Walking out to your car and seeing mold growing all over it is enough to concern anyone. Mold can start to grow on your car for a number of reasons but it’s mostly down to neglect.
There are 3 types of contaminants that you’re likely to see growing on the exterior of your car. Algae, moss, and mold. The first two are pretty easy to remove. Mold can be a little trickier, especially if it’s “Artillery Fungus“
In this article, I’ll tell you everything that you need to know to remove mold from your car exterior. I’ll also tell you how to prevent it from happening again.
Table of Contents
What Causes Mold On Car Paint
The cause of mold is the same, regardless of the location. What causes mold in and around a building, will also cause mold to grow in and around a car.
Mold needs a food source, moisture, and oxygen to grow. As your car is sitting outside, it’s being subjected to moisture and oxygen at all times. As soon as you add a food source into the mix, you’ll start to see mold growing.
For vehicles, the most common food sources are rain, tree sap, and bird poo. These are all full of minerals and contaminants that encourage growth.
The first place mold grows on cars is around the seals, particularly window seals. Moisture gathers between the door and the belt molding, leading to discoloration and growth of mold.
If you let this snowball without taking action, you’ll soon start to see your car covered in mold. It’s not uncommon to see this with cars left on driveways, or at the side of a house in the bushes.
Poorly stored classics are by far the most likely cars to be covered in mold.
Why removing mold from your car paint is important
At the beginning of its life, your car is treated to protect it from the environment.
There are many ways manufacturers and restoration places protect cars from the environment. The most common is hot-dip galvanization.
Another protective layer is the paint. Your car paint will help to shield your car from the environment, stopping tree sap and other contaminants from damaging your car.
If you leave tree sap, bird poo etchings, or any other contaminants on your car for a long time, they will start to damage the paint. They begin to “etch” into the lacquer, leaving very obvious defects and can even lead to lacquer peel.
The same goes for mold. Leaving mold to spread on the exterior of your car is going to absolutely destroy the paintwork.
In the best-case scenario, you’ll be able to restore the paint with polish. If you leave it too long, you’ll be looking at respraying the car and potentially replacing panels if it leads to rust.
Mold can also take a toll on your health, but it’s more likely to affect you if you have a moldy car interior.
How to remove tree mold & mildew from car paint
Most of the time, all that the car will need is a proper wash.
A full 5-step car wash will be enough to clean cars that are regularly used.
The big problems come when a car is left to rot in a garden, damp area or even at the side of a house in the trees. If this is the case, you’ll need to put in a lot more work during & after washing the car.
To wash the car, you don’t need anything special:
- Pressure Washer
- Foam Cannon / Snow Foam
- Microfiber Wash Mitt
- Car Shampoo
- Microfiber Towels
If you don’t have a pressure washer, it’s not necessary. It just makes the job a lot easier. You can do just fine using the two bucket wash method with grit guards, a strong shampoo, all-purpose cleaner or degreaser.
Follow the steps below to learn exactly how I would do it:
- Remove large contaminants – Before even thinking about using water or products to clean the car make sure any leaves, branches, or mulch are removed from the car.
These things are much harder to remove when they’re wet so it’s best just to get them out of the way.
Most of the time they’ll gather in the scuttle panel, on the roof, or in any other gap. Make sure not to drag these across your paint, they could create scratches. - Pre-Wash The Car – Pre-washing the car is a must. Whether you pre-wash it with snow foam, traffic film remover or another product doesn’t matter.
If the vehicle is covered In stubborn dirt or grime using pre-wash will loosen up the dirt and lubricate the panel to prevent scratching.
After you’ve performed the pre-wash stage and rinsed the car off you should already see the mold, mildew, and algae starting to come off the vehicle. - Perform A Contact Wash – Depending on how much mold is remaining on the car, you may want to use a stronger product than shampoo.
Using a strong shampoo such as CarPro Reset or Meguiars NXT Generation Car Wash is normally enough. If it’s really dirty you may want to use an all-purpose cleaner, bug & tar remover, or even a degreaser.
Make sure to clean the wash mitt as you go, you don’t want to keep dragging contaminants across your vehicle as you work.
Once you’ve gone around the vehicle, rinse it off and see what mold remains. - Spot Clean Any Remaining Mold – If you performed a full wash by now and there is still mold remaining, the best solution is to try and spot clean the area.
If you performed a wash using shampoo, the next logical steps would be to use an APC solution, degreaser, or even bug & tar remover. - Dry The Car – Once I’m satisfied that all of the mold is removed, I’ll wipe away any remaining product and dry the car.
You may not be finished though! If the mold has sat on the car for a long time, it’s probably left behind etching. To remove this you will need to clay bar and polish the car.
Using a Dual Action Polisher would be the best option, but you can also remove swirls and etching by hand.
If you’re on a budget, you can use “ItStillRuns” guide which will tell you how to remove mold from car paint using only household items.
While it’s much easier and safer to use the products and equipment I listed above, I appreciate that not everyone has the means to do so.
How to remove green algae from car window seals
One of the most common problems you’ll face when detailing older cars or barn finds is mold and mildew growing on car window seals or other rubber seals around the vehicle.
These are the worst for it since there’s a slight gap between the seal and the door panel. Over time, this collects dirt and other contaminants creating a breeding ground for mold and algae.
Cleaning and restoring the trim can be incredibly tedious, however, it’s very important that you make it look good again. A dirty, moldy, fading trim piece detracts massively from the overall look of a car.
If you can’t restore it, you could always replace the seal. This tends to be expensive and depending on the age of the car, it could be a rare part.
Using the products, equipment, and methods below, you’ll be able to bring car window trim and other trim pieces back to life.
- Magic Eraser
- Microfiber Towel
- Soapy Water Solution
Before you use the steps below make sure that you’ve washed the area and tried to clean it properly. You may find that with proper cleaning, you don’t actually need to use a magic eraser.
That being said, the steps are fairly easy and it’s very hard to get it wrong.
Make sure that the magic eraser doesn’t touch the paint as you work. I use my finger as a guide but you could even use masking tape to block the painted areas off if you wish.
- Saturate your magic eraser pad – Use a soapy solution or all-purpose cleaner and spray the bar a couple of times. This will provide lubrication and stop you from causing any unnecessary damage to the trim.
- Rub the trim using your eraser pad – After you’ve applied some soapy water or product to your pad, rub it back and forward on the moldy trim to clean it. Make sure to angle the block or pad so that it doesn’t scrub your window or paintwork.
- Wipe away the foamy residue – Once you’re satisfied that you’ve removed the mold from the trim simply wipe away the foamy residue that the eraser bar created.
I personally like to rinse the area and then wipe it with a microfiber drying towel, preparing for the final step. - Apply Plastic Trim Dressing – While the magic eraser bar does a great job at cleaning the mold from the trim, it will probably still look a little dull and faded.
Applying Chemical Guys VRP, T1 Tire N Trim or Meguiars Hyper Dressing will help to bring it back to life.
Removing Artillery Fungus / Shotgun Fungus
Artillery Fungus, also known as shotgun fungus, is not that common. However, if you do happen to find it on your car here’s what to do.
This fungus can be confused for tar spots and vice versa. Artillery fungus is usually found in wood type mulches and can shoot its spores for up to 20 feet.
As much as it’s annoying, it’s rather cool that a plant can make your car dirty without even touching or even being close to it. That said, It’ll also make you think twice about parking within 20 feet of plants or trees.
Cleaning artillery fungus from your car is a process of elimination. You should start off by trying traditional methods, but you’ll probably end up having to use paint cleaners or even plastic razor blades.
You should always start off using the safest method first and progressively work your way up to the most abrasive.
The general idea is that you should get rid of these as soon as possible. The quicker that you do it, the less risk that is involved.
My process for removing artillery fungus after washing a car is:
- Spray All-Purpose Cleaner onto the Panel
- Clay bar the majority of the fungus
- Remove any remaining artillery fungus using my finger nail or plastic razor.
It’s not a nice process, however, it gets results and that’s all that really matters.