Dr. Wack "A1" A1 Cabrio "Verdeck-Imprägnierer" Fabric waterproofing 400ml

Dr. Wack A1 Cabrio "Convertible Top Waterproofer" makes fabric tops water-repellent and allows them to breathe

What is the Dr. Wack A1 Cabrio "Convertible Top Waterproofer"? A 400 ml aerosol waterproofing spray for textile convertible tops made of cotton blends, acrylic, or Dralon. It does not clean, it does not re-dye, and it is explicitly not intended for tops made of soft PVC, vinyl, or synthetic leather.

Dr. Wack A1 Cabrio "Convertible Top Waterproofer" is a textile waterproofing agent from Dr. Wack that coats individual threads rather than forming a skin over the fabric. The manufacturer describes it as follows: the active ingredients wrap around each fiber and, as they dry, stand upright like many tiny umbrellas side by side. The fabric remains open between these umbrellas.

That is the whole difference between waterproofing and sealing. A tarp holds back water because it has no holes. A waterproofed convertible top holds back water because the water no longer wants to wet the fiber: it contracts into a bead with a surface tension of about 72 mN/m and finds no hold to spread out on the low-energy fiber surface.

For you, this means: the gaps in the fabric remain open, allowing air and water vapor to continue passing through. A top that is instead covered with a closed film may keep the rain out, but it also traps moisture inside. Anyone who has ever slept under a plastic tarp knows the result.

• Test winner with measurement protocol. In 2020, KÜS, AUTO BILD, and AUTO BILD Klassik tested ten convertible top waterproofers in a chemical laboratory on identical black top fabric, measuring water repellency over ten cycles on a spray rating tester. The A1 was the only one to receive the rating "highly recommended": water and oil-repellent, residue-free, and easy to apply. Five of the ten products failed.
• Oil bounces off, not just rain. Oil repellency was tested in the same study using oils with surface tensions similar to tree resins. In practical terms, this means that resin, bird droppings, and road film have a harder time sticking, and you don't have to reach for a sponge and foam as often on a fabric that Dr. Wack itself certifies as having low abrasion resistance.
• 400 ml, PFAS-free, not just for cars. Dr. Wack lists the current formula as 100 percent PFAS-free. The can is also approved for awnings, tents, and textile clothing—the items in the same garage as your convertible that need the same moisture protection.

Expert tip from Detailing1: From our experience, one specific process primarily costs you performance: spraying the top in the sun because it dries faster there. Dr. Wack writes the exact opposite in its own care tips. It should be sprayed in a cool, shaded area. Only when the top is well-ventilated should the car be moved into the sun, as the heat facilitates the standing up of the active ingredients. Application takes less than 10 minutes per layer. The sun does the actual work afterward.

Several thin layers beat one heavy application

Shake the can, spray thinly and evenly from a distance of about 20 centimeters, let it flash off, then apply a second thin layer, taking care not to go over already treated areas intentionally.

The reason lies in the mechanics. The active ingredients need to stand up while drying, and for that, they need space and air at the fiber level. Anyone who saturates the surface until it shines causes the product to clump together instead of standing up. Dr. Wack frames this as a prohibition: avoid soaking the sprayed surfaces; it is better to spray thinly several times and allow the product time to dry in between.

Before the first spray, it is decided whether it will hold at all. The top must be clean and completely dry; otherwise, the waterproofing will sit on the dirt instead of the fiber. Surfactant residues are even more treacherous than dirt: the manufacturer explicitly writes that detergent residues prevent any waterproofing effect. After using the Convertible Top Cleaner, rinse until the runoff water remains clear and no white bubbles form anywhere. Afterward, the fabric needs time to dry thoroughly down to the underlayer.

Everything that is not textile must be covered. According to the manufacturer, glass, plastic windows, and paint surfaces should neither be sprayed nor exposed to spray mist. A strip of masking tape along the edge of the top and an old sheet over the rear window are sufficient. Work outdoors in the shade, not on a heated surface or in direct sunlight.

The sequence on the surface itself is unspectacular but important: work in strips, overlapping, from one side to the other. A top is an inclined surface, and a spray jet that dwells on one spot for too long will accumulate into a trickle. Evenly here means: at a constant speed, a constant 20 cm distance, and no dwelling.

Soft PVC is the limit for this waterproofer

According to the manufacturer, this product is not suitable for tops made of soft PVC, vinyl, or synthetic leather; a plastic deep-care product should be used there instead. This is not a matter of preference, but a matter of material.

Soft PVC has no fibers to coat. It is a solid layer that consists of about 40 percent plasticizers, which keep the plastic elastic. If these escape due to UV radiation and weathering, the material becomes brittle and the embedded pigments are destroyed. A vinyl top therefore needs a replenishment of plasticizers, not a water repellent. This is exactly what the Plastic Deep-Care Agent provides.

The test for this is tactile and takes five seconds. If the top feels like fabric, with a visible weave structure and a rough, soft surface, it is textile and this spray is the right choice. If it feels like a smooth, closed film, you are dealing with soft PVC.

The second limit concerns color. The integrated UV protection prevents fading of the top fabric with regular use, but it does not reverse existing fading. Whatever pigment was lost on the sunny side over five summers remains lost. The spray secures today's condition; it cannot buy back what was lost yesterday.

And a note regarding the formulation: repelling oil without fluorine chemistry is the harder part of this task, as fluorine compounds were the easy way for decades. The fact that today's formula is, according to Dr. Wack, free of PFAS and still led in oil repellency in lab tests is the result of the work done in Baar-Ebenhausen.

A factory-new top still shows its beading on its own

Modern top fabrics come waterproofed from the factory, and as long as raindrops remain as beads on them, you simply do not need this can yet.

It is needed where the elements are constantly pressing on the fabric: for a convertible that stays outside or under trees, for a year-round vehicle, or for a car without a garage during the winter. Top fabrics like the three-layer Sonnenland material with Dralon outer fabric, which BMW, Mercedes, and Porsche install as standard, last for many years like new. But you only get those years with proper care.

Anyone who regularly takes their convertible through a car wash should not confuse things: a wax program there is a paint product and works on a smooth, closed surface. A textile top is the opposite of that, and it remains just as unprotected after the wash as it was when it went in.

One 400 ml can covers more than one top. Because the same can is approved for awnings, tents, and textile clothing, the rest won't end up on the shelf, but on the patio awning. If you are looking for the right products for the complete process, you will find cleaners and waterproofers side by side in the Convertible Top Care section.

The question remains when to reapply, and the top itself answers that. There is an intermediate stage between "holding" and "no longer holding," and that is your actual deadline. Freshly waterproofed, the droplets sit as round beads on the fabric; that is beading.

When the effect wears off, the beads fall flat and run off as a continuous film. The scene calls this "sheeting," and on a convertible top, it is a yellow card. Only after that comes the dark, matte spot that remains, which means: the water is sitting inside the fiber.

The difference between the two points in time is a whole extra step. Those who reapply during sheeting spray onto a clean, dry top and are done in half an hour. Those who wait until the dark spot appears must clean it again first, thus introducing exactly the mechanical stress to the fabric that the waterproofing was supposed to save it from in the first place.

Applying the Dr. Wack A1 Convertible "Soft Top Impregnator"

Apply cool, then cure warm

Clean the soft top before impregnation and rinse until the runoff water remains clear and no more white bubbles form. According to Dr. Wack, cleaning agent residues prevent the impregnation from taking effect. The fabric must then dry through to the base layer, not just dry off on the surface. Therefore, it is better to plan for two days rather than one for the soft top cleaner and the subsequent impregnation.

Mask off glass and plastic windows and cover the adjacent painted surfaces. The manufacturer specifies that these areas should neither be sprayed nor exposed to spray mist. For this purpose, park the vehicle outdoors in the shade. The soft top surface must not be heated, and you should not even start in direct sunlight.

Shake the can and spray thinly and evenly from a distance of about 20 centimeters. Work through in overlapping strips, moving at a constant speed and maintaining an equal distance without lingering on any one spot. The surface should be evenly coated, not wet and glossy: soaking the sprayed areas must be strictly avoided.

Allow the first layer to flash off and then apply a second thin layer. When doing so, deliberately avoid going over areas that are already impregnated. Two thin passes with a break in between are more effective than one heavy one, as the active ingredients need to stand upright while drying and require air at the fiber for this to happen.

Let the soft top air out in a shaded place. As soon as it is well ventilated, move the car to a warm, sunny spot. The heat facilitates and accelerates the upright alignment of the active ingredients, providing you with better results without having to buy more products.

Notes: This product is not suitable for soft tops made of soft PVC, vinyl, or synthetic leather; the plastic deep cleaner should be used there. The UV protection prevents further fading with regular use, but it does not restore color that has already been lost. Re-impregnation should not be based on a calendar, but as soon as the drops no longer bead up but run off as a flat film. The same can is also approved for awnings, tents, and textile clothing. Store upright, cool, and not in a heated vehicle.