3M
3M Ultrapro 8361 1-Part Seam Sealer, Gray, 10.5 oz Flex-Pack
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Hazardous material · Paste
This hazardous material ships ground-only. A handling surcharge may be added at checkout.
Shipping restrictions apply
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 Ultrapro 08361 is a single-component, paste-type seam sealer designed for automotive body repair. It provides an economical solution for sealing seams on bare metal or primed surfaces before panel bonding or painting.
The formulation cures to handling strength in approximately 30 minutes at temperatures between 20°F and 180°F (-28°C to 82°C), allowing rapid progression through the repair cycle. Its gray pigment blends with typical automotive primers, and the paste consistency ensures uniform coverage on complex seam geometries.
Due to its acute toxicity, aspiration hazard, and classification as a carcinogen and skin corrosive, use requires a respirator and adequate ventilation. Follow standard PPE protocols and consult the SDS for detailed first-aid procedures.
Why Pros Choose 3M 1-Part, Economical
- 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 general-purpose automotive seams, including door skins, rocker panels, rear body panels, trunk seams, floor pans and more
- Clean the substrate (bare metal or primed surface) of dust, oil, and loose material; ensure it is dry.
- Verify ambient temperature is between 20 °F and 180 °F (-28 °C to 82 °C). The product can be applied at any temperature within this range.
- Apply the paste directly from the Flex-Pack using a brush, roller, or spatula. Apply a continuous, uniform bead to fill seams.
- If additional coverage is required, allow the first coat to cure for 30 minutes before applying a second coat.
- After final coat, allow the seam sealer to fully cure (minimum 30 minutes) before proceeding with subsequent body work.
Compatibility
Compatible substrates: Bare Metal.
Compatible paint systems: Urethane, Epoxy, Solvent.
Specifications
| Part No. | 8361 |
|---|---|
| Product Line | MMM |
| MFR Model | 8361 |
| Standard/Approvals | California Pro65 Warning: Cancer and Reproductive Harm |
| Application | For general-purpose automotive seams, including door skins, rocker panels, rear body panels, trunk seams, floor pans and more |
| Manufacturer | 3M Products |
| Trade Mark | Ultrapro™ |
| Alternate Part Number-1 | 60980034726 |
| UPC | 051131168312 |
| Brand | 3M™ |
| Maximum Sale Quantity | 6 |
| Maximum Sale Day | 7 |
| Applicable Materials | Metal |
| Composition | 15 to 40% Urethane Polymer, 10 to 30% PVC, 10 to 30% Sulfonic Acids, C10-18-Alkane, pH Esters, 3 to 7% Xylene, Titanium Dioxide, 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 | 5 to 10 min |
| Paintable (Y/N) | Yes |
| Specific Gravity | 1.17 |
| Base Type | Urethane |
| Component | 1K |
| Odor/Scent | Solvent |
| Color | Gray |
| Container Size (mL) | 310 |
| Flash Point | 92 deg F |
| Container Size (oz) | 10.5 |
| Container Type | Flex-Pack |
| Form | Paste |
| Temperature Rating (deg F) | >200 deg C Autoignition, -30 to 200 |
| Type | 1-Part, Economical |
| Curing Time | 30 min |
- Application Temp.
- 20°F - 180°F (-28°C - 82°C)
- Compatible Substrates
- 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 can I apply the 3M Ultrapro 08361 Seam Sealer to?
The sealer is formulated for use on bare metal and primer-coated surfaces.
How long does it take for the seam sealer to cure?
Curing time is approximately 30 minutes under normal conditions.
What personal protective equipment is required when applying this product?
A respirator must be worn due to acute toxicity and respiratory hazards. Standard safety glasses, gloves, and protective clothing are also recommended.
Documents & Safety
DANGER: This seam sealer contains hazardous chemicals that can cause serious health effects including cancer, reproductive harm, and organ damage. May cause severe eye and skin irritation. Required PPE: chemical-resistant gloves, protective clothing, and respirator. Use only in well-ventilated areas. Avoid skin and eye contact. Do not ingest. Can be harmful if inhaled. 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 30 min. 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 10.5 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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