International Interline 921

Part A: UN3082 (Class: 9, Pk Grp: III), Part B: UN3470 (Class 8, Pk Grp: II)
For the treatment of weld seams, lap joints & kerb angles.
Available in 18 Litres
£683.42 £569.52
In stock
Product Description

International Interline 921 is a two component, solvent free, chemically resistant epoxy phenolic caulking compound formulated to provide ease of application, and greater flexibility in scheduling of tank lining applications.

Best Uses

International Interline 921 is a versatile caulking compound suitable for application by standard airless spray equipment in both new construction solutions, and for refurbishment of corroded tanks. The extended recoat window afforded by Interline 921 allows increased flexibility in working practice, and improved scheduling of contracts to allow more rapid return to service.

Interline 921 caulking compound should be used for the treatment of weld seams, lap joints, kerb angles and other surface irregularities to provide a smooth uniform transition between uneven surfaces, prior to the application of Interline glass reinforced laminate systems.


All surfaces to be coated should be clean, dry and free from contamination. Prior to paint application all surfaces should be assessed and treated with ISO 8504:2000.

Oil or grease should be removed in accordance with SSPC-SP1 solvent cleaning.

Abrasive Blast Cleaning

This product must only be applied to surfaces prepared by abrasive blast cleaning to SA21/2 (ISO 8501 - 1:20017) or SSPC SP10. A sharp, angular surface profile of 75-100 microns is recommended.

Interline 921 must be applied before oxidation of the steel occurs. If oxidation does occur the entire oxidised area should be reblasted to the standard specified above.

Surface defects revealed by the blast cleaning process should be ground, filled or treated in the appropriate manner.

Where local VOC regulations allow, surfaces may be primed with Interline 982 to 15-25 microns (0.6-1.0 mils) dry film thickness before oxidation occurs. Alternatively, the blast standard can be maintained by use of dehumidification.

Interline 982 can hold a blast for up to 28 days in the semi-protected environment of a tank interior. If moisture is present on the surface, oxidation will occur and reblasting will be required.

Technical Details


Interline 921 can be applied directly to correctly prepared bare steel. However it is suitable for application over the following primer:

Interline 921 is normally topcoated with itself or Interline 984. For other primers/topcoats, please consult our Technical Team.

Consult the Promain Technical Team to confirm that Interline 921 is suitable for contact with the product to be stored.

Technical Info

Components: Two Components
Type: Solvent Free
Finish: N/a
Stock Colours: Green
Tintable: No
VOC Content: 90 g/lt
Volume Solids: 100%
Suitable Substrates: Weld Seams, Lap Joints, Kerb Angles
Application Method: Airless Spray
Theoretical Coverage: 0.50 m2/litre at 2000 microns d.f.t. and stated volume solids
Wet Film Thickness (WFT): 1000-4000 microns (40-160 mils)
Dry Film Thickness (DFT): 1000-4000 microns (40-160 mils)
Induction Time: -
Pot Life: 50 minutes at 15°C
Touch Dry: 9 hours at 15°C
Overcoatable: After 20 hours minimum to 28 days maximum at 15°C
Hard Dry: 20 hours at 15°C
Cleaner / Thinner: DO NOT THIN , Clean tools with either International GTA853 or International GTA415
Shelf Life: 18 months minimum at 25°C. Subject to re-inspection thereafter.
Packaging: Available in 18 Litres

The manufacturers data sheets are available for download from this website. It is your responsibility to read and understand all aspects of the data sheets before you place an order and prior to application. Please pay special attention to the preparation, mixing and application temperatures of the product, cleaning of substrate and environmental factors such as temperature, rain etc. Quoted coverage rates are based on the manufacturers theoretical rates and may vary depending upon substrates absorption, texture and application. We always recommend a test is carried out to ensure suitability.

Customer further agrees that Promain have no liability for any errors or omissions contained within the Product Data Sheets and are not liable for failure due to misapplication or inadequate substrate cleaning and preparation. For more information please refer to our Terms & Conditions.

Recommended products to use