Mixed incorrectly could lead to the need for rework, additional costs or even the formation of structural damage. Mixing done right – a “how to” guide from Festool
Efficient and reliable mixing is the ideal basis for processing plaster and filler
The importance of correctly mixing materials in powder form is often underestimated. Philipp Stahl, master painter and application engineer at Festool, describes why this process in particular is so crucial. The combination of stirrer and stirring rod also plays an important role in mixing and stirring and needs to be tailored to the relevant material on a case-by-case basis.
Painters encounter a multitude of different materials in their everyday working life: Various types of plaster, filler, paint, wallpaper paste, clear coat, reinforcement adhesive, varnish and two-component coating systems. As a rule, these materials each require a different choice of stirring rod. In everyday work, painters often use the same stirring rod for different materials. The result is that the materials are often mixed incorrectly. This could lead to the need for rework, additional costs or even the formation of structural damage. What is particularly aggravating is that the material manufacturer’s warranty could also be rendered void due to incorrect application. For the painter, this usually ends in substantial follow-up costs and potential compensation demands from the end customer. This risk can be easily avoided by simply using the correct stirrer, stirring rod and settings in accordance with material manufacturer specifications.
Of paramount importance: Surface preparation
In demanding work processes – such as laying floor coatings using epoxy resin or PUR – the material is made up of two components. During mixing, it is especially important to ensure that the quantities and proportion of components A and B are carefully and accurately balanced, that the timings specified by the manufacturer are kept to and that the components are mixed properly. If this is not the case, damaged areas may form on the coating and adhesion issues with the underlying surface may crop up. During mixing, it is recommended to peruse the component manufacturer specifications on the designated data sheets and to keep exactly to the specified quantity proportions and mixing speed. “If the components are mixed at too high a speed, the mixture heats up faster. This means the material sets too quickly, impairing adhesion with the underlying surface and reducing the processing time,” explains master painter Stahl. He continues: “When using liquid resins, we recommend a so-called disc stirrer which ensures that the two components are mixed in the ideal way.”
Self-levelling filler for the floor
Painters are increasingly using self-levelling filler when it comes to flooring in order to create an even underlying surface for the decorative floor coverings, laminate or prefabricated parquet which are to be added later. Mixing self-levelling filler incorrectly could make it form lumps. This results in a residue of dry material – usually at the bottom of the bucket. Using a classic stirring rod that is spiralled to the right could also introduce an excessive amount of air into the material. This would result in the material not mixing into a homogeneous mass, even after long periods of stirring. This leads to damaged areas with some material remaining in powder form or air bubbles on the surface – these appear when too much air has been introduced to the mixture. “For this reason, it is recommended to use a suitable stirring rod and to ensure that the speed and stirring duration remain in accordance with manufacturer specifications. For this particular job, we recommend using the whisk as its special design lets hardly any air into the material and reliably forms a homogeneous mixture,” says Stahl.
Firm filler and plaster for walls
“In order to mix viscous reinforcement materials and plaster, we recommend using a stirring rod that is spiralled to the right and which mixes the material from the bottom to the top. This ensures that all the material is mixed evenly,” describes Stahl. In order to agitate clear coats, dispersion adhesives, wallpaper paste or thin materials, the application engineer recommends using a stirring rod that is spiralled to the left and mixes the material from top to bottom.
It’s all down to the perfect stirrer
For the vast majority of mixing materials, both in liquid and solid form, Festool recommends a stirrer with at least 1200 W and two-gear transmission with variable speed settings for mixing lightweight and medium materials. “In addition, thanks to the patented ErgoFix height adjustment feature, our stirrers can be individually adapted to the height of the operator. This makes a natural, upright and effortless working position possible. At the same time, the ErgoFix adapter, with its classic M14 tool reception, makes it possible to quickly change stirring rods (FastFix function) without the need for tools,” Stahl adds.
Heavy, compact materials should be stirred in first gear since the high torque means that the maximum stirring force is readily available. Meanwhile, liquid materials should be stirred in second gear at the appropriate speed (see manufacturer specifications). If the wattage of the available stirrer is too low, it requires a lot more effort to mix the material perfectly since the missing power often has to be compensated for with physical input.
Correct mixing enables painters to achieve the desired working result as well as avoid unnecessary hassle and the consequent expensive rework.
Philipp Stahl (master painter and application engineer at Festool Germany)
Before acquiring a professional mixing system, think about what requirements you encounter in your work and which materials you generally need to mix
Match the suitable stirring rod to each application/material
Observe manufacturer specifications
Adapt the speed as required and keep to specified mixing times
Product list: recommendations from Festool
MX 1000/2 stirrer
Stirring rod: HS 2 R with ring (for mixing firm filler and plaster)
Stirring rod: HS 3 R with ring (for mixing plaster, screed, filler and adhesive mortars)
Stirring rod: HS 3 L with ring (for mixing thin materials such as paint and varnish)
Stirring rod: WS disc stirrer (for mixing paint and liquid epoxy resin)
Stirring rod: CS whisk (for mixing self-levelling filler)
For more information about the unique Festool products contact Vermont Sales on 0113147711 or visit their web site www.vermontsales.co.za Festool is available from leading specialist outlets country wide for information on your nearest outlet call Vermont Sales, or go to www.festool.co.za and click on dealers
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