3M
3M 8243 SMC/Fiberglass Repair Adhesive 200 mL White/Black Cartridge Fast-Set Urethane for Backer
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Hazardous material · Liquid
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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™ SMC/Fiberglass Repair Adhesives are two-part urethanes or two-part epoxies used to bond backup strips to SMC (sheet molded compound), FRP (traditional fiberglass) and primed metal. Our adhesives provide a full range of hardness, flexibility and worktimes for jobs such as reinforcing the backside of plastic…
3M Automix 08243 is a two-part SMC/fiberglass repair adhesive supplied in a 200 mL cartridge (white/black). It is formulated for structural repairs on fiberglass, FRP, plastic, and SMC substrates where high strength and rapid return to service are required.
The system offers a work time of 50 seconds and reaches full cure in approximately 1 hour, allowing fast turnaround without sacrificing bond integrity. Excellent sprayability provides uniform coverage across up to ten coats, ensuring consistent fill and finish on complex shapes and joints.
Due to its acute toxicity, aspiration hazard, carcinogenic potential, and flammability, the adhesive must be handled with eye protection, chemical-resistant gloves, protective clothing, and a respirator in a well-ventilated area. Follow standard first-aid procedures for inhalation, skin contact, eye exposure, or ingestion as outlined in the SDS.
Why Pros Choose 3M MMA
- Two-part urethane or two-part epoxy adhesives effectively bond rigid plastic
- Commonly used to bond backup strips to SMC and FRP (traditional fiberglass)
- Frequently used for backside reinforcement repair on a variety of plastic components
- Adhesive offers excellent sag resistance
How to Use
For use to bonding small backer strips and patches to the back side of SMC and FRP repairs
- Clean and dry the substrate (fiberglass, FRP, plastic, SMC) to remove dust, oil, or loose material.
- Mix the adhesive at a 1 : 1.2 resin-to-hardener ratio; blend thoroughly before the work time expires (≈50 seconds).
- Apply the mixed adhesive using spray equipment for optimal coverage; deposit a uniform first coat.
- Allow each coat to set for the full cure time of 1 hour before applying the next coat, up to a total of 10 coats as required.
Compatibility
Compatible substrates: Fiberglass, Plastic, SMC.
Compatible paint systems: Urethane, Epoxy.
Specifications
| Part No. | 8243 |
|---|---|
| Product Line | MMA |
| MFR Model | 08243 |
| Standard/Approvals | OSHA 29 CFR 1910.1200 |
| Application | For use to bonding small backer strips and patches to the back side of SMC and FRP repairs |
| Manufacturer | 3M Products |
| Trade Mark | Automix™ |
| Alternate Part Number-1 | 60455050348 |
| UPC | 051131082434 |
| Brand | 3M™ |
| Composition | 30 to 60% Methylene Phenylene Isocyanate, 30 to 60% Urethane Prepolymer, 10 to 30% 4,4-Diisocyanatodiphenylmethane Polymer, 7 to 13% Talc, 7 to 13% Aluminum Silicate, 1 to 5% Thickening Agent |
| Application Time | 50 sec |
| Specific Gravity | 1 to 1.2 |
| Odor/Scent | Slight Isocyanate |
| Color | White/Black |
| Container Size (mL) | 200 |
| Flash Point | >383 deg F |
| Container Type | Cartridge |
| Form | Liquid |
| Temperature Rating (deg F) | -20 to 180 |
| Curing Time | 1 to 4 hr/15 to 30 Min/24 hr/30 to 60 Min/5 to 10 Min |
- Cure Time
- 1 hour
- Work Time
- 50 sec
- Coverage
- excellent sprayability
- Compatible Substrates
- fiberglass, FRP, plastic, SMC
- Number of Coats
- 10
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 this adhesive to?
The adhesive is compatible with fiberglass, FRP (fiberglass reinforced plastic), plastic, and SMC (sheet-molded composite).
How long does it take for the adhesive to cure?
Full cure is achieved in approximately 1 hour at the recommended application temperature.
What personal protective equipment (PPE) is required when using this product?
Use eye protection, chemical-resistant gloves, protective clothing, and a respirator as indicated on the safety data sheet.
How much working time do I have after dispensing?
The work (pot) time is about 50 seconds before the adhesive begins to set.
Documents & Safety
DANGER: This adhesive contains hazardous chemicals that can cause serious health effects including cancer, reproductive harm, and organ damage. May be flammable and harmful if inhaled or absorbed through skin. Required PPE: safety glasses or goggles, chemical-resistant gloves, protective clothing, and respiratory protection in poorly ventilated areas. Avoid skin and eye contact. Use only with adequate ventilation. 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.
Specifications
Full data
Frequently asked
Good to know
3M Products MMA is compatible with Fiberglass, Plastic, SMC. 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 MMA is 1 to 4 hr/15 to 30 Min/24 hr/30 to 60 Min/5 to 10 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 MMA in a 200 container. Check the autofxmart catalog for other sizes and bulk pricing.
Most in-stock orders for 3M Products MMA 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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