Decades-old underbody coating, hardened grease, wax and dirt in every corner: if you want to get a Beetle, Bus or other classic car clean, you'll quickly spend days under the car with a wire brush and scraper, risking destroying more than you save. Dry ice blasting solves exactly this problem: it removes the contamination without attacking the substance. We use the process in our workshop in Rahden for our own projects and offer it as a service for customer vehicles. Here you'll learn how it works and what you can realistically expect.
How Dry Ice Blasting Works
In dry ice blasting, dry ice particles are blasted onto the surface with compressed air. What gets removed is whatever sits on the surface: old soot, hardened grease, wax, loose paint and underbody coating residue, sealants. The surface itself remains untouched. That's the key difference from sandblasting: intact paint stays on, and rust isn't removed either. Dry ice cleans – it doesn't grind.
To make this work well on delicate parts, the process can be finely tuned. Particle size and pressure are regulated across several levels, and there are different nozzles: a wide one for large areas and delicate zones like plastic parts or sensitive paint, and a targeted one with more pressure for stubborn contamination. Caution is required with plastics: the cold can make them brittle and crack, so those areas are worked with less pressure and more distance.
▶ Watch on YouTube: Trockeneisstrahlen
Note: The videos are in German — the article covers all key points in English.
What You Can Realistically Expect
Dry ice is no magic wand. A good example is two gearboxes we show in the video: on one, almost everything came off after a relatively short time and the result looked really good. On the other, the contamination sat so stubbornly that even after considerably longer work the surface never turned pretty – yet it was clean and ready to install. Depending on the part, a cleaning like this takes half an hour or two hours, and how nice the result looks in the end depends heavily on the substance underneath.
Dark discoloration in the metal or burnt-in spots remain visible. If you want a truly like-new surface, there's no way around conventional blasting. But for installation in a normal vehicle, dry ice cleaning is entirely sufficient in most cases.
Practical Example: Split-Window Beetle with Centimeter-Thick Layers
How much the process can deliver is shown by a split-window Beetle that was prepared for reconditioning at our shop. On the floor, the dirt sat centimeters thick in places, plus an extremely hard old underbody coating that's nearly impossible to work off by hand. With dry ice, both came off – the complete floor took around five hours. For comparison: with a scraper and wire brush, that would have been many days of work.
The result is honest: the rust that was hiding under the dirt is clearly visible afterwards. But that's exactly where the value lies. After the cleaning you have a clean assessment and can see which panels really need repair and which are good. Disassembly becomes easier, the repair can be planned precisely, and depending on the customer's wishes, the car is then partially welded and sealed or completely restored.
▶ Watch on YouTube: Brezelkäfer wird mit Trockeneis gestrahlt
Practical Example: T1 Samba Barndoor
A particularly valuable vehicle like an early T1 Samba also shows what the process is meant for. The bus was restored in the 80s and looked very good from the outside. For the cleaning we covered it completely, because the falling dirt makes a proper mess, and blasted the entire underbody with the wide nozzle, including the wheel housings. So that every corner was truly reachable, even the front axle came out.
What emerged was surface rust from four decades – not a pretty sight, but an honest one. Loose dirt and loose residue are completely gone, and that's exactly the basis for resealing the bus with a proper anti-rust primer and preserving its condition for the long term. Not every car shines like new after dry ice blasting. But afterwards you know exactly what you have, and you can conserve the vehicle properly instead of hiding problems under old layers.
▶ Watch on YouTube: T1 Barndoor Samba Trockeneisreinigung
Booking Dry Ice Cleaning at Knepper
We offer dry ice cleaning as a service, for Beetle and Bus just as for Porsche and other classics. Typical use cases: the underbody needs cleaning and resealing, the engine bay should be clean before maintenance, or a vehicle should be honestly assessed before a restoration. We'll also tell you openly if the process makes little sense for your vehicle, because that varies from car to car.
You'll find all the information on our dry ice cleaning page. The easiest way to book an appointment is via our contact page – we'll look at your vehicle and discuss what makes sense. With over 30 years of Beetle experience, we can also assess right away what the next steps after the cleaning would be.
Conclusion
Dry ice blasting is the gentlest way to get a classic car truly clean: dirt, grease, wax and loose layers disappear while paint and substance are preserved. It won't turn a rusty floor into a new one, but it shows you honestly what you're working with – and exactly that is worth gold before any sealing or restoration.
You'll find more insights like this on our YouTube channel.