Soft Wash for Silicon Coloured Render . . .

                                                                                          ” Algae, Fungi and Other Unwanted Guests “ 

Complete K REND Cleaning Care / Restoration / Maintenance

Soft Wash For Silicon Coloured Render ...

" Algae, Fungi and Other Unwanted Guests "

Softwashing and it’s many benefits


Nature relentlessly affects the built environment, at its pace until most surfaces are eventually covered with a cocktail of bacteria, fungi, algae, yeasts, protozoa and other microorganisms along with non-living debris and corrosion products. The layer is called a biofilm.

To tackle biofilm growth specialist cleaning method called Soft Wash or Softwashing had to be developed as traditional cleaning system caused damage to the renders or did not work effectively. 

In recent years the popularity of silicon coloured renders has increased dramatically, especially on the more recently built residential blocks of flats and commercial properties. 

However, over time silicon coloured render, also referred to as K Rend, becomes dirty and very susceptible to becoming covered in moss and algae.
The appearance and growth of an organic material on silicon renders is inevitable and if left untreated, if left untreated grows into a much larger problem that could lead to very costly repairs.

Soft Wash or softwashing systems are specifically designed to treat and remove these organic materials and to prevent damage and dirty appearance of the building. 

If your building shows signs of green or red marking do not wait, get the professionals in to tackle the problem straight away. Saving you a lot of hassle and money which could rack up into the hundreds of thousands in repairs if left untreated.
Our team of skilled professionals will clean the render to its formal glory with our specialist cleaning solutions. Our purposely engineered soft wash cleaning equipment and cleaning solutions are approved by K REND. This is to guarantee that this method is the most gentle and the safest cleaning system available on the market today.

Softwash Render Cleaning

The straight forward way of controlling the biofilm is by impregnating the surface with a solution of quaternary ammonium. The product AlgoClear® Pro works on the biofilm by puncturing microorganisms cell walls. It does not interact with the mineral components of self finished renders and does not contain any compound deleterious to the colouring agents or the surface cohesion. In particular, the product has a neutral pH. On porous render, the surfactant active will decontaminate deep into the surface porosity by capillary action.
Green Algae dies within minutes by cell wall puncture. If the algae film is thick, the dead cells display milky sheen for a few hours.

Trentepohlia is a green algae giving away a red dye. Chemically the red marks are a beta carotene and wash away readily under the rain. We sometimes find some grey under the darker red cones: It comes from fungi taking advantage of the light filter provided by the beta carotene. Sometimes, after a prolonged period, there is an accumulation of decayed organic material behind the red, revealed only after the stain has washed. It does not react to additional biocidal treatment. They are dissolved with MetaClear.

Filamentous fungi are characteristic black inverted cones under stone joints, window sills and cornices, or thinly spread over flat surfaces. The black is metabolised by the hypae in the porosity of the render and protects it from UV light. The paste is water soluble and decays by photolyse. Dark metabolites are dissolved with Metaclear.

Biocide purity: It is particularly critical to use a high purity quaternary ammonium on render. Alternative biocides based on bleach or quaternary ammoniums containing impurities/solvents may permanently affect the appearance of the rendered surfaces.
Moulds are a group of filamentous fungi. Their structure enables them to key their filaments in the porosity of render and even rock. As a result, moulds do not self-cleanse as readily as algae. The most common species of fungi on facades are the Cladosporium spp and Alternaria spp. Both metabolise a black pigment protecting them from UV radiations and causing some staining of the surface. Moulds are killed by a solution of Algoclear within approximately one hour. The self-cleansing however can take several months or is helped in a second visit by rinsing with fresh water.

The treatment of moulds is best carried out in steps. First, remove the thick with a scraper until the substrate is clearly visible. Apply a 1/20 solution of AlgoClear® Pro using a soft bristle brush. This helps to soften the biofilm. After brushing, a rapid rinsing with a solution 1/20 AlgoClear® Pro will complete the second step. About 6 weeks after the treatment the black discolorations should have significantly receded.

It is good practice to leave the surface to shed the dead biofilm for 4 weeks to 6 weeks. This gives the superficial stains time to receed, leaving the marks requiring attention more identifiable.

The second visit may consist of a simple pressure water rinsing. The remaining metabolites are not alive. A second biocidal treatment will not succeed in reducing them. To do this a specific oxidising treatment is required.

Water repellents: They are sometimes used on stone or render to help keeping the surface dry. There is no evidence showing water repellents having beneficial effects with regard to the return of contaminants. As with paints, reducing the external porosity may lead to adverse effects on the inner envelope of the building.

Soft Wash Roofs cleaning

Removing the excess growth: Many roofs are cleaned when the moss has become excessive. The bulky material is scraped off using a simple implementation. Below 30° pitch and when the tiles are sound, this can be done by a trained roofer, pacing the roof itself. If the roof is too steep or fragile – period clay tiles for instance – the preparation is carried out from the eaves using bespoke telescopic tools.

The gutter outlets are protected against blockage beforehand. Tarpaulin is laid to receive the falling debris. If the moss balls are small and dispersed, they will fall naturally.

Spraying: The  Spraybox will mix the concentrate on demand, to the correct concentration. The pressure and flow rate of the system are designed to apply the treatment evenly and easily upon the roof surface.

Protection of the planted environment: The active ingredient can leave a discolouration at the point of contact with plant leaves and flowers. Early rinsing has good results but some protection may be needed, particularly in windy conditions. Grass, if affected will recover rapidly.

Other Surface softwashing

AlgoClear® Pro decontaminates stone affected by black ingrained crusts. The concentration is set to 1/20 and a period of 4 to 6 weeks allowed for the etched black incrustations to loose their cohesion and wash away with a bristle brush and water.
AlgoClear® Pro is very effective at cleaning Multi-Use Games Areas and Sports Surfaces.
Whilst reputedly low maintenance, artificial grass needs regular cleaning to avoid infections caused by skin grazing on contaminated surfaces and also progressive loss of drainage. Contact Cropcare for details of the appropriate procedure.
The best way to maintain timber, both structurally and visually is to keep it free from biological contamination. AlgoClear® Pro kills the fungi responsible for dry and wet rot as well as surface blemishes. The wood surface, if exposed to the weather remains silver grey.
AlgoClear® Pro is used widely in the agricultural industry to clean Polycarbonates such as PVC, all polymers and elastomers typically used for Polytunnels and green houses.
  • Bio Degredable 100%
  • Eco Friendly 100%
  • NON BLEACH 100%

The active ingredient is didecyl dimethyl ammonium chloride

DDAC meets the biodegradability criteria of the EU, OCDE and the US-EPA. Data varies with tests specifications, but biodegradability is considered to be of 85 to 90% at 48 hours. DDAC does not bioaccumulate.

AlgoClear® Pro SoftClean
AlgoClear Pro is a high purity quaternary ammonium. It is a biocide working by contact with microbial life. It will act on small organisms by puncturing their cell walls. Its concentration is 40%. High Purity means the product does not contain solvents and will not affect silicone additives / sealants / coatings found in modern construction products. AlgoClear Pro is recommended by K Rend. AlgoClear Pro is surfactant: It is a powerful soap. The product foam on impact at low concentration. It will, when brushed and rinsed, remove grime from a surface as well as sanitising it.

Algoclear Pro does not contain aggressive or oxidising agents such as bleach, acid, lye etc. and is neither corrosive, nor bleaching.


MetaClear is a non penetrating gel formulated for removing black discolouration from render and masonry without impregnation. Brush on and rinse, the gel is fast acting and low odour.

MetaClear lubricates the brush and limits the risk of surface abrasion. The detergency is achieved through the action of sodium hypochlorite and the sequestration of impurities in the gel.

MetaClear is used before or after the AlgoClear treatment. If the surface is too contaminated, it is preferable to open the pores first and soak the render after. In many other instances, the AlgoClear treatment is carried out first and the remaining marks either left to recede naturally, or removed with MetaClear.

The delivery system consists in pumping the MetaClear up a pole into a brush. The product is then rinsed.


OxiClear is a non penetrating brush applied gel for removing metal oxidation marks – iron, copper, lead etc – roofing materials and porous surfaces. OxiClear will also work on non porous surfaces such as GRP, UPVC glass etc. The active ingredient is phosphoric acid, an organic acid at a concentration where the risk to people and material is easily controllable.


GraffiClear removes all types of graffiti. This professional grade formulation can be used on porous and non porous surfaces. Fast and easy to use. Ghost marks are removed with an alkali soap. Water soluble, low odour, non toxic, non caustic, non corrosive and solvent free.


HydroClear is a high performance, deep penetrating sealer for porous brick, stone, render and concrete surfaces. This unique formula gives long lasting protection against water penetration and damage combined with exceptional breathability. UV resistant.

HydroClear is recommended on westward elevations or where the design does not make due allowance for overhangs.


OleoClear is an ultra effective degreaser, removing grease, grime and oil etc from hard surfaces. A superb neutraliser and wash-down solution, its low hazard formulation makes it very safe to use. The product is primarily used in amenity maintenance: Car park, bus stations etc. OleoClear keeps working for several weeks and has a low hazard formulation.

Formation & composition of BioFilm

A Biofilm forms when certain microorganisms adhere to a surface in a moist environment and begin to reproduce.

Biofilm formation on surfaces usually starts with phototrophic organisms (algae, cyanobacteria) which use carbon dioxide (CO2) from the atmosphere and sunlight as their carbon and energy source.

Heterotrophic organisms (most bacteria and all fungi) need some organic source for their growth, and this is provided by the metabolites of phototrophic organisms or by airborne deposition.

The biofilm community is therefore sometimes formed by a single microbial species but in nature biofilms

almost always consist of mixtures of many species of bacteria, as well as fungi, algae, yeasts, protozoa, and other microorganisms, along with non-living debris and corrosion products.

All biofilm forming microorganisms may cause biodeterioration and degrade stone or render mechanically, chemically and aesthetically through the metabolic activities and biomineralization process in these biofilms.

The porosity of the surface, its mineral composition, alkalinity and its ability to retain air borne sea salts create an environment favourable to the settlement of microorganisms.

Studies on biofilms, along with their potential damage to a range of substrates, has led to investigations of a range of building substrates, coatings etc.

It is apparent that some species, in particular pigment-producing fungi (Alternaria, Penicillium, Aspergillus), can lead to deterioration of appearance which, even after removal of the species itself, can be difficult to remove.

Other species such as algae and lichens are also very brightly coloured and can rapidly develop and spoil the appearance of surfaces.

Black excretions from a filamentous fungi
Green algae
Red algae : One of the 5 common species of Trentepohlia

Red Algae

The genus Trentepohlia would not, at first glance, be taken as a green alga. Free-living species are mostly yellow to bright orange or red-brown in colour, due to the orange pigment, haematochrome (β-carotene), which usually hides the green of the chlorophyll. The genus is terrestrial and is often found in Europe on rocks, walls and tree bark. Where they are found on buildings, they can cause severe mechanical degradation and deterioration.

Fabio Rindi and Michael D. Guiry (2002) have identified five species of the genera Trentepohlia and Printzina in urban habitats in Western Ireland: Trentepohlia abietina (Flotow) Hansgirg, T.aurea (Linnaeus) Martius, T. iolithus (Linnaeus) Wallroth, (Kützing) Bornet, and Printzina lagenifera (Hildebrandt) Thompson et Wujek. These species formed perennial populations on a variety of substrata. Of the species identified, T.aurea and T.iolithus were found on old concrete and cement walls; in particular, the latter species formed characteristic, extensive, deep-red patches on many buildings.

Red Algae

Black Fungi

Chemoorganotrophic fungi are especially concentrated in stone crusts. They are able to penetrate into the rock material by hyphal growth and by biocorrosive activity, due to the excretion of organic acids or by the oxidation of mineral forming cations, preferably iron and manganese.

This can often leave a rust-like stain on paving slabs even after washing. The deterioration activities of dematiaceous fungi also include the discolouration of stone surfaces, due to the excretion of dark pigmented melanin.

Species capable of such staining are Alternaria, Aureobasidium, Cladosporium and Penicillium spp. The photographs below show a building wall covered with fungal growth (identified as Alternaria) sp.. The microscopic images show the development of fungal hyphae and on close-up, the pigmented spores can be seen.

Alternaria sp. on building wall
Alternaria sp.
Cladosporium sp.

Filamentous fungi are composed of many cells forming thread-like hyphae which form a mycelium, or network of hyphae. Most fungal species prefer to grow at acid to neutral pH (3-6) and only require 30% moisture to survive. From these dense mats, aerial reproductive hyphae (known as conidiophores) will release millions of spores into the space directly above and hence cause massive colonisation in suitable growing areas.

The most common contaminants on substrates such as roofs, pavements and walls are the pigment producing Aureobasidiumsp sp., and Cladosporium sp. and Alternaria sp.

These species will rapidly spread and colonise many surfaces causing disfigurement and decay by the release of pigments and acids respectively.

Indeed there are scientific studies that have identified over 22 fungal flora including filamentous micro fungi to be present on sandstone buildings. The major contaminant isolated was Aspergillus sp. which produced dark pigments and organic acids which were responsible for the decay of the sandstone historical monument.

Algae & Cyanobacteria

Phototrophic microorganisms (algae, cyanobacteria) can grow on stone surfaces or may penetrate the pore system of the stone itself. Phototrophic microorganisms have a direct effect on the deterioration of stone due to their pigments which cause an aesthetically detrimental effect.

Filamentous cyanobacteria (Nostoc sp, Leptolyngbia sp., Stigonema ocellatum) and green algae (Desmococcus olivaceus and Haemaotococcus pluvialis) are capable of forming dense mucous-like layers on surfaces which produce characteristic colourations on the substrata.

Nostoc. sp can produce blackish-green pigmentation which leaches into the substrate on which it is growing.


Botanically, mosses are non-vascular plants in the land plant division Bryophyta. They require sufficient moisture, access to nutrients and harvest sunlight to create food by photosynthesis. There are approximately 14,500 species of mosses. The most common species in urban Ireland are the greycushioned grimmia, Grimmia pulvinata; thickpoint grimmia, Schistidium crassipilum; and the wall screwmoss Tortula muralis.

Although mosses do not cause direct damage to roof tiles, they increase water capillary creep causing in the fullness of time corrosion of the fixings and ageing of the overall structure. They can cause some lifting when growing in the vertical bond. As they absorb moisture, they also add weight to roofs and when they become heavy enough or dislodged by bird activity etc, they can fall in gutters and down pipes and cause blockages.

On the ground the deleterious effects of mosses is slower to take effects, except on artificial grass, where they rapidly clog the drainage leading to runaway maintenance issues. It is recommended to clear moss before treatment. This is done by hand on roofs, or mechanical brushing on the ground, particularly on artificial grass. AlgoClear® Pro being de-activated in contact with biomass, it makes good sense to reduce it’s volume before applying the biocide.


Moss is part of the Bryophytes and, unlike plants have no vascular tissue and reproduce by the production of spores. They are prolifically produced by fungi, moss and, in particular, ferns. Most spores are distributed by the wind. Typically, spores are released in early May, for a period of about one week. Prior to release, the spore sacks are ripening, but once the conditions are appropriate, they release the spores and thereafter the spore sacks are empty.

Hence, the major period of concern for spreading is limited by the high sporulation period. Quaternary Ammonium Compounds (DDAC) are not effective at killing spores due to the spores having a thickened cell wall. However, as the spores begin to germinate, they produce protonema which are thread-like filaments which grow and colonise the substrate on which they have established.

The protonema has thin cell walls and it is at this stage that the DDAC is able to penetrate protonema and disrupt the cells, killing the organism prior to it becoming established on surfaces.

In addition to the effectiveness against moss, AlgoClear® Pro is an extremely effective algaecide and will be effective at reducing these species colonising most surfaces.


A lichen consists of 2 or more partners that live together symbiotically, with both of them benefiting from the alliance. One partner is a fungus. The other is either an alga – 90% of known lichen – commonly Trebouxia, then Trentepohlia or a cyanobacterium – about 8%, commonly Nostoc.

The alga or cyanobacterium is able to use sunlight to produce essential nutrients by photosynthesis that feed both partners. The fungus creates a body, called a thallus, in which they both live.

The fungus also produces chemical compounds that may act as a sunscreen to protect the photosynthetic partner.

There are more than 1,700 species of lichen in the British Isles. Approximately 30,000 species of lichen have been described and identified worldwide. The algal partners in lichens can be found living on their own in nature, as free-living species in their own right.

The fungal partners in British lichens are recognizable Ascomycetes or Basidiomycetes. However, they have come to need the right kind of algal partner in order to survive. Unlike other fungi or indeed their algal partner, they cannot survive on their own. Lichens have a variety of different growth forms. The simplest lichens are crusts of loosely mixed fungal hyphae and algae. Others are more complex, with leafy or shrubby forms like miniature trees, also having specialised structures to attach them to a surface.

It is not recommended to brush lichen before treatment. The AlgoClear® Pro solution being algaecide, the symbiotic relationship sustaining the organism is destroyed. The crust will become soggy in wet periods, desiccate in dry ones. Repeated cycles will detach the remaining crust from the substrate.