Bondo (putty)

Bondo putty is an automotive body filler and a brand name used by 3M for a line of American-made products for automotive, marine and household repairs.

Before the 1940s, body solder was often used to repair large imperfections prior to painting. Solder repairs were conducted using a flame and wooden paddles covered in tallow or motor oil, which prevented the half-molten lead from sticking. After the war, automotive panels became thinner and larger, with a greater susceptibility to warping. The earliest 'plastic solder' can be traced to around 1940, a do-it-yourself solution to panel beating. This gave the consumer the ability to attempt reasonably priced and long lasting repairs. These early fillers were epoxy-based and one part, drying by out gassing. The most notable early filler was called Black Magic (body filler), and was popular before Bondo's introduction. Bondo, a two-part (resin with hardener added) mix of talc and plastic, was introduced in 1955. It was developed by World War II veteran and automotive repair shop owner Robert Merton Spink of Miami, Florida.

Products sold under the Bondo brand name include automotive body fillers, all-purpose putty, and materials for repairing wood, concrete, and metal. Fiberglass mats and resins for marine vehicle repair complemented the original market in automotive maintenance. There are Bondo sealants for use on roads. In addition to its consumable products, 3M has a line of Bondo tools intended to be used with the putties and fillers.

Bondo in various forms and modified compounds is used by hobby and cosplay enthusiasts for realistically tough armor. While the resultant products are often very durable, 3M does not endorse its use as personal protection under any circumstances.

Hooverite is a castable mixture of Bondo and laminating resin used to make small models. It will not shatter, and presents a paint-ready surface, unlike most casting resins. It is informally named after Michael F. Hoover, a Los Angeles area special effects artist.

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