Can Ceramic Coating Help Prevent Mildew on Caravan Roofs?

Caravan and RV owners often ask whether ceramic coating can help with black mildew and mould, especially on roofs that sit outdoors year-round under trees and exposed to the elements.

The short answer is yes — with the right expectations and preparation.

This article explains how graphene ceramic coating works on fibreglass and gel coat, and why it’s an effective long-term protection option for caravans, RVs, boats, jet skis and horse floats.

The Reality of Fibreglass & Gel Coat Surfaces

Fibreglass gel coat may look smooth to the naked eye, but under magnification it’s anything but.

At a microscopic level, gel coat is porous and uneven, more like a rugged landscape than a flat surface. Over time, exposure to:

• UV radiation

• Rain and moisture

• Tree sap

• Atmospheric fallout

• Repeated washing

causes the gel coat to oxidise, leaving behind a chalky residue. These pores and surface irregularities create ideal conditions for dirt, organic matter and mildew to cling and grow — which is why caravan roofs are so prone to black staining.

What Ceramic Coating Does — and What It Doesn’t

It’s important to be clear upfront:

Ceramic coating is not an anti-mildew or anti-mould treatment.

It does not kill mildew, and it does not contain fungicides or biocides.

What it does do is change the surface itself.

Graphene ceramic coating:

• Bonds to the gel coat rather than sitting on top

• Fills microscopic pores and surface irregularities

• Creates a smoother, lower surface-energy finish

With fewer pores and less texture:

• Dirt has less to grip onto

• Moisture doesn’t linger as easily

• Mildew and mould struggle to adhere

In simple terms, there’s less for the mildew to stick to.

Why Preparation Makes a Big Difference

Before applying ceramic coating, many professionals will cut and polish the gel coat to remove oxidation and level the surface.

This step:

• Reduces surface porosity

• Improves gloss and clarity

• Allows the coating to bond more effectively

Cutting and polishing is not mandatory, but it does deliver the best possible result.

If the surface isn’t cut:

• Ceramic coating can still be applied

• Multiple coats will gradually fill remaining pores

• Results are still very noticeable, just not fully optimised

Preparation doesn’t change what the coating does — it improves how well it can do it.

If you need help with the preparation process, we have many deteailers who have experience in this area like Jacky @boostdeatilingnz

Why Ceramic Coating Outperforms Waxes

Traditional waxes:

• Sit on the surface

• Wear away relatively quickly

• Offer limited resistance to environmental contamination

Graphene ceramic coatings:

• Chemically bond to the gel coat

• Seal the surface at a microscopic level

• Deliver significantly longer-lasting protection

With correct application and reasonable care, Hermosa Graphene Ceramic Coating can provide protection for up to five years, making it particularly well suited to caravans and RVs that live outdoors.

How Much Product Is Needed?

For a typical caravan roof (around 7 metres long by 2 metres wide), one Hermosa Graphene Ceramic Coating Kit is more than sufficient to complete the job.

Our professional detailers regularly use this coating on caravans, horse floats and boats with excellent long-term results.

The Takeaway

Ceramic coating won’t magically eliminate mildew — but by sealing and smoothing the surface, it dramatically reduces the conditions that allow mildew to form in the first place.

For caravans exposed to trees, moisture and the elements, graphene ceramic coating is one of the most effective long-term protection options available.

If you have questions about preparation, application, or whether ceramic coating is right for your vehicle, we’re always happy to help.