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GK Concentrated Fungicidal Wash 1Ltr

Name: GK Concentrated Fungicidal Wash 1Ltr
Brand: GKProductsUK
SKU: CHE / R313/A / 1LTR
Price: 7.20 GBP
Availability: InStock

SKU: CHE / R313/A / 1LTR Brand: GKProductsUK

£7.20 Ex VAT: £6.00

GK Concentrated Fungicidal Wash is a professional-grade biocide treatment for mould, algae, lichen, and fungal growth on interior and exterior surfaces. Apply before painting or decorating to eliminate biological contamination at the cellular level, the root cause of premature paint failure. No rinsing required. One litre makes five litres of treatment solution, covering up to 40 square metres.

What Is Fungicidal Wash and Why Does It Matter?

A fungicidal wash is a biocidal solution applied to surfaces affected by mould, algae, fungal growth, or lichen before cleaning, painting, or decorating. Its purpose is not simply to remove the visible staining, but to kill the biological organism responsible for it at a cellular level, preventing rapid regrowth after the surface is treated.

This distinction is critical. Most people who discover mould or algae on a wall respond by cleaning it off or painting over it. Neither approach addresses the underlying problem.

Biological organisms that are cleaned away without biocidal treatment regrow from surviving spores within weeks. Paint applied over living or recently active biological contamination fails prematurely from peeling, bubbling, discolouring, and harbouring odour, because the organisms continue growing beneath the paint film, breaking the bond between the coating and the substrate.

A properly applied fungicidal wash eliminates this problem before paint goes on, ensuring the decoration performs as intended and lasts as long as it should.

GK Concentrated Fungicidal Wash is a broad-spectrum surface biocide for use against fungal and algal growth on hard surfaces. It kills mould spores, algae, lichen, and bacterial contamination, eliminating 99.9% of biological growth. Unlike bleach-based alternatives that merely bleach visible staining while leaving organisms alive, it destroys the growth at a cellular level for genuinely long-lasting results.

Fungicidal Wash for Exterior Walls: Why Outside Needs It Most

External surfaces are particularly susceptible to biological growth. Render, brick, masonry, pebbledash, and painted exterior walls are exposed to the persistent damp conditions from rain, condensation, morning dew, and poor drainage, all of which create ideal conditions for algae, mould, and lichen to establish.

North-facing walls and surfaces in shaded areas are especially prone. Once biological growth is present on exterior walls, it spreads progressively, holds moisture against the surface, and accelerates weathering and deterioration of the substrate beneath.

Using a fungicidal wash for exterior walls before repainting or rerendering is not optional if biological growth is present. It is the essential first step that determines whether the subsequent decoration will last. Without it, the growth that caused the problem continues beneath the new coating and paint failure follows within months.

GK Concentrated Fungicidal Wash is suitable for use on all common exterior building materials including:

Render and pebbledash: including monocouche, sand and cement, and painted render finishes
Brick and masonry: external walls, boundary walls, outbuildings, and garden structures
Concrete: walls, floors, and hard-standing areas adjacent to buildings
Natural stone: including sandstone and limestone used in external wall construction
Timber: fences, gates, exterior joinery, sheds, and outbuildings
UPVC: fascias, soffits, cladding panels, and window surrounds

Internal Fungicidal Wash: Treating Mould Before It Returns

GK Concentrated Fungicidal Wash is equally suited to internal use, making it the versatile professional's choice for properties where both interior and exterior biological contamination needs addressing. Common internal applications include:

Bathrooms and shower rooms: where high humidity and poor ventilation create persistent mould conditions on walls and ceilings
Kitchens: condensation on cold external walls and around windows
Basements and cellars: where rising damp or poor waterproofing creates conditions for heavy fungal and algal growth

For internal use, ensure adequate ventilation during and after application and allow the surface to dry completely before painting.

For easy application, and in the home, you can try our spray version of GK Mould & Mildew Remover!

The Self-Neutralising Advantage: No Rinsing Required

The most significant practical advantage of GK Concentrated Fungicidal Wash over traditional fungicidal treatments is its self-neutralising formula. Conventional fungicidal washes require thorough rinsing after application, a time-consuming process that introduces large volumes of water to the surface, risks saturating the substrate, and leaves residues that must be removed before painting can begin.

GK Concentrated Fungicidal Wash requires none of this. Apply the diluted solution to the surface, allow it to evaporate naturally, and once dry the surface is ready for painting. No rinsing. No neutralisation step. No risk of water damage from excessive washing down. No residues to remove.

For decorating professionals, this saves hours of labour on every project. For homeowners tackling a damp wall or bathroom ceiling, it removes an entire stage from the process.

Concentrated Formula: Exceptional Value

At a 1:4 dilution ratio, one litre of GK Concentrated Fungicidal Wash produces five litres of ready-to-use treatment solution, covering up to 40 square metres. On heavily infected surfaces, a second application is recommended, but even so, the concentration factor means the cost per treated square metre is significantly lower than ready-to-use alternatives.

The product can be applied using a brush, roller, garden pump sprayer, or watering can. Whichever suits the job and the scale of the surface being treated. It's acid and bleach free throughout, meaning it will not etch, discolour, or damage any common building material.

Apply in dry conditions and allow it to evaporate naturally.

Free delivery on orders over £60. For advice on your specific surface or application, call 07557 111 297 or email sales@gkproductsuk.com.

Key Features

Kills 99.9% of biological growth: broad-spectrum biocide effective against mould, algae, lichen, fungal growth, and bacterial contamination, targeting organisms at the cellular level rather than bleaching surface staining
Self-neutralising: no rinsing required. Apply, allow to evaporate, and paint. No washing-down stage, no neutralisation step, no risk of water damage or residue
Interior and exterior use: a single product addresses biological contamination on internal walls, ceilings, and damp areas as well as external render, brick, masonry, timber, and UPVC
1:4 dilution: one litre makes five litres of treatment solution, covering up to 40m²
Acid and bleach free: will not etch, oxidise, or discolour any common building substrate
Prevents paint failure: eliminates the biological contamination that causes premature peeling, bubbling, and staining under new paint films
HSE Licence No. 10766: UK-regulated biocidal product verified by the Health and Safety Executive
Inhibits regrowth: creates an environment hostile to biological recolonisation, extending the period before retreatment is required

Application Guidelines

Step 1: Preparation

Remove loose dirt, grease, and any coatings that have already failed. Scrape off heavy accumulations of moss, lichen, or mould growth using a stiff brush. The surface does not need to be pristine at this stage as the fungicidal wash will address remaining biological contamination, but removing loose material allows the product to make direct contact with the substrate.

Step 2: Dilution

Dilute one litre of GK Concentrated Fungicidal Wash with four litres of clean water to create five litres of ready-to-use treatment solution. Do not exceed this dilution ratio. For heavily infected surfaces, use at a stronger 1:3 ratio to increase biocidal activity.

Step 3: Application

Apply the diluted solution generously and evenly across the entire surface to be treated, ensuring the substrate is fully saturated. Apply by brush, roller, garden pump sprayer, trigger spray, or watering can. Whichever is most practical for the surface area and access conditions. Apply in dry conditions. Avoid application in rain, frost, or when temperatures are below 5°C.

If plants are nearby, water them well and cover with waterproof fleece before applying. If accidental overspray onto foliage occurs, rinse immediately with clean water as the product may temporarily scorch foliage but will not kill established plants.

Step 4: Evaporation

Allow the solution to evaporate naturally. Do not rinse. Once the surface is dry, it is ready for painting or decoration. No neutralisation, washing-down, or waiting period is required beyond the natural drying time.

Step 5: Repeat if Necessary

On heavily infected surfaces or in cases of severe biological loading, a second application is recommended. Allow the first application to dry fully before retreating.

Storage

Store in the original unopened container in a clean, dry
area for up to 24 months from the date of manufacture. Do not store below 5⁰C.

Download Spec Sheet PDF

Frequently Asked Questions

A fungicidal wash is a biocidal solution applied to surfaces affected by mould, algae, lichen, or fungal growth. It kills the biological organisms causing the problem at a cellular level, not just removes visible staining. You need a fungicidal wash any time you're painting over a surface that has or has had biological growth on it. Painting over contaminated surfaces without treating first causes premature paint failure because the organisms continue growing beneath the paint film.

es. GK Concentrated Fungicidal Wash is specifically designed as a fungicidal wash for exterior walls and is effective on all common external building materials including render, brick, masonry, stone, pebbledash, timber, and UPVC. External surfaces are among the most common applications, as outdoor conditions such as persistent damp, limited sun exposure, and airborne biological contamination, make exterior walls particularly prone to algae, lichen, and fungal growth.

o. GK Concentrated Fungicidal Wash is a self-neutralising formula. After application, simply allow the surface to evaporate and dry naturally. Once dry, it is ready for painting with no washing down, neutralisation, or rinsing required. This is a significant advantage over traditional fungicidal washes, which require a full rinse-down stage before decoration can begin.

Yes. Once the treated surface has dried naturally, it is ready to paint. There is no need to neutralise, rinse, or wait beyond the natural drying period. This makes GK Concentrated Fungicidal Wash particularly efficient for decorating projects where minimising downtime between preparation and painting is important.

Yes. GK Concentrated Fungicidal Wash is suitable for internal use in bathrooms, kitchens, basements, and other areas affected by mould or damp. Ensure adequate ventilation during and after application and allow the surface to dry fully before painting. Wear appropriate PPE such as protective gloves and eye or face protection during application.

The biocidal treatment creates an environment hostile to biological recolonisation, significantly extending the period before regrowth occurs compared to untreated or simply cleaned surfaces. The exact duration depends on the conditions driving the growth. In areas of persistent damp or condensation, the underlying cause should be addressed alongside the surface treatment for the longest-lasting results. Annual treatment as part of a pre-decoration maintenance routine is recommended for surfaces in particularly high-risk environments.

Provided the product is not sprayed directly onto foliage, established plants and lawns are not at risk. If nearby planting cannot be avoided, water plants thoroughly and cover with waterproof fleece before applying. Any accidental overspray on foliage should be rinsed immediately with clean water as it may cause temporary scorching but will not kill established plants and lawns recover quickly.

GK Concentrated Fungicidal Wash is safe on all common building substrates including render, pebbledash, brick, concrete, stone, masonry, timber, UPVC, and painted surfaces. Because it is acid and bleach free and acts only on living organisms, it has no impact on non-living substrate materials.

Why us

Why Choose GK?

We believe in constant innovation. Our team is dedicated to finding new and better solutions that the industry needs, providing the most effective, least harmful, and safest professional-quality products to our customers.

We use high-quality active ingredients that deliver superior, longer-lasting results. By avoiding harsh chemicals, we ensure a safer cleaning process for surfaces and substrates, as well as for the environment. Whether you're an industry professional or a DIY enthusiast, you can expect our products to provide a thorough, lasting clean that leaves your surfaces pristine.

So if you're tired of products on the market delivering a sub-par clean, want to experience professional-quality results, or even find comfort in knowing that your cleaning products are safer for your surfaces and the environment, then why not try our range of GK cleaning products for yourself?

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