F 5.1

F 5.1


One-component low odour water-based floor lacquer. For wooden floors in heavy traffic residential areas and lighter traffic commercial floors.

Offers the ease of use of a one-component product with excellent levelling and flow characteristics. The product is ideal for use on previously sealed and untreated floors.

When lacquering an untreated floor or a floor sanded to bare wood, use one of Junckers' primers prior to the finishing top seal.

Strong has received the Danish Indoor Climate Labelling. A product with this labelling has undergone extensive volatile emission and odour tests. This ensures that there are no chemical substances in the product which adversely affect the air quality in the room.

For professional use only.


Product: Co-polymer polyurethane/acrylic lacquer.

Package sizes:
2½ litres: Matt and silk matt
5 litres: Ultramatt, matt and silk matt
10 litres: Matt and silk matt

Creamy/milky in the container. Colourless film when dry.


Coverage: 10 m² per litre.

Before application: Shake/stir well before use.

Application tools: Brush, roller, air/airless spray. Do not apply by pouring out the lacquer directly onto the floor.

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

Dilution: Delivered ready for use. Dilution is not recommended.

Drying time at 20 °C and 50 % RH: 
Approx. 4 hours.
Fully cured after 72 hours.
Apply only 2 coats of lacquer per day.

RH: Water-based products have a certain gluing effect and are therefore only recommended to be used in rooms with a stable humidity. This means that the difference between the highest and lowest relative humidity should not fluctuate more than 30 % over the year.

Cleaning of tools: Soap and water immediately after use.

Storage: Lasts for 1 year if unopened and stored at 20 °C. Not to be exposed to temperatures below 5 °C.


1 coat PreLak 8 m²/litre
+ 2 coats Strong 10 m²/litre.


Untreated/sanded floors:
Ensure that the surface is absolutely clean, dry and free from dust, wax, grease, polish, soap residues etc. Sand the surface to remove dirt and irregularities. Vacuum thoroughly and wipe off with a cloth well wrung in clean water.

  • Apply one coat of Junckers PreLak and leave to dry for a minimum of 2 hours.
  • Sand with sandpaper grit 150-180 along the fibres of the wood.
  • Vacuum sanding dust and wipe off with a cloth well wrung in clean water.
  • Apply one coat of Strong.
  • Leave to dry overnight and then apply the final coat.

Previously sealed floors:

  • Wash with Junckers SylvaNeutralizer.
  • Sand thoroughly using grit 150-180.
  • Vacuum sanding dust and wipe off with a cloth well wrung in clean water.
  • Apply one coat of Strong and leave to dry.
  • Before lacquering the full area, it is recommended to conduct a trial application on a smaller area.

How to conduct a trial application:
Lacquer a couple of spots, 2 coats at 4 hours interval. After drying for 24 hours check the spots for adhesion by scraping with the edge of a coin. If the adhesion is functioning and the appearance of the surface is acceptable, the floor can be lacquered. If the result is not acceptable, continue as described under “Wax/polish treated floors”.

Wax/polish treated floors:

  • Machine sand by first using 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”.


Before using the product, read the label on the container carefully and observe the recommended precautionary measures.

See Material Safety Data Sheet for detailed information. 


F 5.3 - Junckers PreLak
F 10.3 - Junckers SylvaNeutralizer