcast Sydney weather — which, let's be honest, is most of the time. Modern paint mixing technology means a good respray shop can get within a fraction of a shade of the original factory code. The paint supplier pulls the colour formula from a database, matches it to the build code on the compliance plate, and mixes to spec. Under diffused outdoor light or inside a showroom with LED overheads, even an experienced buyer will miss it. What colour *can* tell you is limited to genuinely sloppy work: a panel that's noticeably lighter or darker, a slight orange-peel texture that doesn't match the adjacent panels, or overspray sitting on rubber trims and window seals that someone forgot to clean up. These are real tells — but they only show up when the repair was done cheaply or in a hurry. A respray job done properly, in a temperature-controlled booth, by a painter who takes their time blending the edges, often looks completely flawless to a careful naked eye, even in good light. This is precisely why the conversation about "original paint" has to start with a paint thickness gauge, not a walk-around. ![](https://breezecdn.org/tenants/maxauto/articles/8ca0cd86-51b9-4801-8109-74a7c6963db9/body-0.jpg) --- ## How a paint thickness gauge actually works — and what the numbers mean A paint thickness gauge (漆膜仪 in Chinese, also called a paint depth meter) uses electromagnetic induction to measure how thick the total coating is above the steel panel. It emits a small magnetic field, and the way that field interacts with the metal beneath tells the instrument how much non-metallic material — primer, base coat, clear coat, filler, whatever's there — is sitting between the probe tip and the steel. It doesn't care what colour the paint is. It just reports: there are X microns of material on this panel. Factory paint from a car manufacturer is applied in a controlled environment on a production line — panels go through a phosphate bath, an electro-deposition primer coat, a filler coat, a base coat, and finally a clear coat, all at precise temperatures and film thicknesses. For most modern cars, that entire stack lands in a range of roughly **80–180 microns** for an untouched factory panel. The exact numbers vary by manufacturer, model year, and even the colour (darker colours sometimes run slightly thicker due to extra coats), so treat that range as a guide rather than a hard cutoff. The number itself isn't the whole story. **Consistency across panels is the whole story.** Here's how to read what you find: **Normal variation (same panel, multiple spots):** Factory panels will show minor variation — maybe 10–30 microns across the same door if you probe half a dozen spots. That's completely expected. The electrostatic spray process is consistent but not surgical, and the geometry of a panel means some areas receive slightly more overspray than others. **Repainted panel:** A repair respray adds a new base coat and clear coat on top of whatever the original factory finish was — sometimes on top of a primer coat too, if the original was scuffed back. Suddenly you're reading 200–350 microns on one door and 100–120 everywhere else. That delta is not noise. That's a flag that something happened to that panel and it was recoated. **Filler used (accident repair):** If there was structural damage and body filler — what tradies here call "bog" — was used to reshape the panel before repainting, readings can spike much higher. You'll see 400–600 microns, sometimes more, in localised spots where the filler was applied thickest. Body filler is non-metallic and relatively thick, and it plays havoc with the gauge reading. Some cheaper gauges will give wildly erratic numbers over a filler repair; better instruments stay consistent but the number is still dramatically elevated. **The right way to check:** Probe every major panel in at least 3–5 spots — top, middle, bottom, near the leading edge, and near the trailing edge. Do the bonnet, both front guards, both front doors, both rear doors if it's a four-door, both rear quarters, and the boot lid. Write the readings down as you go — don't try to hold them in your head across a fifteen-panel check. Then compare across the car. Outliers are your story. One important note that trips up a lot of buyers: **aluminium panels behave differently**. Many newer BMWs, Audis, and Jaguars use aluminium for the bonnet and front guards specifically — it saves weight over the axle. The physics of electromagnetic induction changes over aluminium versus steel, and a gauge set to ferrous (steel) mode will give meaningless readings on an ali panel. A quality gauge with auto-detect for ferrous/non-ferrous materials handles this automatically. Cheaper single-mode gauges don't, and an inexperienced check on an aluminium-heavy car can give you a false all-clear. Worth knowing before you trust the reading. --- ## What we look for with our eyes alongside the gauge The gauge tells you *whether* something's been done. Your eyes, used properly, tell you *how* it was done and sometimes *why* — and the two together are considerably more informative than either alone. Run your fingertip slowly along the panel edge where a door meets the front guard, or where the bonnet meets the slam panel. Factory edges are clean, consistent, and slightly sharp — the panel was painted off the car, or at least before final assembly, so the paint wraps neatly around the edge without hesitation. On a respray, you'll sometimes feel a slight ridge or a thickening at the edge, because the painter was working with masking tape and the paint builds up at the tape line. You can feel this before you can see it, once you know what you're looking for. ![](https://breezecdn.org/tenants/maxauto/articles/8ca0cd86-51b9-4801-8109-74a7c6963db9/body-1.jpg) Look carefully at the **door jambs and the inside edges of the bonnet and boot lid**. These surfaces are the single most reliable tell in the whole inspection, and they're also the places a quick or budget respray job almost always skips — they're geometrically awkward to paint, they require masking the latch hardware, and the vast majority of customers never think to look there. If the outer skin of a door was resprayed but the inner edge of that same door still shows the original factory colour underneath, you've found a mismatch that no gauge reading could be clearer about. We've seen cars where the outer door was a slightly warmer shade of white than the jamb — invisible in casual light, obvious when you open the door and look straight at the edge. Check every rubber seal for overspray. Open each door fully, pop the bonnet and the boot, and run your eye carefully along the rubber weatherstripping. In a factory build, the seals go on *after* the painted body has been assembled, so there's no way for overspray to land on them. If you see a fine mist of colour on the rubber — especially near the panel edges — the panel was painted while the car was assembled, which means it was painted after the factory, which means it was repaired. Under strong directional light — a phone torch held at a low angle, parallel to the panel surface rather than shining directly at it — look at the texture of the clear coat. This takes a bit of practice, but factory paint has a characteristic texture that varies subtly between manufacturers. BMW's factory clear coat on their sedans has a particular tight, high-gloss texture. A respray from an independent shop, even a skilled one, often has slightly more orange peel, or slightly less, depending on the spray gun settings, the booth temperature, and the reducer ratio the painter was using that day. It's genuinely subtle — but it's real, and once you've trained your eye by looking at a few cars you *know* are factory, it becomes easier to catch. --- ## The check we run on every car at our workshop Every car that comes into Max Auto — whether it came through an auction, a private seller, or a customer trade-in — goes through a systematic paint check before it goes anywhere near our forecourt. We use a gauge on every panel, log the readings panel by panel, and flag anything that deviates by more than roughly 50 microns from what the rest of the car is showing. If something flags, it goes to the technicians in our M&F workshop for a closer hands-on look. That means checking the corresponding area in the vehicle's documentary history — cross-referencing against the PPSR result and whatever we can pull from NSW Transport's records — and physically inspecting the panel edge, the jamb, the rubber seals, and the underside of the flagged area when the car is on the hoist. A high reading on a rear quarter, for example, tells you something happened; the underside of that quarter, whether the inner lip has any sign of historical straightening or welding, tells you how significant it was. We're not infallible — no pre-purchase process is. We can't reconstruct every minor incident that happened to a car in the years before we got to it, and we won't pretend otherwise. What we can tell you is exactly what the gauge read on each panel, what we saw in the jambs, what the PPSR returned, and what the technicians found when they put it on the hoist. If we identified a repaired panel ourselves and dealt with it before listing the car, we tell you what was done. If we found something we couldn't fully explain — a slightly elevated reading with no corresponding PPSR entry, for instance — we tell you that too, and the pricing reflects it. A car with an unexplained flag doesn't get priced like a clean car. That's the basic standard. It sounds obvious when you say it out loud. It isn't what every car on Parramatta Rd has been through. ![](https://breezecdn.org/tenants/maxauto/articles/8ca0cd86-51b9-4801-8109-74a7c6963db9/body-2.jpg) --- ## What you can do yourself before buying — a short checklist You don't need to own a paint gauge to do a useful first pass. Here's what any buyer can do at a viewing, with nothing more than a phone and your hands: **Bring a torch.** Low-angle light across a panel reveals texture differences that overhead showroom lighting or flat overcast skies completely flatten out. Hold the torch parallel to the panel surface and move it slowly. If one panel has a subtly different texture to the one next to it, you'll see it here before anywhere else. **Check every door jamb.** Open each door fully and look at the inner painted edge. If the outer panel was resprayed, the inner edge will often show the inconsistency — different shade, different texture, or original factory paint with a sharp tape line where the masking ended. **Feel the panel edges.** Run your fingertip slowly along the body line where the bonnet meets the guard, where the door meets the quarter. Uneven edges, slight ridges, or paint buildup at a line are worth noting. **Look for overspray on rubber.** Door seals, boot seals, windscreen and window rubber. Any paint on these means the car was painted after the seals were fitted — i.e., after the factory. **Ask specifically, and ask for it in writing.** Ask the seller directly: "Does this vehicle have any repainted panels? Have there been any accident repairs or insurance claims?" A licensed motor dealer in NSW is legally obligated not to misrepresent a vehicle's condition or history under the Motor Dealers and Repairers Act 2013. Get the answer documented on the contract, not just said over the bonnet. **If you're serious about a car, pay for a pre-purchase inspection (PPI).** A licensed independent mechanic with a calibrated gauge and a hoist, spending an hour on a car you're genuinely considering, runs around $150–$250 in Sydney. Against a $20,000–$50,000 purchase, that's one of the better spends you'll make in the whole process. --- ## One honest caveat A repainted panel isn't automatically a dealbreaker. Plenty of well-maintained cars have had a door ding properly fixed, or a scratch repaired before it rusted, and the car is completely sound. The issue is when a respray is covering something structural — a significant impact that bent and straightened a panel, a repair that used excessive filler to mask frame damage, or a history that doesn't match what the seller is telling you. The gauge and the visual check flag *both* scenarios. It's the follow-up — PPSR, physical inspection of the inner structure, professional assessment — that tells you which one you're actually dealing with. This is also why "original paint" as a simple yes-or-no answer doesn't give you enough to work with. The more useful question is: "What does the paint condition on this specific car tell me about its history, and does that match what the seller is claiming and what the PPSR shows?" If you want to know what we found on a specific car in our current stock — gauge readings panel by panel, what flagged, what we did about it, and what the PPSR came back with — we're happy to walk you through it when you come in. That conversation costs nothing, and it's probably the most useful fifteen minutes you'll spend before signing anything. Come find us on Parramatta Rd in Concord, or send us a message and tell us which car you're looking at. We'll pull the file.