Render Care is a range of products formulated for the maintenance of buildings external envelope and surrounding amenities. At the core of the range, AlgoClear Pro carries out the essential work of eradicating live contaminants. Other specific marks are identified and treated using the appropriate formulation.
The first step successfully cleaning render is determining the type of contamination present at the surface and below. Some contaminants are easily treated with a simple spray (algae) whilst some others will require brushing with the biocide if of biological origin, or a with an appropriate gel: This will apply to stains of fatty origin, wood tannin, metallic oxide run off etc.
Surface characteristics are also important to the procedure. Smooth or deeply textured, porous or non porous, hard or soft. The aggregate cohesion of a render can vary from hard wearing to powdery. The ratio of ingredients and use of plasticisers at the time of application are a probable cause. If left for an extended period under a thick biofilm, the surface is will eventually soften to the point of marking under a low pressure jet.
Self cleansing is important to the process. It is based on the concept that once dead a biofilm sheds itself. On a roof the rain washes the discolouration within a few weeks. Lichen and other symbiotic life forms breakdown with diurnal cycles and fall. The process is substantially complete within a few months.
On a wall, the amount of rainwater is not always sufficient to have the full cleansing observed on a roof. When the contaminant is an algae, there is enough driving rain for the job but not always with fungi and their dark signature. If left on the surface after the AlgoClear Pro decontamination grey marks will breakdown into a fine powder and dissipate over a period up to 18 months. Alternatively, brushing with MetaClear will complete the cleaning cycle in a single visit.
AlgoClear Pro and MetaClear are sometimes used in conjunction with other techniques. They all have advantages and limitations. Steam at supercritical temperatures is useful to remove a first layer of grime, but can degrade acrylic resins with a melting point only slightly higher than that of the steam.
High pressure is not generally a good idea. If the render is laid over an insulating layer, a local pressure can generate cracks and loss of small debris. This has also been observed on boundary walls with no insulation.
Attractive for it’s simplicity, brushing will affect soft or low cohesion renders and should be done evenly. If an area where a long vertical streak of black is present (Window cills, coping stone joints) localised brushing can smooth the surface slightly giving the impression of a discolouration under some light conditions.
If uncertain, the use of MetaClear will lessen the risk. The soft brush used in the application of the gel is lubricated by the gel and does not abrade the surface. The discolouration is chemically removed rather than mechanically.
Safety: Broadly safety will focus on access, and factors arising as a result of using chemicals. For the operator: Gloves and face protection are required, and the use of appropriate brass connectors for the circuitry. In dense urban environments the biocide is applied with a low pressure bar alleviating all risk of splash back or spray drift.
Ground protection: Spray droplets will leave a local burn mark on foliage. Protection of delicate plants is best provided by means of a light geotextile fleece covering. If accidental spray reaches an unprotected area, clear water sprinkling will prevent damage. The active ingredient is not systemic.
Domestic animals: Incidents are very infrequent, but a concern to the pet owner. The product is used in low concentrations, but ponding and subsequent drying or partial drying of the pond will result in a temporary concentration conceivably bringing a risk to domestic animals.
Access should be restricted until the ground is dry and, if ponding has taken place, rinsed.
The appropriate technique allows a complete decontamination of a building. This consists in spraying fast and coarse droplets onto the surface until saturation. Pressure and flow are important to ensure delivery in windy conditions. The product is left to dwell beneath the surface, where it will provide protection and finish the decontamination process.
When AlgoClear Pro is brush applied, the foam resulting from brushing a biofilm is often reddish brown or yellow. When this is the case it needs rinsing by mean of a final biocidal spray before drying.
The MetaClear and OxiClear are gels formulated specifically for cleaning render and masonry. The viscosity prevents capillary ingress into the substrate. This is particularly important when the active ingredient needs to be kept out: Sodium hypochlorite and acids in particular.
A gel does not evaporate. As a result it does not release fumes. This is as important to the building occupiers and neighbours as it is to the operator who would otherwise inhale them for prolonged periods, whether their smell is masked or not.
The concentration of a gel remains constant throughout the cleaning process. This cannot be maintained when a water soluble oxidising agent is used (sodium hypochlorite). As the water evaporates, the surface concentration increases with the associated risk of damage. Controlling the process using oxidising agents is critical to delivering quality.
Churning and dwell time
Gels do not penetrate by capillary action. It will only dissolve the first layer a few microns deep. To dissolve the full layer of metabolites, one needs to agitate the gel with a brush to renew the active interface. Dwell time has some short effects, but , and not has much as churning the gel.
Time to re-spray. There is no standard answer to the latency one can expect from the AlgoClear treatment. Broadly, the time it took an elevation to collect grime will be the same with the addition of a clean period corresponding to time AlgoClear Pro dwells in the render, which would be about two years.
If the elevation is receiving regular driving rain, a decennial application of HydroClear will lower the moisture level in the wall and help maintain it in good condition. The biofilm is likely to return more slowly.
When the main cause of a render disfiguration is an inappropriate design detail or dysfunctional component, it is sensible to address it. Insufficient overhangs on copings and sills are common and easily rectified.
