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Call us on (02) 9986 2126
Call us on (02) 9986 2126
Lichen or black mould on your roof?

Lichen or black mould on your roof?

Wet & Forget is non-acidic, non-caustic and contains no bleach and will not damage any surface.

Here are a few tips for when you apply Wet & Forget to your roof to get rid of lichen and/or black mould:


For an average 3 bedroom tile roof with lichen you would require 3 x 5 litre packs depending on the total area covered with lichen.

For best results mix the Wet & Forget and spot spray the lichen, leave for 10-15 minutes and then respray the lichen and the entire roof to ensure the lichen absorbs the Wet & Forget thoroughly. The first application is to dissolve the waxy surface. The 2nd spray will then penetrate the lichen.

Black Mould

The average 3 bedroom tile roof is approx 150sq mts, but because of the undulations of the tile profile the actual area is a lot bigger. Therefore an average tile/concrete roof would require 2 x 5 litre packs, depending on how porous the surface is and how much biological growth is present. For green moss and black mould one application is normally sufficient. 

Tank Water

If you are on tank water disconnect the water supply to your tank for at least the first 10mm of rain or 2 good downpours to avoid any chance of contamination. Check before reconnecting that the water flowing onto the ground, when raining is not foaming.


Simply dilute as per instructions on the bottle into a household garden sprayer or backpack sprayer.

If badly contaminated, apply a second application one month after the first.

Wet & Forget is best applied in overcast dry conditions to avoid rapid evaporation.  

Spray the affected area to the point of saturation. DO NOT hose off.

DO NOT apply if rain is expected within 6 hours.

Reaction Time

The time it takes for an infested surface to become clean depends on the type and intensity of biological growth.

Black mould and Lichen will take 6-8 months and badly contaminated surfaces can take 12 months.   


Here at Wet & Forget we always promote safety first so always ensure that you are safely harnessed to your roof and never walk on the section you have just sprayed as it will be slippery until it is dry.


Wet & Forget is not systemic or hormone based and is safe around plants, however a slight discolouration may occur if allowed to dry on the leaves of delicate plants. To avoid this, simply mist surrounding plants with water, before and after spraying Wet & Forget.

To shop or read about Wet & Forget, click here.


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Wet & Forget Australia - June 29, 2020

Hi Michael, thanks so much for your comment. To discuss your particular situation, please give us a call on (02) 9986 2126 between 9am and 4pm Mon-Fri so that we can help you out.

Michael - June 29, 2020

We have been asked to spray external walls of a winery to remove black mould.

Which product would be considered as food grade friendly.

The winery is concerned about any adverse effects on its product.

Thank you

Wet & Forget Australia - April 16, 2020

Hi Matthew! For treating any kind of growth on a roof we recommend using Rapid Application as it can reach up to 8m. Rapid Application is safe to use on any exterior surface and therefore is suitable for poly carb roofing. To read more about Rapid Application visit:

mathew knights - April 3, 2020

Hi guys,
What product would you recommend for Lichen on a poly carb roof

Wet & Forget Australia - February 27, 2020

Hi Alex! For mould and mildew that occurs indoors, we recommend the product Wet & Forget Indoor. This product is designed for interior uses and comes in a ready-to-use bottle. You can learn more here:

alex smoulders - February 3, 2020

Very unique and innovative approach in taking out black moulds. Could it be useful in bathroom tiles for Bathroom Renovations?

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