3M
3M 8365 Beige 1‑Component Seam Sealer 310 mL Cartridge – 24 hr Cure, Paintable After 30 min
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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
California Pro65 Warning: Cancer and Reproductive Harm
Tap for details → P65Warnings.ca.gov
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Overview
Built for the job.
Our 3M™ urethane seam sealer is a high solids seam sealer ideal for sealing automotive and RV seams and joints. It adheres well to bare metal, primed metal and painted surfaces and if desired can be smoothed to a featheredge and/or brushed. Tack-free and paintable after 30 to 45 min, this urethane formula is…
3M 08365 is a single-component, paste-type seam sealer supplied in a 310 mL cartridge. It is formulated for sealing panel seams and joints prior to filler application, providing a flexible barrier that prevents moisture ingress and improves adhesion of subsequent coatings.
The sealer cures to full strength within 24 hours at ambient temperatures ranging from 25 °F to 180 °F, allowing rapid shop turnaround. Its low VOC content of 9.8 lb/gal meets most environmental regulations while delivering consistent coverage on aluminum, bare metal, and primed substrates. The paste consistency ensures easy extrusion and uniform bead placement across complex seam profiles.
Due to its classification as an acute toxicant, carcinogen, and skin corrosive, appropriate personal protective equipment-gloves, protective clothing, and a respirator-is required during handling. Use in well-ventilated areas and follow the SDS first-aid procedures for inhalation, skin contact, eye exposure, or ingestion.
Why Pros Choose 3M 1-Component
- High quality, single-component formula adheres well to bare metal, primed metal and painted surfaces
- Moisture curing property provides excellent performance in high heat and humidity environments
- Non-shrinking, non-cracking, low/no odor formula remains flexible and offers superior results to solvent-based sealers
- Paintable after 30 to 45 min
- Thick consistency is able to fill large voids
- Can be smoothed to a featheredge or brushed
- Recommended for use with 3M™ single-component cartridge applicator gun PN08990 or 3M™ professional caulking gun PN08993
How to Use
For sealing of seams to prevent intrusion of water, dust, air, fumes, may be used for interior or exterior seams of primer coated substrates
- Clean the substrate (aluminum, bare metal, or primer) to remove oil, grease, and loose material; dry thoroughly.
- Verify ambient temperature is between 25 °F and 180 °F before application.
- Apply a uniform bead of the 1-component seam sealer directly from the cartridge; shape as needed with a spreader or putty knife.
- If additional thickness is required, apply a second coat after the first has reached initial set (typically within a few minutes).
- Allow the sealant to cure for 24 hours before sanding, priming, or applying topcoat.
Compatibility
Compatible substrates: Bare Metal.
Compatible paint systems: Urethane, Epoxy, Solvent.
Specifications
| Part No. | 8365 |
|---|---|
| Product Line | MMM |
| MFR Model | 08365 |
| Standard/Approvals | California Pro65 Warning: Cancer and Reproductive Harm |
| Application | For sealing of seams to prevent intrusion of water, dust, air, fumes, may be used for interior or exterior seams of primer coated substrates |
| Manufacturer | 3M Products |
| Alternate Part Number-1 | 60455054613 |
| UPC | 051135083659 |
| Brand | 3M™ |
| Maximum Sale Quantity | 12 |
| Maximum Sale Day | 7 |
| Applicable Materials | Bare Metal, Painted Surfaces, Primed Metal |
| Composition | 15 to 40% Urethane Polymer, 10 to 30% PVC Polymer, 10 to 30% Sulfonic Acids, C10-18-Alkane, pH Esters, 5 to 10% Xylene, 1 to 5% Calcium Oxide, 1 to 5% Ethylbenzene, 1 to 5% Hydrotreated Light Petroleum Distillates, 1 to 5% Titanium Dioxide, 0.1 to 1 P,P'-Methylenebis(Phenyl Isocyanate) |
| Application Time | 10 to 20 min |
| Paintable (Y/N) | Yes |
| Specific Gravity | 1.17 |
| Sprayable (Y/N) | Yes |
| Base Type | Moisture-Curing Urethane |
| Component | 1K |
| Color | Beige |
| Container Size (mL) | 310 |
| Flash Point | 92 deg F |
| Container Type | Cartridge |
| Form | Paste |
| Temperature Rating (deg F) | -25 to 180 |
| Type | 1-Component |
| Curing Time | 24 hr |
- VOC
- 9.8 lb/gal
- Application Temp.
- 25-180 °F
- Compatible Substrates
- Aluminum, bare metal, primer
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 are compatible with this seam sealer?
The product is approved for use on aluminum, bare metal, and primer-coated surfaces.
How long does the seam sealer take to cure?
Full cure is achieved in approximately 24 hours at temperatures within the recommended range.
What personal protective equipment (PPE) is required when applying this product?
Use chemical-resistant gloves, protective clothing, and a respirator as specified in the safety data sheet.
At what temperature can I apply the seam sealer?
The recommended application temperature is between 25 °F and 180 °F.
Documents & Safety
DANGER: This seam sealer contains chemicals that may cause cancer, reproductive harm, and organ damage. Can cause serious eye damage and skin irritation. Required PPE: chemical-resistant gloves, protective clothing, and respiratory protection when spraying or in poorly ventilated areas. Avoid skin and eye contact. Use only with adequate ventilation. Do not ingest. Always refer to the full SDS before use.
Why Buy from autofxmart
- Authorized distributor — authentic, factory-fresh stock.
- Fast US shipping — orders ship within 2 business days, lower 48 only.
- 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. 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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