Surface treatment used to be the bottleneck of production. The first car bodies, which were brush-painted with boiled linseed oil, took several weeks to dry. Back in the day, ŠKODA painters used ground-breaking nitro varnishes and spray guns, but now they work with ultramodern robotic technology. Whereas they used to mix colours by guesswork in earlier days, the current process is now fully automated, including the checking of mixture homogeneity and colour stability.
In the days of the first L&K motorcycles at the end of the 19th century, varnishes based on linseed oil or more attractive liquefied natural amber resins were used. Painters would rub pigments into binding agents on stone slabs. To completely paint a car could take between four and eight weeks, as it was necessary to coat several layers of sealant and intermediate paint with a long drying time. It was the wood-oil based materials that made it possible to paint and quickly dry in a “mere” 10 days. No wonder there was such low labour productivity and high car prices in the early days of the automobile.
This work completely changed in the 1920s. Painters began to use nitro varnishes that were suitable for rapid mass production. Nitrocellulose used during the war was applied as a binder. Synthetic thinners, pigments and softeners began to be produced on a large scale. Thorough degreasing of the undercoat also led to higher quality. Matte nitro varnishes dried for about 15 hours and even faster at higher temperatures. An intense deep shine could be achieved by using polishing paste and linen cloth. Painters no longer did polishing by hand but had electrical and pneumatic tools. Nitro varnish, capable of dissolving previously applied layers, could no longer be applied with brushes, so spray guns took over the workshops.
In late 1920s, a new binder arrived from America to Europe – alkyd resin with fatty acids called Glyptal – and form the basis of high-quality nitro-combination varnishes that were easy to apply and durable and had a deep gloss.
With the advent of drawn sheet metal facilitating the previously demanding sealing, hard alkyd resins found their use after World War II, and the time to paint a car decreased to about four hours.
In the 1960s, polyester-based paints followed, and the top layers dried at a lower temperature.
The following decade brought the body filler that protected against corrosion. The tanks that the bodies were dipped in saved the painters a lot of work, and the protective layer even got into hidden corners of the increasingly complex weldments.
In the 1990s, material losses during painting were still extraordinary and made this the most expensive stage in car production. An enormous breakthrough came with electrostatic spin coating, which applied up to 90 percent of the material in its proper place.
The painters’ working conditions have changed radically with the use of modern respirators and other protective equipment, as well as the introduction of water-soluble paints and because the most complicated tasks have been taken over by automated lines. Last year, one of the most modern paint shops started operating at the main plant of ŠKODA AUTO in Mladá Boleslav.
Even such complex technology cannot do without skilled workers. Machines have taken over the physically strenuous work, and in each stage of car painting, deft human hands will ensure that the applied material doesn’t get to places it shouldn’t be. Eagle-eyed workers who look for the slightest flaws in the paint are also invaluable and repair them at the same time – fine grinding or polishing is usually enough. These workers are assisted by the newly introduced HITECH technology by EINES, which is based on camera scans of the body surface.
... most of the L&K models were black, green, maroon, beige or red?