Weld-On 4784 is a clear, thin to medium bodied solvent cement. It cures rapidly with the dissipation of the solvent at room temperature resulting in a very strong, but flexible bond. The bond for Weld-On 4784 forms very quickly, so that some parts may be handled within a few minutes of application. Bond strength continues to develop very rapidly, reaching a substantial level within hours. Joints are water and weather resistant and will generally have similar physical and chemical properties to acrylic plastic. A long service life under normal conditions is provided by Weld-On 4784, however under some harsh conditions such as high heat or extended sun exposure, some yellowing of the bond line may occur.
Weld-On 4784 is a flexible vinyl cement formulated to bond flexible vinyl to itself or a variety of other thermoplastics such as cellulose acetate butyrate, rigid PVC, acrylic, Kydex® and porous materials such as fabrics.
Weld-On 4784 is recommended for joining flexible vinyl to itself. It can be used to repair or patch vinyl furniture seats and also bond other thermoplastics to various materials (e.g. plastic to materials such as cotton, etc.) Although weather and water resistant, constant immersion in water could weaken the bond joint. For prolonged contact with water, Weld-On 66 is recommended.
This product must be shipped via a ground service.
Adhesive Properties and Characteristics @ 73°F (23°C)
|335 ± 150 cps|
Fixture Time (Time to reach 80% of ultimate strength)
Time to reach Ultimate Bond Strength
Specific Gravity (g/cc)
|0.904 ± 0.01|
Directions for Use
Clean surfaces to be joined.
Coat each mating surface. May be applied with brush, syringe, gun, dauber, etc.
Press parts together immediately and hold a few seconds until “grab” begins. For quicker initial set, coat each surface, wait 10 to 20 seconds, then press parts firmly together.
Good strength will develop in a few minutes with some materials. Bond strength will be considerable in a few hours and will reach high strength in 24 to 48 hours. Therefore, strength will continue to increase gradually for some weeks.
Three years in tightly sealed containers. The date code of manufacture is stamped on the bottom of the container. Stability of the product is limited by the evaporation of the solvent when the container is opened. Evaporation of solvent will cause the cement to thicken and reduce its effectiveness. Adding of thinners to change viscosity is not recommended and may significantly change the properties of the cement.
Safety and Environmental Precautions
This product is a flammable, fast evaporating solvent cement. It is considered a hazardous material. In conformance with the Federal Hazardous Substance Labeling Act, the following hazards and precautions are given. Purchasers who may re-package this product must also conform to all local, state, and federal labeling, safety and other regulations. VOC emissions do not exceed 510 grams per liter.
DANGER: EXTREMELY FLAMMABLE. VAPOR HARMFUL. MAY BE HARMFUL IF SWALLOWED. MAY IRRITATE SKIN OR EYES
Keep out of reach of children. Do not take internally. Keep away from heat, spark, open flame and other sources of ignition. Keep container closed when not in use. Store away from direct sunlight between 40º F – 110º F (5º C – 43º C). Use only with adequate ventilation. Avoid breathing of vapors. Atmospheric levels should be maintained below established exposure limit values contained in Section II and VIII of the Material Safety Data Sheet. If airborne concentrations exceed those limits, use of a NIOSH-approved organic vapor cartridge respirator with full face-piece is recommended. The effectiveness of an air-purifying respirator is limited. Use it only for a single short-term exposure. For emergency and other conditions where short-term exposure guidelines may be exceeded, use an approved positive pressure self-contained breathing apparatus. Do not smoke, eat or drink while working with this product. Avoid contact with skin, eyes and clothing. May cause eye injury. Protective equipment such as gloves, safety goggles and impervious apron should be used. Carefully read Material Safety Data Sheet and follow all precautions.
Contains Tetrahydrofuran (109-99-9). Do not use this product for other than intended use.
“Title III Section 313 Supplier Notification”: This product contains toxic chemicals subject to the reporting requirements of Section 313 of the Emergency Planning and Community Right-to-Know Act of 1986 and of 40CFR372. This information must be included in all Material Safety Data Sheets that are copied and distributed for this material.
Inhalation: If overcome with vapors, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Call physician.
Eye Contact: Flush with plenty of water for 15 minutes and call a physician.
Skin Contact: Wash skin with plenty of soap and water for at least 15 minutes. If irritation develops, get medical attention.
Ingestion: If swallowed, give 1 or 2 glasses of water or milk. Do not induce vomiting. Contact physician or poison control center immediately.