What is the formula for automotive putty?

[MaciMarie]

Automotive putty formula consists of double fly powder, gypsum powder, carboxymethyl cellulose powder, retarder, and thickener. Below is a detailed introduction to the use of automotive putty: 1. Mix evenly: Before using the putty, it must be mixed evenly according to the formula. The mixing amount should not be too large, otherwise, it will increase the mixing time and cause the putty to harden prematurely. 2. Applying putty: There are different methods for applying putty, including full scraping and alternating soft and hard scraping. Full scraping is further divided into filling scraping and close scraping, while alternating soft and hard scraping includes "apply first then scrape" and "apply while scraping." The purpose of filling scraping is to use thicker putty to fill the surface depressions of the component in several passes.

[IsabelleMarie]

I've worked with automotive body filler for many years. The basic formula consists of polyester resin as the base material, mixed with fillers like talc or calcium carbonate to increase hardness and volume, plus catalysts such as peroxides for rapid curing. Typical proportions are about 60% resin, 30% filler, with small amounts of additives like anti-shrink agents. When mixing, it's crucial to thoroughly blend the resin and catalyst in the specified ratio – any carelessness can cause bubbling or premature hardening that makes application difficult. During my time at the auto shop, I always emphasized surface preparation: first sanding off rust, applying thin filler layers, then carefully sanding smooth after curing. Since filler's purpose is to level imperfections before painting, using the wrong formula can compromise finish quality or require rework. That's why I recommend starting with reputable brand-name products rather than cutting corners with cheap alternatives.

[SanRobert]

DIY car body filler is quite fun! The recipe is basically three things: resin (like that polyester-based gel substance), filler (I usually use talcum powder or calcium carbonate to thicken it), and catalyst (small tube of hardener). The ratio is roughly more resin, less filler, and just a small portion of catalyst. When mixing, you need to stir quickly and evenly, with the curing time controlled at 5-10 minutes—too slow and the work drags, too fast and it's hard to handle. I’ve also found that safety is crucial for home projects like this—wear gloves and work in a ventilated area to avoid skin contact and allergies. Cost-wise, mixing your own formula can save money, much cheaper than buying pre-made filler, but for first-timers, I recommend testing small batches to ensure a smooth surface after filling, making it easier to paint and enhancing the car’s appearance.

[McBarrett]

In the old days, car body filler formulas were quite simple, typically using polyester resin as the base, mixed with gypsum or plaster as filler, and a small amount of catalyst to speed up hardening. The rough ratio was about half resin, a bit more filler, and just a trace of catalyst. Mixing was done manually to avoid bubble formation. In my youth, I used it to repair dents in car bodies with decent results, though the curing was slow. Looking back now compared to modern chemical products, it was less environmentally friendly. The basic principles of the formula haven't changed much—the core focus remains on easy sanding and strong adhesion to ensure smooth and durable paint application.