Do homemade convertible top cleaners work?
A homemade cleaner will not work as well as a purpose made convertible roof cleaner.
Soaps and detergents are not a new technology, and the chemists who design them are practised, have generations of experience to build upon and are very good at formulating a detergent which can loosen the organic and inorganic compounds which have found their way into your hood.
Even so, if you have read any of the other entries about hood cleaning on this knowledge base, you should already know that cleaning hoods is challenging and hard work. It would be unwise to put yourself at a further disadvantage by attempting it with vinegar and baking soda. Or worse, risk damaging your fabric hood by creating blends of powerful cleaners designed for cleaning drains or brickwork. Other products like Milton Fluid may bleach stitching and weaken the fibres.
You should also consider that bleaches and acids will likely remove whatever is left of the protective coating, so definitely not for everyday use.
It is important to consider, that convertible roofs have a lot of rubber seals which stop your roof leaking. The fabric hood is just cosmetic and covers the neoprene layer which is your waterproof barrier. Many hoods are trimmed with a polished aluminium to look like chrome. All these components are delicate and can be damaged or destroyed by harsh chemicals.
So it is best not to cheap-out when it comes to cabriolet hood cleaners. Hood cleaning kits are readily available, not particularly expensive and will come with a weatherproofing coating which you need to protect your hood once it's cleaned.
It bears repeating, that cleaning hoods is hard work, and there is no magic bullet to make your life easier, that the car care industry is hiding from you.
Homemade convertible top cleaner
If you are intent in making a homebrew, we should consider what we are trying to achieve. What is our substrate and what is the nature of the dirt. This will determine what kind of cleaning agents we want to put on the roof.
The first thing to consider is that the roof is a fabric. Unless you have real mohair, or a very old vintage vehicle with a painted canvas roof, then it's likely made of some kind of polymer/plastic such as polyester. Although hard-wearing compared to natural fibres, it is still fairly delicate, and so you should avoid strong bleach or harsh chemicals which may weaken the fibres.
Next we need to consider the dirt. It will consist of dust which contains organic material and trace elements of minerals, which create a very fertile substrate for things like moss and lichen to grow in. Therefore, we are not attempting to remove grease and oil, so do not require strong acidic cleaners. Therefore, we can rule out things like white vinegar and kitchen cleaners.
Therefore, we would recommend using a liquid, biological laundry detergent*. These contain protease enzymes which will eat away at the organic matter within your hood. Enzymes require a bit of heat to work, so we would suggest cleaning your hood on a hot sunny day, and using the water which is as warm as you can bear to dip your hands in. A laundry detergent will also contain the ingredients needed to help lift dirt out of fabric.
At this point, we need to state the blindingly obvious. You know that you can't just spray your clothes down with laundry detergent, and they become clean. That washing machine is doing a lot of work over a 50-minute cycle, and it's no different when cleaning a cabriolet roof. While you may have spent several hours scrubbing your hood with a soft brush, how long have you actually spent cleaning each bit?
Therefore, you may need to rinse and repeat many times. And then, if you have determined that a liquid laundry detergent isn't getting all the dirt out, you may want to switch to a fabric and upholstery cleaner.
You may be thinking that an upholstery cleaner isn't that much more expensive than a laundry detergent, so why not just start out with the upholstery cleaner? That's a good question!
Upholstery cleaners generally don't contain enzymes which are great for breaking down organic matter, but they may well contain biocides and fungicides which are great at killing organic matter. But they may also 'kill' the enzymes and create an inhospitable environment for them. So it's best to attack with the enzymes first.
You should also be aware that upholstery cleaners often contain optical brighteners. They don't show up much on a black roof, but they can make stains really glow! This can be a curse or a blessing depending on your point of view. If you are determined to wash out every stain, this will make them easier to see, but may come as a bit of a shock if you thought you were making progress.
Once your hood is clean, it will then need a weatherproof hydrophobic coating. Although you can readily get fabric protectors that will do the job, they aren't designed for outdoor use and don't contain the biocides and antifungals required to keep moss and lichen at bay.
*Do not use powdered detergent, it won't dissolve properly, and you will end up with a hood covered in powder.
Written by Danny Argent. Last updated 24/04/2024 15:10
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Cleaning Convertible Car Roofs
It's important that your cabriolet's hood be periodically cleaned and reproofed with the correct products.