F 5.5

F 5.5


A water-based acrylic filler for filling gaps. Mixed with sanding dust from the sanded floor, it is used for filling small gaps in floors.

PreFill is quick drying and can to be used in combination with Junckers water-based priming and floor-finishing products.

PreFill is the ultimate water-based solution for floors made of wood species sensitive to changes in humidity.

For professional use only.


Product: Water-based acrylic filler.

Package sizes: 5 litre.

Appearance: Creamy/milky. When mixed with sanding dust from the sanding, the mixture dries up to the same colour as the wood.


Coverage: Approx. 5 - 20 m² per litre depending on the condition and the type of floor, e.g. Industrial Parquet: 6 - 8 m² per litre.

Before application: Shake/stir well before use.

Application tools: Broad full-edged spatula of stainless steel.

Substrate temperature: Minimum 15 °C and maximum 25 °C.

Dilution: Mix into sanding dust. Add Junckers PreFill to adjust the viscosity. Dilution with water is not recommended.

Drying time at 20 °C and 50 % RH :
45-90 minutes depending on film thickness.

Cleaning of tools: Soap and water immediately after use

Storage: Lasts 4 years if unopened and stored at 20 °C. Not to be exposed to temperatures below 5 °C.


High traffic areas:
PreFill mixed with sanding dust
+ 1 coat PreLak 8 m²/litre
+ 2 coats Strong 10 m²/litre or HP Commercial 10 m²/litre

Low traffic areas:
PreFill mixed with sanding dust
+ 1 coat PreLak 8 m²/litre
+ 2 coats ProFinish 10 m²/litre 


Untreated/sanded floors:
The floor surface should be clean, dry and free from dust, wax, grease, polish etc. Machine sand the surface to remove dirt and irregularities using sandpaper grit 120-150.

  • Mix enough PreFill into sanding dust until a thick but spreadable past is obtained. If too thick adjust with PreFill.
  • Spread the paste quickly using a stainless steel spatula. Let dry.
  • Sand with sandpaper grit 120-150 to remove dried filler from the wood surface. Vacuum thoroughly.
  • Proceed according to one of Junckers “System recommendations”.

Previously sealed floors:

  • Machine sand by first using sandpaper grit 24-36 to strip old coats.
  • Then remove abrasion marks using grit 60-80.
  • Finally, use grit 120-150 to obtain a completely smooth surface. Vacuum thoroughly.
  • Treat the floor as described under “Untreated/sanded floors”.


F 4.2 - Junckers ProFinish
F 5.1 - Junckers Strong
F 5.3 - Junckers PreLak
F 8.5 - Junckers HP Commercial