Windshield wash is always in demand, since no vehicle can do without it. Obviously, the better the sales, the more profit for the manufacture. Demand leads to increased prices. The higher the price, the more lucrative the production. Production, however, requires knowledge of the composition.
This information is not secret. Manufacturer are legally required to indicate the composition of their product on the label.
The base component of the windshield washer is alcohol. It assures stability to cold temperature. Most often, washer liquids are based on ethyl, isopropyl or methyl alcohol. The selection is limited by law and the influence of the alhocol on the human body (some substances may be banned for use).
Water is another component. Since the finished product must not contain contaminants or sediment, water should be sufficiently clean. Besides, if the water contains a lot of iron and mineral salts, the performance of the washing fluid suffers. Cloudy solution and sediment are harmful to the spraying nozzles.
Surfactants remove dirt from the glass surface, including wax, soot, dirt and exhaust sediment.
Ethylene glycol is required to keep the liquid flowing, actually preventing freezing of the washing liquid.
For color, dyes are mixed into the liquid. If the color is too dark, it might be because the liquid is low quality and the producer wants to hide cloudiness or sediment.
Odorants are used two attenuate the alcohol odor. Those are non-allergenic and safe. Most drivers and passengers prefer flower and herbal scents.