Taftflex 6221 is a one-component, moisture-curing polyurethane elastomeric adhesive sealant that forms a permanently elastic, paintable bond between substrates with different expansion rates.
PRODUCTS · POLYURETHANE SEALANT
Taftflex 6221
One-component polyurethane sealant and adhesive, permanently elastic and paintable.
Sibling products: Taftflex 6292
Industries: Automotive, Bus & Truck, Construction, DIY, Marine & Shipbuilding, Metal Fabrication
Polyurethane SealantMetalPlasticsGlassCompositesWood
Service temp
-40 to 80 °C
Cure speed
70 minutes (skin)
Headline properties from the Taftflex 6221 Technical Data Sheet. Refer to the current TDS for full specification.
Specifications last reviewed
Specifications
| SKU | 6221 |
|---|---|
| Chemistry | 1-component polyurethane (moisture-curing) |
| Appearance | Black, white, grey |
| Specific gravity | 1.15 |
| Fixture time | 70 minutes (skin) |
| Full cure | 3.5 mm/24 h cure rate |
| Service temperature | -40°C to 80°C |
| Shelf life | 12 months |
| Packaging | 310 mL cartridge, 600 mL sausage |
Substrate compatibility
- Metal
- Plastic
- Glass
- Composite
- Wood
- Fiberglass
Video
Technical Data Sheet
Download the current Technical Data Sheet for full specification, handling, and cure data. The complete TDS library cross-references every MightyLoc family by chemistry, substrate, and service window.
Compliance
RoHS statements and Safety Data Sheets for this product are available on request. Contact the MightyLoc team and we will send the current documents.
Panel bonding · 3 points
01 / 03
Continuous bead
Lay a continuous bead along the joint and tool it smooth with a putty knife and soapy water to seal it against water and weather.
02 / 03
Bond and seal in one
Lay the bead along the panel join so it both bonds the panel and seals the seam in one step. There is no separate gasket to fit, and the elastic bond stays flexible and paintable once cured, taking up movement.
03 / 03
Dissimilar materials
Joins dissimilar materials such as metal, composite and glass, where each moves at a different rate. The elastic bond flexes to absorb that movement and the difference in thermal expansion, so the seam stays sealed.
Tap a point on the image to see where and how to apply.
Application guidance last reviewed
Technical tools: Cure-time guide Service-temperature guide Substrate-pair selector
Frequently asked questions
Taftflex 6221 is a one-component, moisture-curing polyurethane elastomeric adhesive sealant used to bond and seal vehicle bodies, cab panels, body seams, welded joints, and lap seams on truck trailers, RVs, and metal roofs. After curing, Taftflex 6221 forms a permanently elastic bond between materials with different coefficients of expansion, including aluminium, steel, coated metals, wood, and concrete.
Taftflex 6221 forms a skin in about 70 minutes at 23 C and 50% relative humidity, then cures at a rate of roughly 3.5mm per 24 hours as it reacts with atmospheric moisture. Because Taftflex 6221 is moisture-cured, thicker beads and joints take proportionally longer to cure fully through the depth.
Taftflex 6221 has a permanent service temperature range of -40 C to +80 C once fully cured, which suits most automotive, transport, and outdoor sealing work. For application, Taftflex 6221 should be installed between 5 C and 35 C; do not apply it below 5 C, and in cold weather warm the cartridges to about 20 C first.
Yes, Taftflex 6221 is surface-paintable once cured and accepts water-based, oil-based, and rubber-based coatings. It is also non-staining and low odour, so Taftflex 6221 is well suited to finished panels and visible body seams. As coating chemistries vary, run a small compatibility test before painting a full production batch.
Taftflex 6221 cures to a flexible elastomer with 600% elongation at break and a Shore A hardness of about 40, giving it high recovery for dynamically moving joints. Its tear strength exceeds 10 N/mm, and the modulus at 100% extension is approximately 0.3 MPa, so Taftflex 6221 absorbs vibration and shock without cracking.
Taftflex 6221 has a 12-month shelf life when stored unopened in a cool, dry place between 15 C and 25 C, away from direct sunlight. Storing above 30 C can thicken the compound and make caulking difficult. Once a cartridge or sausage is opened, use Taftflex 6221 within 24 hours or the sealant can harden inside the pack.
Taftflex 6221 is supplied in a 310ml cartridge and a 600ml sausage pack, both applied with a manual or pneumatic caulking gun. It is available in black, white, and grey. After extruding Taftflex 6221 into the joint, smooth the bead with a putty knife wetted with soapy water before it skins over.
No, Taftflex 6221 is non-corrosive and bonds well to aluminium, steel, and coated metals, which is why it is used on body seams, rivet seams, and welded joints in transport equipment. For best adhesion, clean substrates so they are dry and free of oil and grease, and use a primer or activator where the substrate requires it.