3M
3M 8369 White Heavy‑Body Seam Sealer 310 mL Flex‑Pack – 5‑10 min Work, 24 hr Cure
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Hazardous material · Paste
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Ground freight only (UPS/FedEx). Cannot ship via Air, USPS, or to PO boxes. APO/FPO addresses excluded.
WARNING: Cancer & Reproductive Harm
This product can expose you to chemicals known to the State of California to cause cancer and reproductive harm.Tap for details → P65Warnings.ca.gov
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Overview
Built for the job.
3M™ MSP seam sealer is a high quality, heavy-bodied, general purpose, moisture-curing seam sealer for interior and exterior body joints. Our sealer adheres well to properly prepared primer, paint, and bare metal surfaces.
3M 08369 Seam Sealer is a 310 mL Flex-Pack white paste designed for sealing panel seams and filler joints before final coating. It provides a smooth, paint-ready surface on bare metal, OEM finishes, or existing primer layers.
The formulation opens to work within 5-10 minutes and reaches full cure in 24 hours, allowing rapid progression through the repair cycle. It can be applied at temperatures from 30°F to 200°F (-34°C to 93°C) and offers consistent coverage across compatible substrates, reducing flash time before topcoat application.
Use with appropriate personal protective equipment: gloves, protective clothing, and a respirator are required due to acute toxicity, aspiration hazard, and carcinogenic properties. Apply in well-ventilated areas and follow first-aid procedures for inhalation, skin, eye, or ingestion exposure.
Why Pros Choose 3M MMM
- Seam sealer works for both interior and exterior auto body joints
- One-part formula is ready to use without any mixing
- Strong adhesion bonds to many surfaces
- Tack free in 30 minutes and is immediately paintable
- Recommended for use with 3M™ flexible package applicator gun, 08398 (sold separately)
- A single component moisture-curing MSP seam sealer
- Designed for interior and exterior body joints
- Adheres well to primed surfaces except acrylic lacquer
- Paintable immediately
- Immediately paintable up to 72 hr
How to Use
For use on bare metal, door hem flanges, boor jambs, door skins, exterior seams and joints, floor pans, galvanized, general purpose, interior seams and joints, joint filling, rear body panels and rocker panels
- Clean the substrate (bare metal, OEM, or primer) to remove dust, oil, and loose material; ensure it is dry.
- Apply the seam sealer uniformly with a brush, roller, or spray gun at an ambient temperature between 30°F and 200°F (-34°C to 93°C).
- Allow the first coat to flash for 5-10 minutes before handling.
- If additional coverage is required, apply a second coat after the flash time.
- Let the applied seam sealer cure for at least 24 hours before sanding or overcoating.
Compatibility
Compatible substrates: Bare Metal, Primed Surface.
Compatible paint systems: Lacquer, Acrylic.
Specifications
| Part No. | 8369 |
|---|---|
| Product Line | MMM |
| MFR Model | 08369 |
| Standard/Approvals | OSHA 29 CFR 1910.1200 |
| Application | For use on bare metal, door hem flanges, boor jambs, door skins, exterior seams and joints, floor pans, galvanized, general purpose, interior seams and joints, joint filling, rear body panels and rocker panels |
| Manufacturer | 3M Products |
| Alternate Part Number-1 | 60455050132 |
| UPC | 051135083697 |
| Brand | 3M™ |
| Maximum Sale Quantity | 6 |
| Maximum Sale Day | 7 |
| Applicable Materials | Bare Metal |
| Composition | 15 to 40% Limestone, 10 to 30% Calcium Carbonate, 10 to 30% Silyl Terminated Polyether NJ Trade Secret Registry No.04499600-6009P, 7 to 13% Plasticizer - NJ Trade Secret Registry No. 04499600-5988P, 1 to 5% Diisodecyl Phthalate, 1 to 5% Hydrotreated Heavy Naphtha (Petroleum), 0.5 to 5% Stearic Acid, < 1% 1,2-Ethanediamine, N1-[3-(trimethoxysilyl)propyl]-, < 1% 1-Methyl-2-Pyrrolidinone, < 1% Dibutyltin bis(acetylacetonate), < 0.5% Quartz Silica |
| Application Time | 5 to 10 min |
| Paintable (Y/N) | Yes |
| Specific Gravity | 1.68 |
| Odor/Scent | Solvent |
| Color | White |
| Container Size (mL) | 310 |
| Flash Point | 144 deg F |
| Container Type | Flex-Pack |
| Form | Paste |
| Temperature Rating (deg F) | -30 to 200 |
| Curing Time | 24 hr |
- Volume
- 310 mL
- Color
- White
- Application Temp.
- 30°F - 200°F (-34°C - 93°C)
- Compatible Substrates
- Bare metal, OEM, primer
- Flash Time
- 5-10 min
- Cure Time
- 24 hr
About 3M
3M is a global leader in abrasives, masking, and body repair products. Trusted by OEM collision centers for high-performance prep and finishing solutions.
Frequently Asked Questions
What substrates can I apply 3M 08369 Seam Sealer to?
It is compatible with bare metal, OEM finishes, and primer-coated surfaces.
How long does the seam sealer take to cure?
The material cures fully in 24 hours at temperatures between 30°F and 200°F (-34°C to 93°C).
What personal protective equipment is required when using this product?
Wear chemical-resistant gloves, protective clothing, and a respirator as recommended in the SDS.
Can I sand or paint over the seam sealer?
Sanding and painting are permitted after the 24-hour cure period; the surface will be ready for topcoat once fully cured.
Documents & Safety
DANGER: This seam sealer contains hazardous chemicals that can cause serious health effects including cancer, reproductive harm, and damage to organs, eyes, and respiratory system. Required safety equipment: chemical-resistant gloves, protective clothing, and respirator. Avoid skin and eye contact, inhalation, and ingestion. Use only in well-ventilated areas. Can cause severe burns and permanent eye damage. Always refer to the full SDS before use.
Why Buy from autofxmart
- Authorized distributor — authentic, factory-fresh stock.
- Fast US shipping — most orders ship within 1 business day.
- 30-day returns — buy with confidence.
- Pro-shop pricing — bulk discounts available on request.
- Expert support — questions? Email us at support@autofxmart.com.
How to apply
Steps
1Clean both surfaces to bare, dry substrate.
2Load the cartridge and fit the mixing nozzle.
3Apply an even bead (or clamp) where needed.
4Tool or smooth the joint before it skins over.
5Allow to cure fully before stressing or painting.
Specifications
Full data
Frequently asked
Good to know
3M Products MMM is compatible with Bare Metal, Primed Surface. Always ensure the surface is properly cleaned, degreased, and sanded before application to achieve the strongest adhesion and a professional finish.
The curing time for 3M Products MMM is 24 hr. Drying and curing times may vary with temperature, humidity, and film thickness — always consult the Technical Data Sheet (TDS) for exact cycle conditions.
This listing ships 3M Products MMM in a 310 container. Check the autofxmart catalog for other sizes and bulk pricing.
Most in-stock orders for 3M Products MMM ship the same or next business day from our US warehouse. Expedited options are available at checkout. Freight-class items may require an additional 1–2 days for carrier pickup.
Yes. autofxmart is an authorized distributor of 3M Products. Every unit is factory-fresh, sealed, and backed by the manufacturer's standard warranty. If you have a concern, contact support@autofxmart.com and we will make it right.
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