Putty Knauf Fugen (Fugenfüller) - what is it used for

In this master class, we offer you to familiarize yourself with two possible options for puttying Knauf plasterboard joints according to European standards. Sealing gypsum board joints occurs much faster and with better quality when using Knauf Uniflot putty, since there is no need to use reinforcing tape.

Since January 2013, all Knauf enterprises have switched to producing plasterboard sheets with a semicircular thinned edge instead of the usual thinned edge. The new edge configuration increases the strength of the attachment area by 25 percent compared to a traditional thin edge. The seam becomes more resistant to cracking.

These methods are used for gypsum boards with a semicircular thinned edge; if you use gypsum boards with a regular, thinned edge, then use the method of sealing seams using reinforced tape!

What is Knauf-Fugen putty

The German company is known to a wide audience in many countries around the world. Most consumers pay attention to Knauf brand products when the need arises to repair their own home. This is a dry mixture made on a gypsum basis. However, it imposes certain restrictions on its use.

Plaster does not withstand constant contact with moisture. This is especially critical in the case of direct exposure to putty and water. In addition to gypsum, the building composition contains a number of additives, which can improve the quality of the product. Some components slow down the setting of the mixture, others retain water. It is worth noting that the gypsum solution itself hardens quickly. This problem is solved by including substances that prevent moisture evaporation. As a result, Fugen putty retains its viscosity for a long time.

Both gray and white compositions go on sale, but there are no differences in properties between them. The mixture is packaged in bags of 5, 10, 25 kilograms. In order not to lose the quality of the putty, it is necessary to add the required amount of water, as indicated in the instructions.

Various types of putty are also available for sale:

"Fugenfuller" (Knauf Fugen) - standard Knauf mixture.
Fugen GF is a composition intended for finishing works on plasterboard sheets (GKL).
Fugen Hydro is a moisture-resistant gypsum composition for processing gypsum fiber materials.

Note!
It is advisable to use each type of putty for its main purpose, based on the type of surface.

Knauf Fugen putty is intended for interior work.

Tools

Putty box for preparing putty solution
Metal spatula-trowel for mixing putty
Mixer for mixing the solution
Metal spatula (150 mm wide)
Wide metal spatula
Metal spatula for external and internal corners
A grater with a sanding mesh for sanding dry putty surfaces

GYPSUM DRY MIXTURES CAN BE IN DIFFERENT COLOR – FROM WHITE TO GRAY AND EVEN PINK. THIS IS EXPLAINED BY THE PRESENCE OF NATURAL IMPURITIES IN THE GYPSUM STONE. THE COLOR OF THE MIXTURE DOES NOT AFFECT ITS CHARACTERISTICS.

We thank the manufacturer knauf.ru for the information provided.

Technical and operational characteristics

The high demand for construction mixtures of the Knauf brand is due to no less high quality indicators. But before making the final choice in favor of one or another putty, it is necessary to study its properties. Despite the presence of several variations, they are all little different and are used in a similar scenario. Therefore, it is worth considering the technical characteristics of the conventional mixture, as it is more widely used:

The grain size is 0.15 mm - this fine-grained structure allows you to create an even finishing layer. The largest fraction can reach up to 0.2 mm.
The thickness of the laid coating is 1-5 mm. However, in most cases the layer rarely exceeds 3 mm. This creates an unnoticeable and strong base foundation.
To ensure long service life, the room temperature should be maintained at the recommended temperature. The minimum threshold below which you should not fall is +10 °C.
The drying time of the solution is 30 minutes. The exact interval depends on operating conditions, as well as the volume of the mixture mixed.
The shelf life of the building material is no more than 6 months, and therefore, before purchasing, you need to calculate in advance how much putty will be needed for finishing work. But subject to storage conditions.
Compressive strength is more than 2 MPa.
Bending strength – starting from 1 MPa.
Surface adhesion indicators – from 0.5 MPa.
1 kg of dry mixture is spent on preparing 1.3 liters of solution.

Thanks to the components of Fugen GF putty, a high-strength base is created, prepared for finishing. Fugen Hydro mixture can be used as a starting putty due to the fact that it is suitable for use in rooms where there is a constant high level of humidity. Fungi, mold and other pathogens do not develop on the finished coating.

Thanks to the plasticity of the mass, it is easy to work with

Advantages and disadvantages

Fugenfüller Knauf putty is valued primarily due to its advantages that are difficult to dispute. Among the obvious advantages it is worth highlighting:

The building compound is used when working with gypsum plasterboard, although the plasterboard surface is exposed to moisture.
Due to their high strength, concrete surfaces are effectively joined.
Environmentally friendly.
Putty is produced in different colors.
High adhesion, which is easily enhanced by additional primer treatment.
Putty is applied in a different thickness range - from the thinnest to a more reliable coating. But within acceptable limits.
The Knauf assortment contains a moisture-resistant option.
Thanks to its fine-grained structure, the putty completely fills small cracks.
Moderate consumption of putty contributes to economical spending on repair work.

Knauf offers three putty options to choose from, so it makes sense to consider the strengths of each individually.

Gypsum is a clean material that does not pollute the environment.

Fugenfüller or Knauf Fugen

The standard mixture for professional processing of joints of plasterboard panels does not crack after drying. For the manufacture of the composition, only environmentally friendly raw materials (gypsum) are used, and therefore there are no harmful emissions.

Knauf Fugen GF

Fugen GF mixture completely covers the entire surface of gypsum fiber sheets. The composition itself is durable and at the same time elastic. No cracks form on the treated and dried surface. The Fugen GF option is the same standard gypsum putty, but with the inclusion of polymer additives. There is no harmful effect on the human body.

Knauf Fugen GF – for continuous puttying of GVL

Knauf Fugen Hydro

This is a moisture-resistant gypsum option that is suitable for effective processing of gypsum board joints. It is also used when installing plasterboard slabs with tongue-and-groove fastening. When dry, the putty shrinks minimally and does not crack. Due to the content of environmentally friendly polymer and hydrophobic components, the mixture is resistant to moisture.

Knauf Fugen Hydro - moisture-resistant gypsum putty for treating joints

List of disadvantages

Even such a professional mixture has a number of disadvantages that must be taken into account first. This allows you to choose the only correct solution in each specific case.

One of the significant disadvantages is the high drying speed, which imposes certain inconveniences. In particular, you need to act extremely quickly and dilute small portions of the solution. With a large scale of work, this takes a lot of time. Other disadvantages:

It is not recommended to use the material for large surface bends. When the level difference is 3 mm or more.
Hardened gypsum coating is difficult to sand because it is very durable. At this stage, the worker requires endurance and considerable effort.
If thin and light wallpaper is chosen for finishing, dark gaps may appear.
The inconvenience lies in the maximum thickness of the applied layer - no more than 3 mm.

The main disadvantage is that it dries quickly in the mixing container.

List of mixtures

The Knauf brand offers mixtures for drywall joints:

KNAUF-Fugenfüller,
KNAUF-Fugenfüller Hydro,
KNAUF-Fugenfüller GF,
KNAUF-Uniflot.

There is no need to buy the first building material you come across from the list; each of them has its own characteristics and is used in a certain segment of work. Solutions differ in:

Areas of use,
Costs,
Factory packaging,
Technical characteristics (viscosity, moisture resistance, consumption, setting time, etc.).

Area of use of putty

A standard gypsum-based putty composition is used for interior work. Despite this, the list of tasks is far from small:

Sealing the seams of concrete floors.
Professional processing of gypsum board joints (regardless of the type of edges).
Restoration of coatings made of various materials - gypsum plasterboard, concrete, tongue-and-groove blocks.
Treatment of the entire surface of walls and partitions
For reinforcement - during fastening of mesh or special corners.
As an adhesive for fastening plasterboard sheets to a leveled vertical surface.
Creating a base coat for wallpapering.
Filling recesses at installation points of fasteners (masking screw heads).

Attention!
Compliance with the technology of applying the material allows you to avoid many undesirable consequences. In this case, the putty does not crack, and the shrinkage rates are so minimal that it is invisible to the naked eye.

The putty composition can be used for various purposes without the risk of loss of properties

Conditions and procedure for performing work

Before starting work using Knauf-Fügen putty, care must be taken to create suitable conditions. Any master needs to know this, especially beginners. The optimal temperature ranges from +10 °C to +30 °C.

Processing of plasterboard sheets should only begin after all “wet” processes have been completed, which lead to changes in temperature and humidity levels in the premises. This includes installation of self-leveling floors, plastering of walls and ceilings, installation and dismantling of windows (especially from autumn to winter).

You need to start putting putty when the surface to be treated is completely dry. Otherwise, linear deformation of the gypsum board and, as a consequence, cracking of the coating cannot be avoided.

It is also prohibited to add other components to the solution, otherwise the quality of the putty will decrease, and significantly! The manufacturer produces putties with a specially selected composition. It is undesirable to use a thickened mixture, as well as dilute it with water - this will not return the original properties.

Preparing the surface for puttying

Preliminary surface preparation is strictly necessary and neglecting this stage is highly discouraged. The first thing you need to do is get rid of the old finish - wallpaper, plaster. The base is thoroughly cleaned of other contaminants - mold (if any), grease deposits, dirt, dust. After cleaning, it is necessary to treat with a primer depending on the type of walls.

Processing the rough coating is a mandatory stage of the work.

Plasterboard structures

The frame is assembled according to technology, which avoids sagging of plasterboard sheets when creating ceilings or deformations of cladding and partitions. The sheets must be firmly fixed to the frame, in which the pitch of the fasteners plays an important role:

170 mm – ceilings;
250 mm – partitions.

The sheets themselves must be laid out in a staggered manner. The displacement of seams also has its own weight:

400 mm relative to vertical;
150 mm relative to horizontal.

The screw caps are covered with putty (Knauf-fugen). The end parts of the sheets should be cut at an angle of 22.5°, which is effectively achieved with a special tool (edge plane). Also, the ends must be primed with a deep penetration compound.

At the end of the preparatory stage, a primer is applied to the surface. You can use a brush, roller, spray. Wait until it dries - each type of primer has its own duration:

Tiefengrund – 3 hours;
Betocontact – 12 hours.

It is important to ensure that the treated surface does not become dusty again.

Seams and small recesses between sheets are coated with the composition using a spatula

Dilution of putty

Most beginners make a number of mistakes while still at the stage of preparing the mixture for surface treatment. Do not allow air to get in when mixing the mixture. For this reason, it is not advisable to use mixers or other mechanical devices. It is better to dilute portions manually. At the very least, the mixer speed should not exceed 300 - then air will not penetrate into the mixture during the mixing stage.

The kneading procedure has a number of features:

On average, 0.8 liters of water are taken per kilogram of dry mixture. The exact proportions are indicated on the label for each Knauf product.
The dry composition is carefully and gradually poured into a container of water for proper impregnation.
When the mixture is poured, wait 2-3 minutes. This time is enough for the mixture to become saturated with water. Only then start stirring. If you start right away, you will not be able to achieve a uniform structure, and the putty will lose its technical characteristics.
The temperature of the water for mixing the dry mixture plays an important role. Indicators should be kept within +5 °C to +30 °C. Due to warmer water, the moisture resistance of the mixture deteriorates and subsequently the coating will begin to crack after drying.
It is advisable to mix the mixture manually with a spatula. Using a mixer at low speeds is important when you need to prepare a lot of solution - it is very difficult to knead such a volume with your hands (even with a shovel).
The ready-to-use mixture should have a uniform, creamy consistency. Initially, the solution seems liquid during mixing, but you cannot deviate from the proportions and add more dry mixture. After some time, the consistency will come to the desired form.

Attention!
You should not throw the remaining putty back into the container with the prepared mixture. This shortens the lifespan of the composition, which quickly renders it unusable.

The rate of consumption is affected by the type of finishing work

Instructions for use

To obtain high-quality coverage and avoid erroneous actions, you should strictly follow the instructions. In particular, start work when the surface is cleaned and dried. You should also not allow dirt or foreign bodies to get into the putty. Tools must also be clean.

There are several ways to use the Knauf-Fügen dry mixture:

continuous surface coating;
installation of KNAUF-gypsum board partitions;
processing of joints of gypsum board sheets.

Each case has its own characteristics that should be taken into account. Otherwise the work will have to be redone.

Complete puttying of concrete surfaces

The solid technique is used in case of minor unevenness. Buying expensive putties is not practical from an economic point of view. A day before the start of work, the surface is primed.

The putty is applied to the walls using a spatula or trowel. Any technique is used that is convenient. For example, cross-shaped - first follow vertical stripes, then change direction to horizontal movements for leveling. Or perform fan-shaped manipulations.

The thicker the layer, the more liquid the plaster should be.

Installation of KNAUF gypsum boards

Putty is convenient when attaching plasterboard. During installation, the solution is applied to the recesses of the slabs:

bottom row groove;
vertical groove from the end part.

Next, the gypsum board is pressed tightly, and the remaining remaining mixture is removed. The process is reminiscent of laying bricks using cement mortar. When the installation of the slabs is completed, the seams are sealed with fugagypsum putty.

Sealing joints of plasterboard sheets

Processing of gypsum board seams is carried out in several approaches. The Uniflot composition was developed specifically for these zones. The sequence of actions varies depending on the type of edge. It can be straight or folded. Processing joints of gypsum board sheets with a straight edge:

The seams are filled with putty to the full depth, maintaining uniformity.
Wait until the mixture dries, then clean the surface of the closed joints.
Cover the sheets with a leveling layer of putty mixture.

Adjacent gypsum board sheets relative to a straight edge are mounted with a gap of 5 to 7 mm. Sequence of actions in the case of a folded edge:

To begin, apply the first layer of putty.
A special reinforcing tape or fine mesh is applied and pressed into the putty mixture with a spatula to avoid the appearance of wrinkles and bubbles.
A second leveling layer is applied to the dried surface.
When the putty dries, the joints are sanded.

Note!
It is convenient to carry out the work with a 150 mm wide spatula. Moreover, it is advisable to choose a tool that has a handle in the form of a screwdriver tip, in order to tighten protruding screws at the same time.

Plastering is a simple operation that requires only time and patience

Surface preparation

Knauf sheets and Knauf supersheets must be firmly fixed to the supporting base (frame). When puttingtying any GVL joints, the edges of the sheets must be pre-treated with KNAUF-Tiefengrund primer. The end and cut edges of gypsum boards with a chamfer removed are also treated with KNAUF-Tiefengrund primer before puttying. When puttingtying gypsum board joints formed by longitudinal unedged edges, clean the surface of the joints from dust without moistening. Do not prime the longitudinal edges. When completely puttying, clean the surface from dirt, dust, exfoliation and remove any form lubricant residues from the concrete. Treat the surfaces of plasterboard and gypsum fiber sheets, gypsum and cement plasters with KNAUF-Tiefengrund primer. Treat concrete and smooth surfaces with low absorbency with KNAUF-Betokontakt primer to improve adhesion (adhesion). Primers are applied by brush, roller or spray. After application, allow the primer to dry: KNAUF-Tiefengrund (3 hours), KNAUF-Betokontakt (12 hours). Avoid dusting the primed surface.

Consumption

How much putty is required depends on the type of work. The type of surface being treated also plays a role in this. When sealing plasterboard joints, the consumption per 1 m2 of surface will be 250 grams. In the case of continuous application of putty - from 800 g to 1 kg per square area with a layer thickness of no more than 1 mm.

If you need to cover an already plastered surface, then the putty consumption will be slightly higher (0.8-1.2 kg per square area), depending on the degree of roughness of the rough coating. As for the installation of tongue-and-groove slabs, you should take into account the figure of 1.5 kg per 1 m2.

Reviews

Choosing a manufacturer who specializes in producing high-quality building mixtures is the key to successful finishing. Most professional finishers prefer the Figenfluger Knauf mixture. There is also no doubt about the durability of the company’s materials.

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How to seal gypsum board joints

All mixtures from the Knauf line are diluted in a plastic container into which water is poured, then the dry composition is poured. The putty is kneaded to a thick consistency manually or mechanically (mixer attachment on a drill).

Here are the master's recommendations for work:

Use a metal tool (spatula)
Fill the joints using vertical movements from bottom to top,
If you are gluing tape, first fill the seam with the solution, then attach the AL,
Mix the solution as little as possible, especially for the Uniflot brand,
Before work, clean the gypsum board seams from dust,
After use, wash the tool.

In conclusion, we add that Knauf mixtures are stored in a dry place and in unopened packaging. It is optimal to buy the material before work; if moisture gets into the dry composition, you will have to throw it away - it will set immediately after mixing.