Verified by manufacturer 5 months ago
ISO 9001 Quality Management
Certificate type
A highly elastic polyurethane joint sealant. Single component, easy to use and UV stable.
Designed for civil and industrial movement, expansion, control and dilatation joints in both architectural and heavy construction.
Contact the manufacturer's technical team for more information or for specification support.
Koster PU-Flex 25 is a highly elastic, low modulus polyurethane sealant, with good UV resistance and excellent adhesion to typical construction materials. Koster PU-Flex 25 is one component and cures with moisture to form a flexible sealant which can be overpainted after curing is finished.
Features and benefits:
Designed for civil and industrial movement, expansion, control and dilatation joints in both architectural and heavy construction. This versatile material can be used to seal many types of substrates including:
Porous substrates (no primer required):
Non-porous substrates (Koster PU Primer 120 required):
Preparation and priming:
Ensure that the air and substrate temperatures are +5°C or higher and that all surfaces are clean, dry and free from dust and grease. Clean, porous, absorbent substrates require no primer. Use Koster PU Primer 120 for nonporous (non-absorbing) surfaces.
Insert a closed-cell foam backing rod into the joint. this backing rod should be compressible and tight fitting. Depth for insertion will depend on the joint width (see below for ratio advice).
Application:
Koster PU-Flex 25 is installed with the Koster Special Caulking Gun (without attachments). Joint widths up to 10 mm are filled in the width / height ratio 1:1, from 10 to 30 mm with a ratio of 2:1. For critical substrates or unknown materials it is recommended to carry out adhesive pull-off tests prior to installation. If the substrate has a layer which may not be removed (eg coatings), adhesion and compatibility tests must be carried out in advance.
Hand pump the material into the joint - against the backing rod - until it is flush with the wall surface. Finally smooth the uncured material.
Materials:
For further information or design assistance, please contact Technical@kosteruk.com and we will be happy to assist.
Color | Grey |
Finish | Matt |
Material | Polyurethane (PUR) |
Shape | Formless |
Length | Bespoke |
Width | Bespoke |
Height | Bespoke |
Warranty description | Ten year |
Uniclass | |
CAWS | M21/85 Sealant joints Q21/650 Cold joint sealing P31/710 Sealing P31/40 Sealing around services M12/65 Sealant movement joints M40/75 Sealant movement joints M21/530 Sealant joints Q21/650 Cold joint sealing M40/815 Sealant movement joints H13/740 Sealant joints L20/820 Sealant joints L10/75 Sealant joints L20/80 Sealant joints M12/430 Sealant movement joints L10/810 Sealant joints E40/530 Sealant |
Product range |
Standard | To BS EN ISO 11600. |
Material | One-part polyurethane. |
Class | F-25LM. |
Colour | Grey RAL 7040. |
Bonding primer | Koster PU Primer. Guidance for specification option: For non-porous surfaces. No primer. Guidance for specification option: For clean, porous and dry surfaces. |
Cleaning | Clean tools using Koster PUR Cleaner after use. |
Package | 600 mL foil cartridge. |
Curing Time: | 2 mm after 24 hours (at 25°C and 50%). |
Skin formation at 23°C and 50% Relative Humidity (RH) | Three hours. |
Joint width | Maximum of 30 mm. |
Elongation at break | >600%. |
Viscosity | Non sag. |
Temperature resistance | -30°C to + 80°C. |
Joint movement | ±35%. |
Shrinkage | 5%. |
Elastic recovery | Recovery from deformation 90%. |
E modulus | 0.22 MPa. |
Shore hardness - A | Approximately 25. |
Density / Specific gravity | Approximately 1.32 g/cm³. |
Contains Red List materials | No |
Country of material origin | Germany |
Country of product manufacture | Germany |
Recyclability | Packaging is easily and fully recyclable. Manufacturer guidancePackaging is easily and fully recyclable. |
Recycled contentAs defined in clause 7.8 of BS EN ISO 14021 | 0 % |